JP6119630B2 - Resin determination method and sorting apparatus - Google Patents

Description

  The present invention relates to a resin determination method and a resin sorting apparatus using the method, and more particularly to a method for determining a resin material by X-ray and a resin sorting apparatus using the method.

  The transmission intensity of X-rays that have been irradiated to an object and transmitted through the object is determined based on the material and density of the object, and the thickness. For this reason, if only the X-ray transmission intensity is referred to in order to specify the material of the object, it may cause a large determination error due to the thickness of the object.

  Conventionally, as a method for determining a material using an X-ray transmission intensity considering the thickness, there is a method called an energy subtraction method using an X-ray dual sensor or the like. In this method, the transmission X-ray intensity on the low energy side and the transmission X-ray intensity on the high energy side are measured, and the difference between them is calculated, thereby reducing the influence of the thickness. In this energy subtraction method, the transmission X-ray intensity on the low energy side and the transmission X-ray intensity on the high energy side are logarithmically transformed to generate an equivalent thickness image, weighted using parameters, and the difference value between the two using a difference equation To reduce the effect of thickness.

  However, with this method, the difference value changes greatly depending on the parameter setting, and the influence of thickness may not be reduced. Therefore, a separation matrix using independent component analysis is calculated, and weight parameters are automatically calculated. Thus, a technique has been proposed that makes it possible to obtain an optimum difference equation and reduce the influence of thickness (for example, see Patent Document 1).

JP 2010-91483 A

  However, when the material discrimination method using the X-ray transmission intensity according to Patent Document 1 is applied to the resin material discrimination, there are the following problems.

  When determining the material of the resin, the difference equation defined by the energy subtraction method can determine the resin piece not containing the additive and the resin piece containing the additive without being affected by the thickness. . However, there are two types of resin materials that can be determined. Therefore, there is a problem that three or more determinations including determination of the type of additive cannot be performed.

  The present invention has been made to solve the above-described problems, and uses a resin determination method for determining the resin material for each type of additive contained in the plastic resin fragment, and the method. It is to provide a resin sorting device.

The resin determination method according to the present invention is a resin piece group composed of a plurality of resin pieces having a predetermined thickness, the resin piece group containing no additive, and the first resin containing the first additive. In the second resin piece group containing the one group and the second additive, each resin piece constituting each resin piece group is irradiated with X-rays, and the transmitted X-ray intensity and high energy on the low energy side are transmitted. The difference value, which is the difference from the X-ray intensity on the energy side, and the relationship between the difference value and the transmitted X-ray intensity on the low energy side are recorded in advance, and an arbitrary resin piece is irradiated with X-rays and transmitted. The difference value that is the difference between the X-ray intensity on the low energy side and the X-ray intensity on the high energy side, and the relationship between the difference value and the transmitted X-ray intensity on the low energy side are obtained, and the previously recorded difference value And comparison with the relationship between the difference value and the transmitted X-ray intensity on the low energy side In Rukoto, there is provided a method for determining the content and type of additives the arbitrary resin pieces, the attenuation coefficients of the low energy side of the resin piece containing no additive MyuNL, the resin piece containing no additive high The energy-side attenuation coefficient is μNH, and the ratio of the low-energy-side attenuation coefficient of the resin piece not containing the additive to the high-energy-side attenuation coefficient of the resin piece not containing the additive is k = μNL / μNH, the transmitted low When the X-ray intensity on the energy side is IL, the X-ray intensity on the irradiated low energy side is IL0, the transmitted X-ray intensity on the high energy side is IH, and the X-ray intensity on the irradiated high energy side is IH0, The difference value is a method of ln (IL / IL0) −k · ln (IH / IH0).

  According to the determination method of the resin according to the present invention, the resin piece for each type of additive can be determined by comparing the relationship between the transmission X-ray intensity on the low energy side and the difference value with existing information, By adjusting the threshold value of the resin piece containing no additive and the resin piece containing the additive based on the distribution information related to the resin piece for each type of additive, the effect of accurately determining the resin material can be achieved. Play.

It is a graph which shows the relationship between the difference value and thickness for demonstrating the determination method which concerns on Embodiment 1 of this invention. It is a graph which shows the relationship between the transmission X-ray intensity on the low energy side, and thickness for demonstrating the determination method which concerns on Embodiment 1 of this invention. It is a figure which shows the flowchart of the determination method which concerns on Embodiment 1 of this invention. It is a figure which shows the flowchart of the determination method of the resin piece of the resin of a comparative example. It is a graph which shows the relationship between the difference value and thickness for demonstrating the determination method which concerns on Embodiment 2 of this invention. It is a figure which shows the flowchart of the determination method which concerns on Embodiment 2 of this invention. It is a figure which shows typically the selection apparatus which concerns on Embodiment 3 of this invention. It is a figure which shows typically the selection apparatus which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  First, the outline | summary of the determination method of resin which concerns on this invention is demonstrated. The resin determination method according to the present invention generally includes the following steps. Hereinafter, the resin piece includes, of course, a novel resin molded product, but the present invention is an invention made from the viewpoint of plastic recycling, and is mainly a crushing resin piece (hereinafter referred to as a used plastic resin). In some cases, this may be described simply as a resin piece).

  A resin piece group consisting of a plurality of resin pieces having different known thicknesses, a resin piece group not containing an additive, a first resin piece group containing a first additive, and a second addition Difference between the X-ray intensity on the low energy side and the X-ray intensity on the high energy side that are transmitted through the X-rays irradiated to each resin piece constituting each resin piece group in the second resin piece group containing the agent Calculating a difference value (hereinafter, may be described only as a difference value) for each resin piece.

  Resin having a different thickness constituting each of a resin piece group containing no additive, a first resin piece group containing a first additive, and a second resin piece group containing a second additive A step of storing a difference value obtained by calculation in advance for a piece.

    Resin having a different thickness constituting each of a resin piece group containing no additive, a first resin piece group containing a first additive, and a second resin piece group containing a second additive The step of storing in advance the relationship between the difference value and the transmitted X-ray intensity on the low energy side for the piece.

  Distribution of difference values of resin pieces having different thicknesses constituting a resin piece group not containing an additive and thicknesses constituting a resin piece group (first resin piece group and second resin piece group) containing an additive A step of setting and storing a threshold value in advance between the difference value distributions of resin pieces of different sizes.

  The difference that is the difference between the X-ray intensity on the low energy side and the X-ray intensity on the high energy side, which is irradiated with X-rays to the arbitrary resin piece whose additive content and thickness are unknown Calculating the value for any piece of resin.

  The difference value calculated for an arbitrary resin piece is compared with a threshold value stored in advance, and whether the arbitrary resin piece to be judged is a resin piece that does not contain an additive or a resin piece that contains an additive Determining.

  When it is determined by the above steps that the arbitrary resin piece is a resin piece containing an additive, the relationship between the difference value calculated for the arbitrary resin piece and the transmitted X-ray intensity on the low energy side is obtained. , A thickness constituting each of the resin piece group not containing the pre-stored additive, the first resin piece group containing the first additive, and the second resin piece group containing the second additive A step of determining a resin piece for each type of additive by comparing a difference value between resin pieces of different thicknesses and a relationship between transmitted X-ray intensity on the low energy side.

  In addition, the resin piece group (the 1st resin piece group and the 2nd resin piece group) containing the distribution of the difference value of the several resin piece from which thickness which comprises the resin piece group which does not contain an additive, and an additive The type and thickness of resin pieces that have already been selected for any resin piece to be judged when a threshold value is set in advance between the difference value distributions of a plurality of resin pieces having different thicknesses constituting From this distribution, the characteristics of the resin pieces to be sorted are captured, and the preset threshold value is optimized using the data, thereby further improving the sorting accuracy.

Hereinafter, the resin determination method according to the first embodiment of the present invention will be described. The intensity of X-rays transmitted through an object after irradiating the object with X-rays (transmitted X-ray intensity) is determined based on characteristics such as an attenuation coefficient due to the material of the object and the thickness of the object. When the transmitted X-ray intensity is I, the irradiated X-ray intensity is I ₀ , the attenuation coefficient is μ, and the thickness is x, the following equation 1 is established.

  As shown in Equation 1, only the transmitted X-ray intensity is affected by the thickness of the object. The pieces of used plastic resin to be recycled had variations in thickness, and when the material was specified, a determination error due to the thickness occurred.

  On the other hand, in the method of measuring transmitted X-ray intensity, an object is irradiated with two types of X-rays having different energy distributions, and the X-ray intensity transmitted through the object is sequentially detected by one type of detector, or 1 By irradiating the object with various types of X-rays and detecting the X-ray intensity transmitted through the object simultaneously with two types of detectors with different X-ray energy distributions that can be detected, there are two types: the low energy side and the high energy side There is a dual energy method for measuring the transmitted X-ray intensity. By using a technique called a difference method for the two types of transmitted X-ray intensities on the low energy side and the high energy side, it is possible to eliminate the influence of the thickness as much as possible and determine the material of the object.

  Next, the calculation method of the difference method will be described. The transmitted X-ray intensities on the low energy side and the high energy side of the object are expressed by the following formulas 2 and 3, respectively.

このとき、Ｉ_Ｌは低エネルギー側の透過Ｘ線強度、Ｉ_Ｌ０は低エネルギー側の照射Ｘ線強度、μ_Ｌは低エネルギー側の減弱係数、Ｉ_Ｈは高エネルギー側の透過Ｘ線強度、Ｉ_Ｈ０は高エネルギー側の照射Ｘ線強度、μ_Ｈは高エネルギー側の減弱係数、ｘは厚さである。

At this time, I _L is the transmission X-ray intensity on the low energy side, I _L0 is the irradiation X-ray intensity on the low energy side, μ _L is the attenuation coefficient on the low energy side, I _H is the transmission X-ray intensity on the high energy side, I _H0 is irradiated X-ray intensity of the high energy side, mu _H is attenuation coefficient of the high-energy side, x is the thickness.

  Further, the difference value S between the transmitted X-ray intensities on the low energy side and the high energy side of the object is represented by the following mathematical formula 4.

If the value of k such that (k · μ _H −μ _L ) = 0, that is, the ratio μ _L / μ _H of the attenuation coefficient between the low energy side and the high energy side of the object is set to k, the difference value S of the object Becomes 0 regardless of the thickness.

  Next, the difference method will be described using a specific example. For example, the case where the resin piece which does not contain an additive and the resin piece containing an additive are determined is assumed.

The transmission X-ray intensities on the low energy side and the high energy side of the resin pieces not containing an additive having an attenuation coefficient on the low energy side of μ _NL and an attenuation coefficient on the high energy side of μ _NL are in accordance with Equations 2 and 3. The following formulas 5 and 6 are obtained, respectively.

When the value of k in Equation 4 is set to the ratio μ _NL / μ _NH of the attenuation coefficient between the low energy side and the high energy side of the resin piece containing no additive, (k · μ _H −μ _L ) = 0. Therefore, the difference value S of the resin piece not containing the additive is 0 regardless of the thickness.

On the other hand, in the attenuation coefficients of the low-energy side mu _AL, transmitted X-ray intensity of the low energy side and the high-energy side of the resin piece attenuation coefficient of high energy side contains an additive which is mu _AH is Equations 2 and According to 3, Equations 7 and 8 below are obtained.

Since the attenuation coefficient of the resin piece containing the additive and the resin piece not containing the additive are different, when the value of k in Equation 4 is set as k = μ _NL / μ _NH , (k · μ _H −μ _L ) ≠ 0, and the difference value S of the resin pieces containing the additive has a linear relationship depending on the thickness x.

  In this way, the difference value S can be used to determine a resin piece that does not contain an additive and a resin piece that contains an additive.

  Furthermore, for example, in the crushed mixed resin piece to be sorted, the resin piece not containing the additive, the resin piece containing the additive A1, and the additive A1 have different attenuation coefficients on the low energy side and the high energy side. When resin pieces containing the additive A2 are mixed, the following method can be used to determine these three types.

When the difference value S1 of the resin piece containing the additive A1 and the difference value S2 of the resin piece containing the additive A2 are compared, k = so that the difference value S of the resin piece containing no additive is 0. When Equation 4 set as μ _NL / μ _NH is used, the difference value S is distributed on a straight line having a slope depending on the thickness x of the resin piece, and therefore the combination of the thickness x and the type of additive contained Depending on the case, the resin piece containing the additive A1 and the resin piece containing the additive A2 may have the same difference value S, that is, S1 = S2.

In this case, the transmission X-ray intensity on the low energy side represented by Formula 1 of the resin piece that gives the difference value S1 of the resin piece containing the additive A1 and the same difference value S2 of the resin piece containing the additive A2 since I _L are different, and the resin strips containing additive A1 by comparing the transmitted X-ray intensity I _L, contain additives A2 can determine whether it is a resin piece, as a result, the additive Three types of resin pieces that are not contained, a resin piece that contains the additive A1, and a resin piece that contains the additive A2 can be selected.

  The additive here has a property of absorbing X-rays, and is an element (carbon (C), hydrogen (H), nitrogen (N), oxygen (mainly constituting the resin piece to be selected) O)) An additive having an element other than. Specifically, an inorganic additive, an additive having a metal element (Na to U) (metal additive), an additive having a halogen element (Cl, Br) (halogen additive), phosphorus (P ) Containing additives (phosphorous additives) and sulfur (S) containing additives (sulfur additives).

  Next, as an outline of the method for determining the material of the resin piece, the resin piece group that does not contain the above-described additive, the first resin piece group that contains the first additive, and the second additive The resin pieces constituting each of the second resin piece groups to be processed are resin pieces containing 10 wt% glass filler as the first additive, and bromine-based flame retardant (bromine concentration 1 wt% as the second additive). The outline of a technique for determining and recovering resin pieces that do not contain an additive from a crushed mixed resin piece group in which these resin pieces are mixed will be described.

  A group of resin pieces not containing an additive consisting of a plurality of resin pieces having different known thicknesses, a first group of resin pieces containing a first additive, and a second group containing a second additive FIG. 1 shows graphs A, B, and C showing the relationship between the thickness and the corresponding difference value for the resin pieces constituting each of the resin piece groups. Graph A is a resin piece constituting a resin piece group not containing an additive (here, resin piece P0), and graph B is a resin constituting a resin piece group containing 10 wt% glass fiber as an additive. A piece (here, referred to as a resin piece P1) and a graph C show the evaluation results of a resin piece (here referred to as a resin piece P2) containing 1 wt% bromine (Br) as an additive.

As shown in the graph A, the relationship between the thickness x of the resin P0 and the difference value S is the attenuation of the low energy side and the high energy side of the resin piece P0 in the equation of the difference value S expressed by Equation 4. When the ratio of the coefficients is set, (k · μ _H −μ _L ) = 0, so that the difference value S 0 of the resin piece not containing the additive becomes 0 regardless of the thickness. On the other hand, the resin piece P1 and the resin piece P2 have a difference value S of (k · μ _H −μ _L ) ≠ 0 in the expression of the difference value S expressed by Equation 4, and the difference value S is increased as the thickness x of the resin piece increases. It becomes small and it turns out that there is thickness dependence. In addition, the slope of the graph changes depending on the type of additive in the resin piece P1 and the resin piece P2.

  When determining the resin piece P0, the resin piece P1, and the resin piece P2, the threshold value J1 of the difference value S is set between S0 = 0 and, for example, the difference value S1 of the thickness 1 mm of the resin piece P1. Can be determined. That is, when the difference value S is larger than the threshold value J1, it is determined as the resin piece P0, and when it is smaller than the threshold value J1, it is determined as the resin piece P1 or the resin piece P2. Therefore, it is possible to determine whether the resin piece P0 is different from the resin piece P1 and the resin piece P2.

  However, it is impossible to determine whether the difference value S is the resin piece P1 or the resin piece P2 only by providing the threshold value J1. Therefore, it is not possible to determine three types of resin pieces P0, resin pieces P1, and resin pieces P2. For example, since the difference value S1 (Si1) of the resin piece P1 having a thickness of 4 mm and the difference value S2 (Br1) of the resin piece P2 having a thickness of 2 mm show the same value, it is determined only by providing the threshold value J1 in the difference value S. Can not do it.

  On the other hand, FIG. 2 shows graphs D to F showing the relationship between the thickness of the resin having a predetermined thickness that is known and the transmitted X-ray intensity on the low energy side expressed by the mathematical formula 2 corresponding thereto. Graph D is a resin piece P0 containing no additive, Graph E is a resin piece P1 containing 10 wt% glass fiber as an additive, and Graph F is a resin piece containing 1 wt% bromine (Br) as an additive. The result evaluated about P2 is shown.

Since the transmission X-ray intensity I _L 1 (Si2) on the low energy side of the resin piece P1 with a thickness of 4 mm and the transmission X-ray intensity I _L 2 (Br2) on the low energy side of the resin P2 with a thickness of 2 mm are different, this relationship It is possible to determine whether the resin piece to be measured is the resin piece P1 or the resin piece P2.

That is, by using both of the relationship between the difference values S and the low energy side of the transmitted X-ray intensity I _L, irrespective of the thickness, resin specimen resin piece P0 measured, resin pieces P1, or resin pieces P2 Can be determined. For example, as shown in Table 1, a plurality of resin pieces P0 having different known thickness, resin pieces P1, and a combination of the transmitted X-ray intensity of the low-energy side of the resin piece P2 I _L and the difference value S It is obtained in advance and stored in a storage device such as a memory. For any resin piece that is the measurement target, the transmission X-ray intensity _IL and the difference value S on the low energy side are obtained and compared with the values shown in the following Table 1 stored in advance. It can be determined whether a certain resin piece is the resin piece P0, the resin piece P1, or the resin piece P2.

  FIG. 3 is a flowchart showing an example of a technique for determining whether or not a resin piece contains an additive and collecting each resin piece. A more specific description will be given based on the flowchart and Table 1.

  In FIG. 3, the first step F1 is a step of setting a threshold value between the difference value of the resin piece not containing the additive and the difference value of the resin piece containing the additive. For example, in the example shown above, the resin piece P0 containing no additive, the resin piece P1 containing 10 wt% glass fiber as the additive, and the resin containing 1 wt% bromine (Br) as the additive In the case of the resin piece group composed of the pieces P2, as shown in Table 1, the difference value S0 = 0 of the resin piece P0 and the difference value S1 of thickness 1 mm which is the maximum value of the difference value S of the resin piece P1 = −0. Threshold value J1 = −0.003 is set between 005 and 005. At this time, the k value of the difference value S expressed by Equation 4 uses the ratio of the attenuation coefficient between the low energy side and the high energy side of the resin piece P0 not containing the additive.

The next step F2 is a resin piece group consisting of a plurality of resin pieces having different known thicknesses, and the difference measured for each of the resin piece group consisting of the resin piece P0, the resin piece P1, and the resin piece P2. a step of storing the relationship between the transmitted X-ray intensity I _L of the value S and the low energy side. For example, here, the contents shown in Table 1 are stored.

  In the next step F3, an arbitrary resin piece to be measured is irradiated with X-rays, the transmission intensity of the X-rays transmitted through the resin piece is measured, and the difference value S is calculated.

  The next step F4 is a step of comparing the difference value S of an arbitrary resin piece to be measured with the threshold value J1 set in step F1. By F4, the resin piece in which the difference value S of the arbitrary resin pieces to be measured is larger than the threshold value J1 is set as the collection target. For example, a resin piece that gives a difference value S greater than the threshold value J1 = −0.003 is determined as a collection target.

  On the other hand, a resin piece that gives a difference value S that is equal to or less than the threshold value J1 = −0.003, for example, a resin piece that gives a difference value S = −0.020, is not determined as a collection target and moves to the next step F5.

Step F5, the relationship between the transmitted X-ray intensity I _L of the difference values S and the low energy side of the resin piece, a step of comparing with the resin piece P1 and P2 contain additives which have been stored. For example, it is assumed that there is a resin piece that gives a difference value S = −0.020. The difference value S is compared with the relationship shown in Table 1 stored in advance, that is, the relationship between the thickness x and the difference value S1 of the resin piece P1 and the difference value S2 of the resin piece P2. As a result, the resin piece P1 has a thickness of 4 mm, the resin piece P2 has a thickness of 2 mm, and the difference value S1 = S2 = −0.020. Therefore, the resin piece having the difference value of −0.020 is the resin piece P1 or It cannot be determined which of the resin pieces P2.

So the difference value S transmitted X-ray intensity _{I L} of the low-energy side of the resin pieces showing a -0.020, compared with the transmitted X-ray intensity _{I L} of the low-energy side of the resin pieces P1 and P2. When the transmission X-ray intensity I _L on the low energy side of the resin piece given the difference value S = −0.020 is I _L = 3286, the transmission X on the low energy side of the resin piece P2 having a thickness of 2 mm is shown in Table 1. It can be seen that it coincides with the line intensity I _L 2 and is different from the transmitted X-ray intensity I _L 1 on the low energy side of the resin piece P1 having a thickness of 4 mm. Therefore, it can be determined that the resin piece given the difference value S = −0.020 is the resin piece P2.

  Therefore, since the resin piece P0 can be sorted and collected and the resin piece P1 and the resin piece P2 can be sorted respectively, the resin piece group in which these resin pieces are mixed can be divided into three types.

  Next, a determination method according to the comparative example will be described. FIG. 4 is a flowchart illustrating a determination method according to the comparative example. A description will be given based on the flowchart and Table 1.

  In FIG. 4, the first step F11 is a step of setting a threshold value between the difference value of the resin piece not containing the additive and the difference value of the resin piece containing the additive. For example, in the example shown above, in the case of a resin piece group composed of the resin piece P0, the resin piece P1, or the resin piece P2, as shown in Table 1, the difference value S0 = 0 of the resin piece P0 is as follows. For example, a threshold value J1 = −0.003 is set between the difference value S1 = −0.005 of the thickness 1 mm, which is the maximum value of the difference value S1 of the resin piece P1. At this time, the k value of the difference value S expressed by Equation 4 uses the ratio of the attenuation coefficient between the low energy side and the high energy side of the resin piece P0 containing no additive.

  The next step F12 is a step of calculating the difference value by measuring the transmitted X-ray intensity by irradiating the resin piece to be measured with X-rays and measuring the transmission intensity of the X-ray transmitted through the resin piece.

  The next step F13 is a step of comparing the difference value S of the resin piece to be measured with the threshold value J1. By F13, the difference value S of the resin piece is compared with the threshold value J1, and the resin piece having the difference value S larger than the threshold value J1 is set as a collection target. For example, a resin piece that gives a difference value S greater than the threshold value J1 = −0.003 is determined as a collection target.

  On the other hand, a resin piece that gives a difference value S that is equal to or less than the threshold value J1 = −0.003, for example, a resin piece that gives a difference value S = −0.020 is determined as a removal target.

  In the determination method according to the comparative example, the type of additive contained is not considered. For this reason, it will determine only by the difference of the resin piece which does not contain an additive, and the resin piece containing an additive, and cannot determine according to the kind of additive to contain. Therefore, resin pieces that do not contain an additive that is a resin piece whose difference value is larger than the threshold value are collected, but resin pieces whose difference value is equal to or less than the threshold value are collectively removed, depending on the type of additive. It cannot be removed.

  In contrast to the comparative example, in the determination method according to the present invention, considering the type of additive contained, first, the difference value of the resin piece is compared with a threshold value, and the resin piece having a difference value larger than the threshold value is It is determined that the resin piece does not contain an additive and is determined to be a collection target. Next, for the resin piece whose resin piece difference value is equal to or less than the threshold value, the relationship between the measured low-energy side transmitted X-ray intensity and the previously stored difference value and the low-energy side transmitted X-ray intensity is compared. Thus, the type of the additive is determined and selected according to the type.

  Thereby, the resin piece which concerns on the resin piece P0 which does not contain an additive, the resin piece which concerns on the resin piece P1 which contains 10 wt% glass fiber as an additive, and 1 wt% bromine (Br) as an additive is contained. Of the resin piece group consisting of the resin pieces related to the resin piece P2, three types of resin pieces related to each of P0, P1, and P2 can be selected. Here, the method of selecting the three types of resin pieces relating to P0, P1, and P2 has been described, but the difference value for the resin pieces of different thickness containing a certain additive is taken as a reference. By normalizing and repeating the operation of sequentially identifying the resin pieces containing other additives with a threshold value, the three kinds of resin pieces relating to P0, P1, and P2 are obtained. It is not limited, and there are cases where it is possible to correspond to four, five, or more types of resin pieces.

Embodiment 2. FIG.
In the first embodiment, the resin determination method according to the present invention has been described. In the second embodiment, a resin crushed piece sorting method in the used plastic recycling process using the determination method is described. To do. In the figure, the portions denoted by the numbers shown in the first embodiment are the same as the configurations described in the first embodiment, and thus the description thereof is omitted here. Hereinafter, in the case of describing as resin, description will be made mainly with a fragment of the used plastic resin in mind. The crushed pieces obtained by pulverizing used plastics are characterized in that the thickness of each crushed piece varies, and the thickness of each crushed piece varies depending on the portion. At this time, the difference value varies due to the above-described features.

  FIG. 5 is a graph showing the relationship between the thickness of a crushed piece having a known average thickness and the corresponding difference value. In the figure, the graph G evaluates the resin piece P0 containing no additive. Graph H is an evaluation of a resin piece P1 containing 10 wt% glass fiber as an additive. Graph I evaluates resin piece P2 containing 1 wt% bromine (Br) as an additive.

  The difference value S in each resin piece has a distribution reflecting the thickness distribution and the measurement error. The plot of each resin piece in the figure shows the average difference of the difference values S obtained within each resin piece. This is defined as an average difference value Sa. Further, the error bar indicates the variation of the difference value S in a predetermined thickness of the resin piece, and indicates the range that the maximum value and the minimum value of the difference value S can take.

In the equation of the difference value S expressed by Equation 4, when the value of k is set to the ratio of the attenuation coefficient between the low energy side and the high energy side of the resin piece P0, (k · μ _H −μ _L ) = 0, so that the additive The difference value S of the resin piece not containing s is ideally 0 regardless of the thickness. Accordingly, as shown in the graph G, the relationship between the thickness x of the resin piece P0 and the average difference value Sa is 0 regardless of the thickness, but the difference value S has a variation due to a measurement accidental error. It has a distribution as shown by the error bar in the middle.

On the other hand, the resin piece P1 and the resin piece P2 become (k · μ _H −μ _L ) ≠ 0 in the difference value S expression expressed by Expression 4, and the difference value S1 and the resin piece P1 are increased as the thickness x of the resin piece increases. S2 becomes smaller and has a dependency on the thickness. Further, the resin piece P1 and the resin piece P2 have different dependencies on the thickness depending on the type of additive. Accordingly, as shown by the graph H and the graph I, the relationship between the thicknesses x1 and x2 and the average difference values Sa1 and Sa2 with respect to the resin pieces P1 and P2, respectively, is also dependent on the thickness, and it is a measurement error. Reflecting the thickness distribution in the resin piece, the difference values S1 and S2 have variations and have a distribution as indicated by error bars in the figure.

  First, when determining whether the resin piece P0 does not contain an additive, the resin piece P1 containing an additive, and the resin piece P2, first, the threshold value of the difference value S is set to 0, and the thickness of the resin piece P1. An approximate determination can be made by setting a threshold value J2 between the average difference value Sa1 of 1 mm. However, in order to reliably remove the resin piece P1 and the resin piece P2, the threshold value is set as close to 0 as possible in consideration of the distribution of the difference values S1 and S2 between the resin pieces P1 and P2. However, in this case, it can be seen that the recovered amount of the resin piece P0 is reduced.

Further, as described in the first embodiment, since the resin piece P1 and the resin piece P2 cannot be determined only by setting the threshold value J2 of the difference value S, the resin piece P0, the resin piece P1, and the resin piece P2 are set to 3 can not be judged on the type, by using the relationship between the transmitted X-ray intensity I _L of the difference value S and the low energy side, it is possible to determine the resin piece P1 and the resin piece P2 regardless of the thickness. Resin piece P0, resin pieces P1, and leave the combination of low transmission X-ray intensity of the energy side I _L and the difference value S of the resin piece P2 in advance provided, the resin piece difference value of the resin piece is equal to or less than the threshold The type of additive is determined by comparing the relationship between the measured low-energy side transmitted X-ray intensity, the difference value stored in advance and the low-energy side transmitted X-ray intensity, and the resin is determined according to the type. Three types of resin pieces, that is, the piece P0, the resin piece P1, and the resin piece P2, can be selected.
Can be determined.

  Moreover, about the resin piece determined to be the resin pieces P1 and P2, the number of collection | recovery of the resin piece P0 may be increased by totaling the number for every thickness, and feeding back the total result to the setting of a threshold value. There are cases where it is possible. For example, from the counting results, the resin pieces P1 with a thickness of 1 mm and 2 mm, or the resin pieces P2 with a thickness of 1 mm are almost present in the resin piece group consisting of arbitrary pieces to be measured. If not, the threshold value J2 can be further lowered to the threshold value J3. Thereby, the collection amount of the shredded pieces that do not contain the additive that is the collection target can be increased without collecting the removal target that is the shredded piece containing the additive.

  Here, an example of a method for determining and collecting the above-described crushed pieces will be described more specifically based on a flowchart. A flowchart of the determination method is shown in FIG. In steps F21 to F25, the same steps as steps F1 to F5 described in the second embodiment are performed.

  First, as shown in step F21, a threshold value J2 of the difference value S is set between the average difference value Sa0 of the crushed pieces containing no additive and the average difference values Sa1 and Sa2 of the crushed pieces containing the additive. The Fragment pieces containing no additive (resin piece P0), crush pieces containing 10 wt% glass fiber as an additive (resin piece P1), and crush pieces containing 1 wt% bromine (Br) as an additive (resin In the case of a crushed piece group consisting of pieces P2), as shown in FIG. 5, the average difference value of 1 mm thickness in the graph G of the average difference value Sa0 of the resin piece P0 and the graph H of the average difference value Sa1 of the resin piece P1. A threshold value J2 is set at a position as close to 0 as possible in order to reliably remove the resin piece P1 between Sa and taking into account error bars indicating the distribution of the difference value S.

  After step F22 and step F23, as shown in step F24, the difference value S of the fragments and the threshold value J2 are compared. At this time, shredded pieces whose difference value S is larger than the threshold value J2 are targeted for collection. Steps F22 and F23 are the same steps as steps F2 and F3 described in the first embodiment, and a description thereof is omitted here.

  On the other hand, when the difference value S of the crushed pieces is equal to or less than the threshold value J2, the process proceeds to the next step F25 without being determined as a collection target.

Here, the transmitted X-ray intensity I _L of the difference value S and the low energy side of the debris likewise difference value S as in the first embodiment is the threshold value J2 less, previously stored difference of resin pieces P1 and resin piece P2 it can be determined by comparing the transmitted X-ray intensity I _L of the value S and the low energy side. In this way, three types of resin pieces are selected from the resin piece group composed of the resin piece P0, the resin piece P1, and the resin piece P2, and these resin pieces are removed or collected according to the application. Can do.

  Next, in step F26, the crushed pieces determined as either the resin piece P1 or the resin piece P2 are tabulated for each thickness. As a result of counting, if the crushed pieces group does not include crushed pieces having a thickness of 1 mm and 2 mm determined as the resin piece P1 or crushed pieces having a thickness of 1 mm determined as the resin piece P2, step F27. Thus, the threshold value of the difference value S can be set lower by J3, and the recovered amount of the resin crushed pieces not containing the additive corresponding to the resin piece P0 can be increased.

Embodiment 3 FIG.
In the above embodiment, the resin determination method according to the present invention has been described, but in Embodiment 3 according to the present invention, a resin sorting apparatus according to the present invention using the above determination method will be described. In the figure, the portions denoted by the numbers shown in the above embodiments are the same as the configurations described in the above embodiments, and thus the description thereof is omitted here. Hereinafter, when it is described as a resin, it is a matter of course that a new resin molded product is included. However, the present invention is an invention made from the viewpoint of plastic recycling, and is mainly a fragment of a used plastic resin. With this in mind, explain.

  A resin sorting apparatus according to Embodiment 3 of the present invention measures an X-ray irradiator that irradiates a plurality of resin pieces with X-rays, and a transmission intensity of X-rays after passing through each of the plurality of resin pieces. A detection unit is provided. The calculation unit calculates a difference value between the transmission X-ray intensity on the low energy side and the transmission X-ray intensity on the high energy side measured by the detection unit. In a storage unit composed of a memory or a hard disk, a group of resin pieces having a known thickness composed of resin pieces not containing additives in advance, and a resin piece having a known thickness consisting of resin pieces containing additives The difference value measured in each of the groups and the relationship between the difference value and the transmitted X-ray intensity on the low energy side are stored, and in the verification unit, the difference value and the measured value of the transmitted X-ray intensity on the low energy side are stored. , A difference value measured in each of a resin piece group of a known thickness consisting of a resin piece containing no pre-stored additive and a resin piece group of a known thickness consisting of a resin piece containing an additive, And the relationship between the difference value and the transmitted X-ray intensity on the low energy side is compared. Thereby, the resin piece is determined for each type of additive.

  In the determination unit, a threshold value is set between the difference value of the resin piece not containing the additive and the difference value of the resin piece containing the additive, and the resin piece not containing the additive is compared with the calculated difference value. The resin piece containing the additive is determined, and is selected by the selection unit based on the determination result.

In the counting section, the difference value and the measured value of the transmitted X-ray intensity on the low energy side, a resin piece group of a known thickness composed of resin pieces not containing additives stored in advance, and resin pieces containing additives The distribution of the material and thickness of the resin pieces obtained in the step of comparing the relationship between the difference value and the transmitted X-ray intensity on the low energy side, measured for each of the resin piece groups having a known thickness, is tabulated.
The total result of the distribution of the material and thickness of the resin piece is fed back to the determination unit and the threshold value is reset.

  Hereinafter, an example of a resin sorting apparatus according to Embodiment 3 of the present invention will be specifically described with reference to the drawings. FIG. 7 is a schematic diagram showing a sorting apparatus according to Embodiment 3 of the present invention. As shown in the figure, a resin sorting apparatus 1 is configured to supply a used plastic crushed piece from a supply unit 2 composed of a hopper and a feeder to a conveyance unit 3, for example, a conveyance unit 3 composed of a belt conveyor or the like. Transport the fragments. The crushed pieces 20 conveyed by the conveying unit 3 are irradiated with X-rays from the X-ray irradiation unit 4 after jumping out on the conveying unit 3 or the conveying unit 3, and transmitted through the crushed pieces among the irradiated X-rays. X-rays are measured by the X-ray detection unit 5 including a dual sensor. Based on the transmitted X-ray intensity detected by the X-ray detection unit 5, the control unit 6 determines whether the fragment is to be collected or to be discarded. The sorting unit 7 sorts the crushed pieces based on the information from the control unit 6.

  The control unit 6 is based on the image reading unit 10 that reads image data from the X-ray detection unit 5 and the low-energy side and high-energy side transmission X-ray intensity data obtained by the X-ray detection unit 5. A calculation unit 11 for calculating a difference value of transmitted X-ray intensities on the energy side and the high energy side, a resin piece group not containing an additive, a first resin piece group containing a first additive, and a second The difference value about the resin piece from which thickness differs which comprises each of the 2nd resin piece group containing the additive of this, and the memory | storage part by which the relationship between a difference value and the transmission X-ray intensity on the low energy side was memorize | stored 12, collating unit 13 for comparing and collating data stored in storage unit 12 with data of calculation unit 11 obtained by actual measurement, crushing pieces to be collected based on the result of collating unit 13, or crushing to be discarded And a determination unit 14 for determining whether it is a piece To have.

  The selection unit 7 mainly uses, for example, an air gun or the like to select or change the direction (trajectory) of the crushed pieces 20 in order to remove or collect the crushed pieces 20 to be sorted in the air. 8. A recovery unit 9 having a small room divided into a plurality of compartments for storing the fragment 20 to be collected and the fragment 20 to be removed is provided.

  Next, the operation of the above-described resin sorting apparatus 1 will be specifically described with reference to FIG. The crushed pieces 20 stored in the supply unit 2 are supplied to the conveyance unit 3 configured by a conveyance belt or the like. The crushed pieces 20 include, for example, crushed pieces 201 containing no additive, crushed pieces 202 containing glass fibers, and crushed pieces 203 containing bromine (Br). The crushed pieces 20 supplied to the transport unit 3 are transported by the transport unit 3 and pass between the X-ray irradiation unit 4 and the X-ray detection unit 5 on the transport unit 3 or in the air jumping out of the transport unit 3. Sometimes, X-rays are irradiated from the X-ray irradiation unit 4, and X-rays transmitted through the fragment 20 are detected by the X-ray detection unit 5.

  In the control unit 6, based on the data relating to the transmitted X-ray intensity obtained by the X-ray detection unit 5, whether each of the crushed pieces 20 is a crushed piece to be recovered or a crushed piece to be discarded. It is judged and sorted by the sorting unit 7 based on the judgment result. Here, the crushed pieces 202 and crushed pieces 203 that are defined as crushed pieces to be removed are selectively removed from the collection unit 9 by operating the selection unit 8 such as an air gun that injects air sent from an air cylinder. Drop it into the area that should be. On the other hand, the crushed pieces 201 that are defined to be collected are allowed to pass without operating the selection unit 8 and dropped to the area to be collected.

  Note that, by configuring the selection unit 8 with a plurality of air guns, it is possible to drop a plurality of types of crushed pieces of resin to be sorted into different regions. For example, when the crushed pieces 201 to 203 are divided into different areas, a first air gun 801 that sorts the crushed pieces 202 and a second air gun 802 that sorts the crushed pieces 203 are provided. When the air gun 801 is operated, the crushed piece 202 is dropped into the first region 901, and when the second air gun 802 is operated, the crushed piece 203 is dropped into the second region 902, When the first air gun 801 and the second air gun 802 are passed without being operated, it is possible to set so that the fragment 201 is dropped in the third region 903.

  Next, the determination operation in the control unit 6 will be described. The calculation unit 11 calculates a difference value based on the transmitted X-ray intensity on the low energy side and the transmitted X-ray intensity on the high energy side acquired from the X-ray detector 5. The memory | storage part 12 measured with each of the resin piece group of the known thickness which consists of the resin piece of known thickness which consists of the resin piece which does not contain an additive, and the resin piece which contains the additive. And the relationship of the transmitted X-ray intensity on the low energy side is stored, and the collation unit 13 compares the data stored in the storage unit 11 in advance with the data of the calculation unit 11 obtained by actual measurement, and the difference value is greater than the threshold value. If it is larger, the determination unit 14 determines that it is a collection target, and the collection unit 9 collects it.

  Comparing the calculated difference value with the threshold value, if the difference value is equal to or less than the threshold value, the resin piece not containing the additive stored in the storage unit 12, the resin piece containing 10 wt% glass fiber as the additive, and The relationship between the difference value measured with a resin piece group of a known thickness consisting of a resin piece containing 1 wt% bromine (Br) as an additive and the transmitted X-ray intensity on the low energy side, or the calculated difference value and low By comparing the relationship of the transmitted X-ray intensity on the energy side, a crushed piece 202 containing 10 wt% glass fiber as an additive and a crushed piece 203 containing 1 wt% bromine (Br) as an additive are determined. can do. Therefore, the resin pieces of the three kinds of resins can be removed and collected from the crushed pieces group.

Embodiment 4 FIG.
In the above-described third embodiment, an example of a resin sorting device has been described. In the fourth embodiment, another example of a resin sorting device will be described. FIG. 8 is a schematic diagram showing an example of a sorting apparatus according to Embodiment 4 of the present invention. As shown in the figure, the numbered portions shown in the example of the resin sorting apparatus according to Embodiment 3 of the present invention are the same as the configuration described in the example of the resin sorting apparatus. The description is omitted here.

  The difference from the sorting apparatus according to the third embodiment is that the control unit 6 includes a totaling unit 15 that totals the determination results of the collation unit 13 and a feedback unit 16 that transmits the totaling results of the totaling unit 15 to the determination unit 14. It is to have.

  Hereinafter, the determination operation in the control unit 6 will be described. Since the description of the portion described in the example of the resin sorting apparatus according to the third embodiment is repeated, the description thereof is omitted here. The memory | storage part 12 measured with each of the resin piece group of the known thickness which consists of the resin piece of known thickness which consists of the resin piece which does not contain an additive, and the resin piece which contains the additive. And the relationship of the transmitted X-ray intensity on the low energy side is stored, and the collation unit 13 compares the data stored in the storage unit 12 in advance with the data of the calculation unit 11 obtained by actual measurement, and the difference value is smaller than the threshold value. If it is larger, the determination unit 14 determines that it is a collection target and the collection unit 9 collects it.

  The collation unit 13 transmits data related to the determination result to the totaling unit 15. The totaling unit 15 totals the data related to the transmitted determination results for a predetermined period, and transmits the totaled results to the feedback unit 16. The feedback unit 16 transmits the aggregation result to the determination unit 14, and the determination unit 14 resets the threshold value based on the aggregation result. The aggregation unit 15 may aggregate data related to the determination result and transmit the aggregation result to the determination unit 14.

  For example, the crushed piece 202 containing 10 wt% glass fiber as the additive described in Embodiment 3 and the crushed piece 203 containing 1 wt% bromine (Br) as the additive will be specifically described. For example, the data based on the thickness of the crushed pieces 202 and the crushed pieces 203 obtained by the determination unit 14 are totaled by the totaling unit 15. As a result, when the crushed piece 202 does not include a piece having a thickness of 1 mm or 2 mm, and when the crushed piece 203 does not contain a piece having a thickness of 1 mm, the determination unit 14 determines the difference value. By resetting the threshold value low, it is possible to increase the amount of resin fragments that do not contain additives.

  As described above, according to the resin sorting apparatus according to the above embodiment, the resin for each type of additive can be obtained by comparing the relationship between the transmitted X-ray intensity on the low energy side and the difference value with the existing information. You can sort pieces. Moreover, the resin piece and additive which do not contain an additive are included based on the distribution information which concerns the resin piece for every kind of additive by comparison with the existing information and the relationship between the transmission X-ray intensity on the low energy side and the difference value By adjusting the threshold value of the resin piece, it is possible to increase the amount of the resin piece that does not contain the additive.

  DESCRIPTION OF SYMBOLS 1 Sorting device, 2 Supply part, 3 Conveyance part, 4 X-ray irradiation part, 5 X-ray detection part, 6 Control part, 7 Sorting part, 8 Selection part, 9 Collection | recovery part, 10 Image reading part, 11 Calculation part, 12 Storage unit, 13 verification unit, 14 determination unit, 15 counting unit, 16 feedback unit, 20 crushed piece, 201 crushed piece not containing additive, 202 crushed piece containing glass fiber, 203 crushed containing bromine (Br) Fragment

Claims (4)

A resin piece group composed of a plurality of resin pieces having a predetermined thickness, the resin piece group containing no additive, the first resin piece group containing the first additive, and the second additive In the second resin piece group containing
Each resin piece constituting each resin piece group is irradiated with X-rays, and a difference value that is a difference between the transmitted X-ray intensity on the low energy side and the X-ray intensity on the high energy side, and the difference value and transmission Record the relationship with the X-ray intensity on the low energy side in advance,
A difference value which is a difference between the X-ray intensity on the low energy side and the X-ray intensity on the high energy side, which is irradiated with X-rays on an arbitrary resin piece, and the X-ray on the low energy side which is transmitted with the difference value By determining the relationship with the intensity, and comparing the difference value recorded in advance and the relationship between the difference value and the transmitted X-ray intensity on the low energy side, the content and type of the additive in the arbitrary resin piece A method for determining resin ,
Addition of μNL to the low energy side attenuation coefficient of resin pieces not containing additives, μNH to the high energy side of resin pieces not containing additives, and addition of low energy side attenuation coefficients to resin pieces containing no additives The ratio of the resin piece not containing the agent to the attenuation coefficient on the high energy side is k = μNL / μNH, the transmitted X-ray intensity on the low energy side is IL, the X-ray intensity on the irradiated low energy side is IL0, and the transmitted high When the X-ray intensity on the energy side is IH and the X-ray intensity on the irradiated high energy side is IH0, the difference value is ln (IL / IL0) −k · ln (IH / IH0). Judgment method. A threshold value is provided between the difference value relating to the resin piece constituting the resin piece group not containing the additive and the difference value relating to the resin piece constituting the first resin piece group and the second resin piece group,
It is determined whether or not any resin piece contains an additive depending on whether or not a difference value related to any resin piece is equal to or less than the threshold value.
The resin determination according to claim 1, wherein when the difference value related to an arbitrary resin piece is equal to or less than the threshold value, the type of additive is determined based on the relationship between the difference value and the transmitted X-ray intensity on the low energy side. Method.   The resin determination method according to claim 2, wherein the threshold is reset based on determination results of a plurality of arbitrary resin pieces to be selected. An X-ray irradiation unit for irradiating an arbitrary resin piece with X-rays;
An X-ray detector that detects the intensity of X-rays transmitted through the arbitrary resin piece;
A calculation unit that calculates a difference value between the transmission X-ray intensity on the low energy side detected by the X-ray detection unit and the transmission X-ray intensity on the high energy side;
A resin piece group composed of a plurality of resin pieces having a predetermined thickness, the resin piece group containing no additive, the first resin piece group containing the first additive, and the second additive A difference value for the resin pieces having different thicknesses that constitute each of the second resin piece group containing, and a storage unit that stores in advance the relationship between the difference value and the transmitted X-ray intensity on the low energy side,
The difference value obtained by irradiating the arbitrary resin piece with X-rays by the calculation unit, the relationship between the difference value and the transmitted X-ray intensity on the low energy side, and the difference value stored in the storage unit, And a determination unit that compares the relationship between the difference value and the transmitted X-ray intensity on the low energy side,
Based on the determination result of the determination unit, any one of the resin piece in which the arbitrary resin piece does not contain an additive, the resin piece containing the first additive, and the resin piece containing the second additive a sorting device for resin sorting or is,
Addition of μNL to the low energy side attenuation coefficient of resin pieces not containing additives, μNH to the high energy side of resin pieces not containing additives, and addition of low energy side attenuation coefficients to resin pieces containing no additives The ratio of the resin piece not containing the agent to the attenuation coefficient on the high energy side is k = μNL / μNH, the transmitted X-ray intensity on the low energy side is IL, the X-ray intensity on the irradiated low energy side is IL0, and the transmitted high When the X-ray intensity on the energy side is IH and the X-ray intensity on the irradiated high energy side is IH0, the difference value is ln (IL / IL0) −k · ln (IH / IH0). Sorting device.

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