JPH09297114A - Method of judging plastic material, and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily, quickly and continuously perform a material judgment by emitting an infrared ray to plastics, thereby causing a plastic surface temperature difference because the absorptivity of infrared ray is differed between materials, and measuring the temperature difference by a temperature measuring device. SOLUTION: An infrared ray emitting device 1 and a temperature measuring device 2 are arranged above a transfer device 3. A plastic 4 to be measured is placed on the transfer device 3 and transferred. A sorting device 6 is arranged on the downstream side of the transfer device 3. When the plastic 4 is passed through the infrared ray emitting zone by the infrared ray emitting device 1 for a fixed time, a fixed infrared ray is emitted thereto, and the plastic 4 shows a temperature rise according to the absorptivity of the respective materials by the natural infrared ray absorptivity. A judgment device 5 compares the measured temperature of the plastic 4 measured by the temperature measuring device 2 with a known data to judge the material of the plastic 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic material discriminating method and its device. Specifically, when processing or recycling various plastic wastes such as plastic bottles such as soft drinks and plastic packaging bags for foods, etc. Regarding the device.

[0002]

2. Description of the Related Art A large amount of various plastics such as soft drinks and other plastic bottles and food packaging bags are discarded as waste after use. In recent years, from the viewpoint of global environmental problems and effective use of resources, reuse of wastes and the like is desired in various industrial fields.

For plastic bottles such as soft drinks,
The recycling of bottles made of polyethylene terephthalate (hereinafter abbreviated as PET) is being commercialized. In the recycling of waste PET bottles, it is important to have a technique of selecting PET bottles from collected waste bottles in which different material bottles are mixed.

Other than PET, bottle materials include polyethylene (hereinafter abbreviated as PE), polypropylene (hereinafter abbreviated as PP), polystyrene (hereinafter abbreviated as PS), polyvinyl chloride (hereinafter abbreviated as PVC), and the like.

As a method of discriminating the material, a method based on specific gravity, X
Method for measuring the amount of linear transmission (Shokai Sho 60-187711)
No.), a method of measuring the absorption spectrum of infrared rays or near-infrared rays and comparing it with known data to make a discrimination (JP-A-6-12).
No. 3701, JP-A-6-210632, etc.) and a method of calculating the thermal diffusivity by raising the material temperature by laser beam irradiation and measuring infrared rays reflected, and comparing with known data to make a distinction (Japanese Patent Laid-Open Publication No. HEI-HEI). 5-312742
issue).

[0006]

However, the above-mentioned conventional discrimination method has the following problems. In the discrimination by specific gravity, PE, PP, which has a large specific gravity difference from PET,
PS, etc. can be separated, but P with a small difference in specific gravity from PET
It is difficult to identify with VC. Further, the method of measuring the amount of X-ray transmission has a problem that it is mistakenly recognized due to the difference in the shape of the bottles, the overlapping due to crushing, etc.

Further, in the method of utilizing the absorption spectrum of infrared rays or near infrared rays, there are cases where it is difficult to measure the absorption spectrum due to overlapping due to crushing of bottles and dirt on the inner surface of the waste bottle. In addition, since the absorption spectrum is measured and compared with known data to make a distinction, there is a limit in increasing the processing speed.

On the other hand, in the method of irradiating a laser beam to calculate the thermal diffusivity, a special device such as a laser irradiating device is required, and in addition, the thermal diffusivity is calculated from the temperature rise degree. Is not suitable for the object to be measured, which has a non-uniform shape such as the material discrimination of waste bottles.

Further, since the laser beam is applied to a minute spot to detect infrared rays at the same point, the object to be measured needs to be fixed, and continuous processing such as bottle discrimination on the line is difficult. is there.

[0010]

In the plastic material discrimination method of the present invention, the surface temperature of the plastic is raised by irradiating the plastic of unknown material with infrared rays, and the temperature is measured to discriminate the material. It is characterized by

Further, the plastic material discriminating apparatus of the present invention which achieves the above object, is an infrared irradiating device for irradiating plastic of unknown material with infrared rays, a temperature measuring device for measuring the temperature of the plastic surface, and a measured plastic surface. And a discriminator that determines the material based on the temperature.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, when plastics are irradiated with infrared rays, there is a difference in the absorption rate of the infrared rays among the materials, so that a plastic surface temperature difference occurs and the temperature difference is measured by a temperature measuring device. By doing so, the plastic material can be determined.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 1 shows a plastic material discriminating apparatus according to an embodiment of the present invention.

As shown in the figure, an infrared irradiation device 1 and a temperature measuring device 2 are arranged above the transfer device 3, while a plastic 4 to be measured is placed on the transfer device 3 in the direction of the arrow. Be transferred to. A sorting device 6 is arranged on the downstream side of the transfer device 3, and the transferred measured plastic 4 reaches the sorting device 6.

As the infrared irradiating device 1, a device for generating light rays in the infrared wavelength region can be widely adopted, and for example, an infrared heater or the like can be used. Infrared irradiation device 1
In addition, by providing a variable controller or a multi-stage controller that adjusts the infrared irradiation intensity, the rate of temperature rise of the measured plastic 4 can be controlled.

As the temperature measuring device 2, as a detector,
Vacuum thermocouples, pyroelectric infrared sensors or radiation thermometers can be used. The temperature measuring device 2 measures the temperature of the measured plastic 4 after being irradiated with a constant infrared ray, and sends the measured temperature to the discriminator 5.

As the transfer device 3, a device for continuously traveling or intermittently transferring the measured plastic 4 can be used. As the plastic 4 to be measured, it is preferable to use a material whose material is unknown, and in particular, a molded product having the same shape and thickness.

The discriminator 5 discriminates the material of the measured plastic 4 by comparing the measured temperature of the measured plastic 4 measured by the temperature measuring device 2 with known data.

Here, the measured plastic 4 is irradiated with a certain amount of infrared light when passing through the infrared irradiation zone by the infrared irradiation device 1 for a certain time, and the infrared absorption rate peculiar to each plastic material causes the absorption rate of each material to vary. Shows a rise in temperature. A specific example is shown in FIG. FIG. 2 shows that a PET bottle and a PVC bottle are irradiated with infrared rays using an infrared heater,
This is an example of measuring the surface temperature with an infrared radiation thermometer.
In FIG. 2, the horizontal axis is the infrared irradiation time and the vertical axis is the surface temperature of the bottle.

As shown in FIG. 2, PET bottle and PVC
The difference in temperature between the bottle and the bottle occurs due to the difference in infrared absorption rate, and the PET bottle is higher than the PVC bottle by about 20 ° C. from the initial stage of infrared irradiation.

Therefore, the discriminator 5 can determine the material by comparing the surface temperature of the plastic with a reference value set in advance for each material, or by the difference in the measured temperature between the reference material and different materials. The sorting device 6 can sort the plastics 4 to be measured based on the result of the discriminator 5, and in the above example, the PET bottle and the PVC bottle can be sorted.

As described above, in the present embodiment, the fact that the plastic material has a unique infrared absorption rate is used to irradiate the plastic of unknown material with a certain amount of infrared rays, and it varies depending on the material. The plastic material can be discriminated by measuring the temperature rise and comparing the measured temperature or the measured temperature with a reference value or the temperature difference between different materials.

Further, in this embodiment, by using infrared rays as the irradiation light, it is possible to discriminate the plastic material easily, rapidly and continuously. In this embodiment, the temperature was measured on the downstream side of the infrared irradiation device 1 after the infrared irradiation for a predetermined time.
Instead of using, the temperature may be measured at the place after the infrared irradiation for a predetermined time, or the temperature may be measured at the same time as the infrared irradiation.

[0024]

As described above in detail with reference to the embodiments, the present invention irradiates the plastic to be measured with infrared rays by the infrared irradiation device and then measures the temperature of the surface of the plastic to be measured by the temperature measuring device. The material determination can be performed easily, quickly, and continuously by measuring with.

[Brief description of drawings]

FIG. 1 is a structural diagram of a plastic material discriminating apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between infrared irradiation time and bottle surface temperature.

[Explanation of symbols]

 1 Infrared irradiation device 2 Temperature measurement device 3 Transfer device 4 Plastic to be measured 5 Discriminator 6 Sorting device

Claims (9)

[Claims] 1. A method for determining a plastic material, which comprises irradiating infrared rays to a plastic of an unknown material to raise the surface temperature of the plastic and measuring the temperature to determine the material. 2. The plastic material discrimination method according to claim 1, wherein the plastic is a molded product having the same shape and thickness. 3. An infrared irradiation device for irradiating a plastic of unknown material with infrared rays, a temperature measuring device for measuring the temperature of the plastic surface, and a discriminator for judging the material based on the measured plastic surface temperature. Characteristic plastic material identification device. 4. The plastic material discrimination device according to claim 3, wherein the plastic is a molded product having the same shape and thickness. 5. The plastic material discriminating apparatus according to claim 3 or 4, wherein the discriminator judges the material by comparing the surface temperature of the plastic with a reference value preset for each material. . 6. The material according to claim 3, wherein the discriminator judges the material by comparing the surface temperature of the plastic with a reference material and a measured temperature difference between different materials. Plastic material identification device. 7. The plastic material discriminating apparatus according to claim 3, 4, 5 or 6, wherein the plastic is continuously or intermittently fed. 8. The temperature of the plastic is measured after being irradiated with infrared rays for a predetermined time, or the temperature is measured at the same time when the plastic is irradiated with infrared rays.
The plastic material discrimination device according to 4, 5, or 6. 9. The plastic material discriminating apparatus according to claim 3, wherein the temperature of the plastic is irradiated with infrared rays for a predetermined time and then the temperature is measured on the downstream side of the infrared irradiation apparatus.