JPH1065284A - Method and apparatus for decomposing polymeric material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regenerate raw rubber from rubber pieces by selecting a laser beam of a wavelength which resonates to a stretching vibration of a specific molecular bond of a polymeric material from variable-wavelength mid infrared region laser beams and emitting it on the polymeric material, and selectively decomposing the specific molecular bonds of the polymeric material and decomposing the polymeric material. SOLUTION: A specific semiconductor device which produces a laser beam, having a wavelength resonating to the stretching vibration of the specific molecular bond of a rubber piece 5 to be composed is selected out of each semiconductor devices 2a, 2b,.... In the case of a benzyldisulfide having S-S bonds for example, the wavelength of the stretching vibration of its specific molecular bond is 13.2μm, and a rubber piece 5 of a polymeric material having an S-S bonds is decomposed by emitting a laser beam matching the vibration wavelength for selectively decomposing the specific molecular bonds by resonance. In this case, it is possible to regenerate the decomposed rubber piece 5 into original raw rubber, since decomposition is performed by selecting a wavelength which resonates to the stretching vibration of the S-S bonds of the sulfur S of the polymeric material of the benzyldisulfide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for decomposing a polymer material by breaking a specific molecular bond of the polymer material.

[0002]

2. Description of the Related Art Most of polymeric materials, especially rubber products, are automobile tires, and many old tires are disposed of every year. Disposal of old tires causes a great environmental problem, and recycling thereof is desired. However, at present, it is equivalent to being left without economical and effective means.

[0003] Even if it is used tires, various types of rubber polymer components are included in the tires. For example, there are many types such as nitrile rubber and butyl rubber. The raw rubber, which is the raw material of rubber, is a thread-like high polymer having a molecular weight of 100,000 or more. It is not an elastic material by itself, and the rubber molecules slip by chemically cross-linking or vulcanizing the rubber molecules. Is prevented at the cross-linking point, and the property as an elastic body is given.

[0004] As a method of regenerating such a rubber tire, a method of changing to a reclaimed rubber is generally used. Reclaimed rubber is obtained by physically or chemically treating a crosslinked or vulcanized rubber and adding a pressure-sensitive adhesive and a plasticizer again to make the rubber similar to the raw rubber or the unvulcanized rubber.

[0005]

However, the above-mentioned recycled rubber is used as a substitute for raw rubber or as a rubber compounding agent because of its low price. When the recycled rubber is mixed with the new rubber and used, the mixing time can be reduced and the workability can be improved.

However, wear resistance, fatigue resistance, or water absorption resistance is deteriorated, and it becomes tattered in a shorter time than that made of only new rubber. Not.

The present invention has been made in view of the state of the art of old tire recycling described above, and uses a laser beam of a specific wavelength to cut a specific molecular bond such as an SS bond of rubber to convert a polymer material. It is an object of the present invention to provide a method and an apparatus for decomposing a polymer material which can be decomposed and can recover characteristics as a raw material.

[0008]

According to the present invention, as a means for solving the above problems, a laser beam having a wavelength that resonates with stretching vibration of a specific molecular bond of a polymer material is selected from a wavelength-variable mid-infrared laser beam. Then, the polymer material is irradiated, and a specific molecular bond of the polymer material is selectively decomposed to decompose the polymer material.

Further, as a device for carrying out this method, a laser device for generating a laser light of a tunable mid-infrared region is provided. A polymer material decomposer that irradiates the polymer material placed on the support means with light to selectively decompose specific molecular bonds to decompose the polymer material can be employed. .

The invention of the method and apparatus for decomposing a polymer material is based on the premise that the laser beam is tunable in the mid-infrared region. A laser beam having a wavelength that resonates with stretching vibration of a specific molecular bond of the polymer material is selected from such a wavelength-variable laser beam. In the case of polymer rubber such as automobile tires, a specific molecule of a polymer material is obtained by selecting and irradiating a wavelength that resonates with the stretching vibration of the SS bond of an elastic rubber formed by crosslinking or vulcanizing a polymer raw rubber. By selectively breaking bonds,
The polymer material is decomposed and the raw rubber is regenerated.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of the polymer material decomposition apparatus according to the first embodiment. A plurality of semiconductor laser elements 2 (in the illustrated example, 2a, 2b,...)
2n, 2o) are arranged on the circumference at predetermined intervals,
A galvanometer mirror 3 is provided at the center position.
The galvanomirror 3 is rotated by a pulse motor 4 to select one of the semiconductor laser elements 2, and the laser beam of the selected laser element 2 is transmitted to a rubber piece 5 of a polymer material via a transmission system 6 for irradiation. It is configured to be. Reference numeral 7 denotes a tray for receiving the polymer powder decomposed from the rubber pieces 5.

The fixed substrate 1 is supported by suitable means (not shown). Semiconductor laser device 2 (2a, 2b,..., 2)
n, 2o) consist of a heterojunction semiconductor device, and have a mid-infrared light region (wavelength: 4.5 to 14 μm) using PbSnTe (active layer) / PbSnTe (cladding layer) as a sandwich layer between the active layer and the cladding layer It is a semiconductor element that generates laser light.

Each of the semiconductor elements 2a, 2a
b,... 2n and 2o generate laser beams having wavelengths different by 0.2 μm. As described above, in order to make the wavelength slightly different, each element can cover the above wavelength band by changing the mixed crystal ratio of PbTe and SnTe. Although not shown, each of the semiconductor elements 2a, 2
Power is supplied to b,... from a common power supply unit, and power is supplied to a specific semiconductor element selected by a command from the control unit 10 to generate power. FIG. 2 is a partial cross-sectional side view of the device, showing the relationship between the transmission system 6 and the substrate 1.

The rubber piece of the automobile tire made of the polymer material is disassembled by the apparatus having the above structure. When the rubber piece is decomposed by this device, the wavelength of the laser beam generated from each of the semiconductor elements 2a, 2b,... Matches or is very close to the wavelength that resonates with the specific molecular bond stretching vibration of the rubber piece to be decomposed. This is performed by selecting a specific semiconductor element to be used.

For example, Benzyl disulfide having an SS bond has a specific molecular bond stretching vibration wavelength of 13.2 μm. When a laser beam matching the vibration wavelength is irradiated, specific molecular bond is excited by resonance. A rubber piece of a polymer material having an SS bond is decomposed so that is selectively decomposed. In this case, the sulfur S of the polymer material of the above-mentioned benzyl disulfide is S
The decomposition is performed by selecting a wavelength that resonates with the stretching vibration of the -S bond, and does not decompose even the bonds between polymers other than the S-S bond. Therefore, the decomposed rubber pieces are regenerated as raw materials similar to the original raw rubber.

The specific molecular bond stretching vibration refers to the bond between polymers of each polymer material, particularly the SS bond of a crosslinked or vulcanized polymer in a rubber piece, fluctuates at a specific temperature state. Vibrates at a specific frequency depending on the type of the polymer material.

The wavelength of the molecular bond stretching vibration of the above-mentioned specific polymer material is measured in advance by a Fourier transform infrared spectrometer, and the specific wavelength is input from the outside to the control unit 10 to rotate the motor 4. , Or any of the semiconductor elements 2a, 2b,...

The polymer powder decomposed from the rubber pieces 5 by this method is received by the tray 7 and collected in a predetermined amount.
Although not shown, the rubber piece 5 can be slightly displaced up, down, left, right, up and down around the center position of the transmission system 6 by means for supporting the rubber piece 5 in order to disassemble it evenly.

In the above embodiment, the fixed substrate 1 is fixed, and the galvanomirror 3 is rotated by the motor 4 to select a semiconductor element having a specific wavelength.
Alternatively, a fixed mirror may be provided, and the fixed substrate 1 may be used as a rotating substrate and rotated by the motor 4 to select a semiconductor element having a specific wavelength.

Further, in the above two embodiments, a device which generates a laser beam of a specific wavelength is selected from a plurality of semiconductor devices shifted by a predetermined wavelength pitch. Alternatively, a free electron laser may be used. Good.

In a free electron laser, an electron beam emitted from an electron gun is accelerated by an accelerator to near the speed of light, and when the electron beam follows a magnetic field forming means in which a magnetic field periodically changes, the meandering magnetic field is generated. The laser light having a desired wavelength can be obtained by amplifying the light generated by the cooperative action of the above by an optical resonator.

In such a free electron laser, by changing one or both of the intensity of the magnetic field and the energy level of the electron beam, laser light of any wavelength from ultraviolet to infrared can be obtained. The same effect can be obtained by generating a desired wavelength and laser light by changing the magnetic field strength or changing the acceleration energy by an electron beam accelerator and irradiating the rubber piece 5 with the laser light.

[0023]

As described above in detail, this polymer material decomposition apparatus irradiates a polymer material with a laser beam tunable in the mid-infrared region to resonate with the specific molecular bond stretching vibration wavelength. Since the polymer material is decomposed, the raw material such as raw rubber can be regenerated by decomposing the polymer material by this apparatus, for example, by decomposing the S—S bond in the case of a rubber piece, Characteristics such as abrasion resistance, fatigue resistance, and water absorption resistance can be improved, and a great effect of enabling recycling to automobile tires can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a polymer material decomposition apparatus according to an embodiment.

FIG. 2 is a partial cross-sectional side view of the same device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed substrate 2 Semiconductor laser element 3 Galvano mirror 4 Motor 5 Rubber piece 6 Transmission system 7 Tray

Claims (4)

[Claims] 1. A laser beam having a wavelength that resonates with stretching vibration of a specific molecular bond of a polymer material selected from a wavelength-variable mid-infrared laser beam, and the polymer material is irradiated with the selected laser beam. Selectively decomposing the polymer material to decompose the polymer material. 2. A laser device for generating a laser light of a tunable mid-infrared region is provided, and a laser beam having a wavelength that resonates with stretching vibration of a specific molecular bond of a polymer material is provided from the laser device.
An apparatus for decomposing a polymer material, which irradiates the polymer material placed on a support means and selectively decomposes specific molecular bonds to decompose the polymer material. 3. The mid-infrared laser device according to claim 1, wherein the mid-infrared laser device is a mid-infrared laser generating device in which the wavelength is tunable by selectively using any one of a plurality of laser light generating means having different wavelengths. Item 3. A polymer material decomposition apparatus according to Item 2. 4. The polymer material decomposition apparatus according to claim 2, wherein the mid-infrared laser device is a free electron laser generator.