JPH09169982A - Treatment of plastic waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate two kinds of plastics in a method for treating a plastic waste comprising a hydrocarbon-based plastic and a non-hydrocarbon-based plastic. SOLUTION: Only a hydrocarbon-based plastic contained in a plastic waste comprising the hydrocarbon-based plastic and a non-hydrocarbon-based plastic is selectively dissolved in a dividing solvent dissolving the hydrocarbon-based plastic but substantially not the non-hydrocarbon-based plastic by bringing the waste into contact with the solvent. The dividing solvent solution having dissolved the hydrocarbon-based plastic is separated from the non-hydrocarbon- based plastic in a solid state. The dividing solvent solution of the hydrocarbon- based plastic is decomposed to give a decomposed product oil. The decomposition product oil is used as at least a part of the dividing solvent. The dividing solvent is composed of a liquid hydrocarbon mixture of an aromatic hydrocarbon and a paraffinic hydrocarbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating plastic waste composed of a hydrocarbon plastic and a different hydrocarbon plastic.

[0002]

2. Description of the Related Art PE (polyethylene), PP (polypropylene), PS (polystyrene), PVC (polyvinyl chloride), PET (polyethylene terephthalate) and A
BS resin (acrylonitrile / butadiene / styrene copolymer) is widely used as a general-purpose plastic. Therefore, the majority of plastic waste consists of these plastics. At present, most of plastic waste is incinerated or landfilled without being reused, but such treatment is not desirable in terms of resource saving. Until now, various methods have been proposed for reusing plastic waste. One of the typical methods is a method of thermally decomposing oil into oil (pyrolysis oiling method). ing. In this method, a plastic waste is heated to a high temperature of about 450 ° C. to generate a cracked oil. In this pyrolysis oilification method, when the plastic waste as a raw material to be treated consists of only hydrocarbon plastics such as PE, PP, PS, etc., problems such as blockage troubles and corrosion of plants and pipes occur. It can be easily implemented without occurring. However, the raw materials to be processed are PE, P
Hydrocarbon plastics such as P and PS, and PVC and PE
When it is made of a mixture with a different hydrocarbon-based plastic such as T or ABS resin, various problems occur, and it is difficult to safely and stably perform the operation. For example, PVC
When mixed with hydrogen chloride, highly corrosive hydrogen chloride is generated, causing corrosion of equipment and piping. When PET is mixed, phthalic acids are generated by its thermal decomposition, and this causes a piping blockage trouble. When ABS resin is mixed, toxic hydrogen cyanide is generated by its thermal decomposition. As described above, when plastic waste is converted to pyrolysis oil, it is desirable to remove the different hydrocarbon-based plastics from the waste in advance. There is no known industrially advantageous method for separating hydrogen-based plastics from plastics, and there are many practical applications of methods for thermally decomposing plastic waste containing hydrocarbon-based plastics and different hydrocarbon-based plastics into oil. Difficulties have arisen.

[0003]

DISCLOSURE OF THE INVENTION The present invention is industrially advantageous in a method for treating a plastic waste consisting of a hydrocarbon type plastic and a different hydrocarbon type plastic, which includes a step of separating these two types of plastics. The task is to provide a new method.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, in a method for treating a plastic waste consisting of a hydrocarbon-based plastic and a different hydrocarbon-based plastic, (i) dissolving the hydrocarbon-based plastic in the waste, A dissolution step in which only a hydrocarbon plastic contained in the waste is selectively dissolved by contacting with a separation solvent which is substantially insoluble, (ii) the dissolution product obtained in the dissolution step is carbonized. A solid-liquid separation step of separating a separation solvent solution in which hydrogen-based plastic is dissolved and a solid different hydrocarbon-based plastic, (iii) decomposition of the separation solvent solution of the hydrocarbon plastic obtained in the solid-liquid separation step Let me
A cracking step for obtaining a cracked product oil is included, and a part of the cracked product oil obtained in the cracking step is used as at least a part of the fractionating solvent in the dissolving step, and the fractionating solvent is an aromatic hydrocarbon. And a liquid hydrocarbon mixture containing paraffinic hydrocarbons are provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The plastic waste used as a raw material to be treated in the present invention comprises a hydrocarbon plastic and a different hydrocarbon plastic. Hydrocarbon plastics include polyolefin plastics such as PE and PP and aromatic plastics such as PS, and different hydrocarbon plastics include PVC, PET and ABS resins. All of these plastics are general-purpose plastics that are produced in large quantities, and the bulk of plastic waste consists of these plastics. Of course, the plastic waste can contain hydrocarbon plastics and different hydrocarbon plastics other than the above-mentioned plastics, but the ratio is
Usually, it is 25% by weight or less. In general plastic waste, the proportion of hydrocarbon plastic is usually 50% by weight or more, and in some cases 75% by weight.
That is all.

The fractionating solvent of the present invention comprises a liquid hydrocarbon mixture containing an aromatic hydrocarbon and a paraffinic hydrocarbon, and selectively dissolves only the hydrocarbon plastic, while the different hydrocarbon plastic is substantially dissolved. It does not dissolve in. It has been discovered for the first time by the present inventors that such a mixture solvent exhibits an excellent effect as a solvent for separating plastic waste. Moreover, such a solvent mixture has the advantage of being inexpensive because it can be easily prepared by using the produced oil obtained by pyrolyzing the hydrocarbon plastic contained in the plastic waste.

The proportion of aromatic hydrocarbons contained in the fractionating solvent is 5 to 70%, preferably 8 to 65%. When the proportion of the aromatic hydrocarbon exceeds the above range, a substantial amount of the different hydrocarbon-based plastic, particularly PVC, will be dissolved. On the other hand, when the proportion is less than the above range, the hydrocarbon-based plastic, particularly PS Substantially does not dissolve. The ratio of paraffinic hydrocarbon is 5 to
It is 85%, preferably 10 to 80%. When the proportion of paraffin hydrocarbon exceeds the above range, the hydrocarbon plastic, particularly PS, becomes substantially insoluble. On the other hand, when the proportion is less than the above range, a substantial amount of the different hydrocarbon plastic, especially PVC is substantially dissolved. Will be dissolved. The proportion of the olefinic hydrocarbon in the mixture is the remaining amount obtained by subtracting the aromatic hydrocarbon and the paraffinic hydrocarbon in the mixture, and is usually 0 to 25%.

In the present specification, the proportions of the aromatic hydrocarbon, paraffinic hydrocarbon and olefinic hydrocarbon with respect to the fractionation solvent are different from the usual weight%,
It was determined based on a ¹³ C-NMR spectrum,
The apparatus for measuring the ¹³ C-NMR spectrum, the measurement conditions, the assignment of the spectrum, and the method for obtaining the ratio of each component are as follows.

(1) Apparatus The nuclear magnetic resonance spectroscopy (hereinafter referred to as NMR) apparatus used for the measurement is a GX270-FTNMR apparatus manufactured by JEOL Ltd. (2) Measurement conditions The sample was deuterated chloroform (CDCl ₃ : 99.96a manufactured by ISOTECINC.) As a solvent and an NMR lock agent.
dissolved in tom% D), 3 with respect to ¹³ C-NMR measurement
The concentration was 0 wt%. Chemical shift is 5 mmφ using tetramethylsilane (TMS) as an internal standard (0.0 ppm).
The measurement was performed at a rotation speed of 15 Hz using a Pyrex sample tube. The main measurement conditions are ¹³ C-NMR, ¹ H decoupling measurement with gate (NNE) eliminating nuclear Overhauser effect (NOE) for quantitative measurement.
Was performed, and the pulse repetition time was 6.9 seconds, the data point was 32 K, and the number of integrations was 4000. (3) Attribution of spectrum and determination of percentage of each hydrocarbon component ¹³ C-NMR spectrum is shown in Eberhand, Breifmaier., An
d Wolfgang Voelter. “Carbon-13 NMR Spectroscop
y ”, VCH Verlagsgesellschaft mbH, (1987) based on the attribution, calculated the integral value of each, and bond type carbon (paraffin hydrocarbon: Cp, olefin hydrocarbon: Co, aromatic carbon) The percentage of hydrogen: Ca) was determined Chemical shift of paraffinic hydrocarbon (Cp): 14.2
46.2 ppm Chemical shift of olefinic hydrocarbon (Co): 111.
5-114.2 ppm, 137.0-145.0 ppm Chemical shift of aromatic hydrocarbon (Ca): 125.5-
136.9 ppm In the method of calculating the percentage of each hydrocarbon component based on the ¹³ C-NMR spectrum, the aromatic hydrocarbon having a paraffinic hydrocarbon group bonded thereto is composed of a paraffinic hydrocarbon and an aromatic hydrocarbon. The aromatic hydrocarbon to which the olefinic hydrocarbon group is bonded is calculated by dividing into an olefinic hydrocarbon and an aromatic hydrocarbon.

Next, the present invention will be described with reference to the drawings. FIG. 1 shows an example of a flow sheet for implementing the method of the present invention. In this figure, 1 is a dissolution step, 2 is a solid-liquid separation step, 3 is a decomposition step, and 4 is a fractionation solvent fractionation step. In FIG. 1, the plastic waste is introduced into a dissolving step 1 through a line 5, where it is contacted with a fraction for a fractionating solvent which is circulated through a line 13 and subjected to a dissolving treatment. In this melting step 1, only the hydrocarbon-based plastic contained in the plastic waste is selectively melted, and the different hydrocarbon-based plastic is not substantially dissolved and is maintained in a solid state. The fraction for the fractionating solvent circulated to the dissolution step 1 through the line 13 is a liquid hydrocarbon mixture containing an aromatic hydrocarbon and a paraffin hydrocarbon. This fraction usually has a component composition suitable for the fractionating solvent shown above and exhibits an action of selectively solubilizing only the hydrocarbon-based plastic in the plastic waste. When the component composition of the plastic waste used as the raw material to be treated changes, the component composition of the circulating distillate also changes accordingly. Therefore, the component composition of this circulating distillate may deviate from the above-mentioned component composition range suitable for the fractionation solvent. In such a case, a suitable carbonization is performed so that the component composition becomes suitable for the fractionation solvent. Line 14 for hydrogen component
Add through. Generally, a product oil obtained by thermally decomposing a hydrocarbon plastic having an aromatic plastic content of 10 to 90% by weight, preferably 15 to 80% by weight, is obtained as it is or is obtained from this decomposition product oil. , 50
Fractions having a boiling point of ˜500 ° C., preferably 100 to 400 ° C. can be used as the fractionating solvent according to the invention. At the start of the dissolution operation in the dissolution step, an aromatic hydrocarbon commercially available as an industrial chemical, a paraffinic hydrocarbon and optionally an olefinic hydrocarbon are mixed in an appropriate amount, or a petroleum-based oil having the above-mentioned characteristics. Pyrolysis oil of hydrocarbon can be used as a fractionating solvent. In the melting step, the operating temperature is a temperature at which the hydrocarbon-based plastic is solubilized, and usually heating conditions are adopted, and it is generally 50 to 200 ° C, preferably 80 to 180 ° C. The operating pressure may be a pressure sufficient to keep the fractionated solvent in the liquid phase under the heating conditions, and is usually 0 to 5 kg / cm ² G, preferably 0 to 2
kg / cm ² G. The contact time is the time required for the hydrocarbon-based plastic to dissolve, and is usually 5 minutes or longer, preferably 10 to 60 minutes. The use ratio of the separating solvent is 0.5 to 10 per 1 part by weight of the plastic waste.
It is preferable to use a ratio of 1 part by weight, preferably 1 to 5 parts by weight. The plastic waste, prior to its melting process,
It is preferable to remove filth adhering to the surface or crush appropriately. Thereby, a smooth dissolution process can be performed.

The dissolution product obtained in the dissolution step 1 is sent to a solid-liquid separation step 2 through a line 6 and is subjected to solid-liquid separation there. As the solid-liquid separation method, various conventionally known methods, for example, filtration separation, centrifugation, sedimentation separation and the like are adopted. The operating temperature in this case is generally 50 to 20.
The temperature is 0 ° C., preferably 80 to 180 ° C., but is usually a temperature near the melting temperature in the melting step. In this solid-liquid separation step, a separation solvent solution in which the hydrocarbon plastic is dissolved and a solid different hydrocarbon plastic are obtained. The concentration of the hydrocarbon plastic in the fractionated solvent solution is 7 to 50% by weight, preferably 10 to 40% by weight. The concentration of this hydrocarbon-based plastic can be adjusted by the amount of the fractionation solvent used in the dissolution step.

The hydrocarbon solvent fractionating solvent solution obtained as described above is sent through line 7 to cracking step 3 where it is cracked and cracked product oil is obtained. As the decomposition method in this case, various conventionally known methods can be adopted. Generally, the decomposition temperature is 350-500 ° C, preferably 380-450 ° C. On the other hand, the solid different hydrocarbon-based plastic obtained in the solid-liquid separation step is discharged through the line 11,
It can be mixed with burned coal, wood powder, paper, fiber, etc. and made into solid fuel for reuse.

The cracked product oil obtained in the cracking step 3 is sent through a line 8 to a fractionating solvent fraction collecting step 4, where the fractionating solvent fraction used in the dissolving step 1 is fractionated.
A part of the fraction separated from this cracked oil is circulated to the dissolution step 1 through the lines 9 and 13, and the rest is discharged through the line 12. The fraction after the fractionation solvent fraction is collected is discharged through the line 10.
The fraction separated from the cracked product oil for the fractionating solvent is 50 to 500 ° C., preferably 150 to 4 contained in the cracked product oil.
It is a fraction having a boiling point of 00 ° C. The fractionation step 4 for the fractionating solvent is usually composed of one or a plurality of distillation columns. This fractionation solvent fractionation step 4 can be carried out in various forms. For example, the boiling point is higher than 500 ° C. from the cracked product oil obtained in the cracking step 3,
Preferably, the heavy oil fraction having a temperature higher than 400 ° C. is removed, and the obtained light oil fraction can be used as it is as a fractionating solvent fraction, and the light oil fraction is further distilled to have a boiling point of 100. It can be used as a fraction for a fractionating solvent except for a light fraction lower than ℃. Further, the cracked oil can be subjected to a distillation treatment to be divided into a plurality of fractions including a fraction for a fractionating solvent. The decomposition product oil obtained in the decomposition step 3 is 50 to 50.
It may have a boiling point of 0 ° C. In such a case,
It is also possible to circulate a part of the decomposition product oil as it is as a fractionating solvent.

[0014]

Next, the present invention will be described in more detail with reference to examples.

Reference Example 1 As a plastic waste model, PE: 35% by weight,
A plastic mixture consisting of 30% by weight of PP, 20% by weight of PS, 5% by weight of PVC, 5% by weight of PET and 5% by weight of ABS resin was crushed into strips. Next, Table 1
10 g of the crushed material was added to 100 g of each of the various solvents shown in (1) and heated at 130 ° C. for 30 minutes with stirring to conduct a plastic dissolution test. Table 2 shows the results. In Table 2, when the plastic component was dissolved in the solvent, it was indicated by "O", and when it was not dissolved, it was indicated by "X".

The specific contents of the pyrolysis oil shown in Table 1 are as follows. Pyrolysis oil A: Pyrolysis oil of PE Pyrolysis oil B: Mixed oil of pyrolysis oil of PS and pyrolysis oil of PE (mixing weight ratio = 0.95 / 0.05) Pyrolysis oil C: PE Mixed oil of pyrolyzed oil, pyrolyzed oil of PP and pyrolyzed oil of PS (mixing weight ratio = 1/1/1) Pyrolyzed oil D: Fraction of boiling point of pyrolyzed oil of PE below 280 ° C Oil E: a fraction having a boiling point of 150 to 350 ° C. of pyrolysis oil C Pyrolysis oil F: a fraction having a boiling point of 280 ° C. or lower of pyrolysis oil C Pyrolysis oil G: A fraction having a boiling point of 280 ° C. or lower of pyrolysis oil of PE Oil of a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PP and a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PS (mixing weight ratio = 8/8/84) A mixed oil of a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil, a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PP, and a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PS (Weight ratio = 44/45/11)

[0017]

[Table 1]

[0018]

[Table 2]

Reference Example 2 Hydrocarbon-based plastic mixture (PE: 41% by weight, PP: 35) of the plastic mixture shown in Reference Example 1.
%, PS: 24% by weight) 20 g was dissolved in 100 g of the solvent F to give a solution, and this solution was added to 400
Pyrolysis was performed under conditions of a temperature of ℃ and normal pressure to obtain a decomposition product oil. Next, this cracked oil is distilled to a boiling point of 100-
A fraction A having a temperature of 400 ° C. was obtained. Next, a dissolution test of the plastic mixture was performed in the same manner as in Reference Example 1 except that this fraction A was used as a fractionating solvent. As a result, it was confirmed that PE, PP and PS were all dissolved. Also, PV
It was confirmed that the C, PET and ABS resins were all substantially insoluble and retained solid in the solvent.
The ratio of aromatic hydrocarbons, paraffinic hydrocarbons and olefinic hydrocarbons contained in the fraction A is ¹³ C.
-When investigated based on the spectrum of NMR, the results of aromatic hydrocarbon: 35%, paraffinic hydrocarbon: 50% and olefinic hydrocarbon: 15% were obtained.

Example 1 The crushed product of the plastic mixture shown as the plastic waste model in Reference Example 1 was treated according to the flow sheet shown in FIG. (1) Dissolution step Fraction A shown in Reference Example 2 was used as a fractionating solvent, 100 parts by weight of the plastic mixture was added to 300 parts by weight of this fraction A, and the temperature was 130 ° C. and normal pressure was applied for 30 minutes. Hold and selectively dissolve only the hydrocarbon-based plastic in the plastic mixture. (2) Solid-Liquid Separation Step The dissolution product obtained in the dissolution step is subjected to solid-liquid separation by filtration at a temperature of 130 ° C., and 375 parts by weight of a solution containing a hydrocarbon plastic at a concentration of 20% by weight, and solid foreign carbonization. 25 parts by weight of hydrogen-based plastic was obtained. (3) Decomposition step 100 parts by weight of the solution containing the hydrocarbon-based plastic obtained in the solid-liquid separation step is heated at a temperature of 400 ° C. and atmospheric pressure for 30 times.
After thermal decomposition treatment for 98 minutes, 98 parts by weight of decomposition product oil was obtained. (4) Fraction fractionation step for fractionation solvent The cracked oil obtained in the cracking step is distilled to a boiling point of 400 ° C.
The above heavy oil fraction was separated into 0.7 parts by weight and a light oil fraction having a boiling point of 150 ° C. or lower 5.4 parts by weight. The light oil fraction thus obtained was subjected to a composition analysis based on the spectrum of ¹³ C-NMR, and as a result, aromatic hydrocarbons: 35%, paraffinic hydrocarbons: 50% and olefinic hydrocarbons: It consisted of 15%. Using this light oil fraction as a fractionating solvent, the result of the dissolution treatment of the plastic mixture in the same manner as the dissolution step,
It was confirmed that all the hydrocarbon-based plastics were dissolved, but none of the different hydrocarbon-based plastics were dissolved, and that they were held in a solid state.

[0021]

In the method for treating plastic waste of the present invention, the different hydrocarbon plastic contained in the plastic waste is removed from the plastic waste by way of the dissolving step and the solid-liquid separation step. It is not introduced into the decomposition process. Therefore, in the case of the present invention, problems such as corrosion and clogging of the device caused by decomposition products of different hydrocarbon plastics and generation of toxic gas do not occur at all. Moreover, in the case of the present invention, the fraction fractionated from the cracked product oil can be used as it is as the fractionating solvent in the dissolving step, so that the process efficiency is very high.

[Brief description of the drawings]

FIG. 1 shows an example of a flow sheet for carrying out the method of the present invention.

[Explanation of symbols]

 1 Dissolution process 2 Solid-liquid separation process 3 Decomposition process 4 Fractional solvent fractionation process

Claims (6)

[Claims] 1. A method of treating a plastic waste consisting of a hydrocarbon plastic and a different hydrocarbon plastic, comprising the steps of: (i) dissolving the hydrocarbon plastic into the waste, but substantially eliminating the different hydrocarbon plastic. A dissolution step of bringing only a hydrocarbon-based plastic contained in the waste into contact with a separation solvent that does not dissolve to selectively dissolve, and (ii) a dissolution product obtained in the dissolution step A separation solvent solution in which is dissolved, and a solid-liquid separation step of separating into a solid different hydrocarbon plastic, (iii) by decomposing the separation solvent solution of the hydrocarbon plastic obtained in the solid-liquid separation step, And a part of the decomposition product oil obtained in the decomposition step is used as at least part of the fractionating solvent in the dissolution step. And processing method of the plastic waste 該分 another solvent, characterized in that it consists of a liquid hydrocarbon mixture containing aromatic hydrocarbons and paraffinic hydrocarbons. 2. The decomposition product obtained in the decomposition step is introduced into a fractionation solvent fractionation step to fractionate a fractionation solvent fraction, and a part of this fraction is used as at least a part of the fractionation solvent. The method of claim 1. 3. The method according to claim 1, wherein the hydrocarbon-based plastic comprises at least one plastic selected from polyolefin-based plastics and aromatic-based plastics. 4. The method according to claim 1, wherein the different hydrocarbon-based plastic comprises at least one plastic selected from polyvinyl chloride, polyethylene terephthalate and ABS resin. 5. The method according to claim 1, wherein the proportion of the aromatic plastic contained in the hydrocarbon plastic is 10 to 90% by weight. 6. The fractionation solvent has a proportion of aromatic hydrocarbons of 5 to 70% and a proportion of paraffinic hydrocarbons of 5 to 85.
%, The method according to any one of claims 1 to 4.