JP2000248110A - Method for dehalogenating organic halogen-containing plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dehalogenate an organic halogen-containing plastic at good efficiency by removing the plasticizer from the plastic by extraction with an organic solvent, mixing the plasticizer-free residue with a metal oxide and/or a metal hydroxide, and mechanochemically treating the mixture. SOLUTION: A plastic is broken to a size of about 5 mm or below with a cutter or shredder, and the cut pieces are immersed in an organic solvent under agitation. The solvent containing the plasticizer is separated by filtration. The plasticizer-free residue is mixed with a metal oxide and/or a metal hydroxide, and the mixture is ground with e.g. a ball mill. The treated product is withdrawn and subjected to a treatment for eluting chlorine for 1-2 hr under agitation in an at least about 10-fold amount of water and filtered and dehydrated to accomplish dechlorination. The metal oxide and/or metal hydroxide used are desirably oxides and/or hydroxides of calcium and/or strontium and are desirably used in an amount at least twice the reaction molar equivalents of the halogen atoms contained in the material to be dehalogenated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dehalogenating an organic halogen-containing plastic which generates a harmful gas when a polyvinyl chloride resin, a fluororesin or the like is burned.

[0002]

2. Description of the Related Art Polyvinyl chloride resin has heat resistance, corrosion resistance,
Because of its excellent moldability, it is widely used in various fields. Therefore, the amount of polyvinyl chloride to be discarded is increasing year by year, and it is incinerated with other garbage as it is, and the generation of harmful gas from the incineration facility has become a social problem.

As a test, 250 to 30 dechlorination treatments are used.
It is decomposed by heating to 0 ° C and chlorine is recovered as hydrochloric acid.
Due to the high temperature treatment, it has not been widely used due to the safety of the processing equipment.

[0004] Fluororesins such as polyfluorinated ethylene are excellent in heat resistance and chemical resistance and are used as materials for valves and linings. However, there is a problem that toxic gases such as hydrogen fluoride are generated by incineration. is there.

[0005] As described above, plastics containing an organic halogen compound have high chemical stability and various good properties.
Although it is used in various fields, it is difficult to treat because of its chemical stability, and at present it is difficult to treat.

[0006]

As described above, Cl.F.
Removal is a problem, and attention was paid to mechanochemical treatment as a method for removing Cl and F.

[0007] The mechanochemical treatment is a treatment in which a reaction product is pulverized by an impact pulverizer such as a ball mill. The milling physically tears off the reactants at the molecular level, creating a highly active molecular surface. This allows a reaction that cannot take place at normal temperature to proceed.

Incidentally, organic halogen-containing plastics such as polyvinyl chloride are sometimes used as they are.
Many products use about 0% of a plasticizer kneaded. By improving the deformability with this plasticizer, many uses are created, such as agricultural sheets, boots, hoses, and wire covering materials.

However, there is a problem that the presence of the plasticizer hinders the pulverization by a ball mill or the like, and significantly reduces the reaction efficiency of the mechanochemical treatment.

An object of the present invention is to provide a method for dehalogenating an organic halogen-containing plastic in which a plasticizer present in the organic halogen-containing plastic is separated in advance and a mechanochemical treatment is efficiently performed.

[0011]

Means for Solving the Problems The present inventors have obtained the following findings as a result of repeated tests. (1) When the plasticizer in the organic halogen-containing plastic is extracted and removed with an organic solvent, the remaining plastic becomes porous.

(2) Because of the porous plastic,
It is easy to pulverize with a ball mill or the like, and the dechlorination efficiency during mechanochemical treatment is improved.

The present invention has been made based on the above findings, and the gist thereof is as follows.

After extracting and removing the plasticizer kneaded into the organic halogen-containing plastic using an organic solvent,
A method for dehalogenating organic halogen-containing plastics, comprising mixing an organic halogen-containing plastic from which a plasticizer has been removed with an oxide and / or a hydroxide and performing a mechanochemical treatment.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for extracting and removing a plasticizer kneaded in an organic halogen-containing plastic by using an organic solvent is as follows.

The plastic is crushed to about 5 mm or less using a cutter or a shredder, immersed in an organic solvent and stirred. Thereafter, the solvent containing the plasticizer is separated using a filter, and the plasticizer can be extracted and removed.

The organic solvent used for removing the plasticizer may be any organic solvent such as acetone, toluene, diethyl ether and kerosene, and is not particularly limited.

The residue from which the plasticizer has been removed and the metal oxide and / or hydroxide are mixed and ground with a ball mill or the like. The material of the crushing container and the crushing ball is not particularly limited, but stainless steel, tungsten carbide, agate and the like are preferable.

After the completion of the mixing and pulverization, the mixed product is taken out and stirred in water of about 10 times or more by weight while stirring.
A process for eluting chlorine is performed for a period of time, followed by filtration and dehydration to complete the dechlorination process.

The oxides and hydroxides to be added and mixed are preferably calcium and / or strontium oxides and hydroxides.

The total content of strontium and calcium requires at least the halogen content of the treated product and the reaction molar equivalent (hereinafter, also simply referred to as the reaction equivalent), and is preferably at least twice the reaction equivalent. Even in the case of an equivalent, the removal of halogen is possible, but the removal rate is limited to 70 to 80%, and a removal rate of 90% is obtained at about twice the reaction equivalent. It requires 3 to 5 times the equivalent amount.

The removal rate can be increased in a short time as the amount of addition increases, but when added 10 times or more the reaction equivalent, the halogen concentration in the whole reaction system decreases, and the removal rate tends to decrease.

[0023]

(Comparative Example 1) 27 g of quicklime (CaO) was mixed with 10 g of a polyvinyl chloride product containing about 50% of dioctyl phthalate (DOP) as a plasticizer.
Perform a mechanochemical treatment in a ball mill for ~ 3 hours, take out the mixed sample, and stir in stirring water (500cc
Was washed with water, and the chlorine residue in the filtered residue was analyzed to determine the dechlorination rate. The added amount of quicklime (CaO) is equivalent to three times the reaction equivalent.

(Invention Example 1) A polyvinyl chloride sheet product (about 1.5 mm thick) containing about 50% of dioctyl phthalate (DOP) as a plasticizer used in Comparative Example 1 was cut into 5 × 5 mm or less. After a sample of 20 g was immersed in diethyl ether in a stainless steel container and allowed to stand at room temperature for about 2 hours, a solvent containing a plasticizer was filtered with a filter, and the residue was taken out and dried. 27 g of quicklime (CaO) was mixed with the sample from which the plasticizer had been removed, subjected to a mechanochemical treatment with a ball mill for 1 to 3 hours, and the mixed sample was taken out and washed with stirring water (500 cc capacity) for about 1 hour. Chlorine in the filtered residue was analyzed to determine the dechlorination rate. This quicklime (C
The amount of aO) added corresponds to three times the reaction equivalent.

Comparative Example 2 27 g of quicklime (CaO) was added to a 10 g sample of pure polyvinyl chloride containing no plasticizer.
Are mixed and subjected to a mechanochemical treatment in a ball mill for 1 to 3 hours, a mixed sample is taken out, washed for about 1 hour with stirring water (500 cc capacity), and the chlorine residue in the filtered residue is analyzed to determine the dechlorination rate. Was. The added amount of quicklime (CaO) is equivalent to three times the reaction equivalent.

Table 1 shows the values of the dechlorination rate (%) under the above conditions. As shown in Table 1, Example 1 of the present invention in which a mechanochemical treatment was performed after removing the plasticizer in advance.
Dechlorination rate (%) than Comparative Example 1 in which the plasticizer was not removed in advance, and Comparative Example 2 in which the plasticizer was not added.
Was high.

[0027]

[Table 1]

[0028]

According to the present invention, dehalogenation from an organic halogen-containing plastic can be efficiently performed by mechanochemical treatment.

Claims (1)

[Claims] After extracting and removing a plasticizer kneaded in an organic halogen-containing plastic using an organic solvent, the organic halogen-containing plastic from which the plasticizer has been removed is mixed with a metal oxide and / or a hydroxide. A method for dehalogenating an organic halogen-containing plastic, comprising performing a mechanochemical treatment.