JP2006045469A - Method for dehalogenating halogen-containing polymer with ammonia-containing aqueous solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently dehalogenating a halogen-containing polymer at a low cost. <P>SOLUTION: This method for dehalogenating a halogen-containing polymer is characterized by bringing the halogen-containing polymer into contact with an ammonia-containing aqueous solution heated at 180 to 350°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for dehalogenating a halogen-containing polymer with an aqueous ammonia-containing solution.

  Chlorinated polymers (resins) such as polyvinyl chloride and polyvinylidene chloride are excellent in chemical and mechanical properties and are widely used as industrial or consumer products. These chlorine-containing polymers have a production amount of about 10% or more of Japanese synthetic resin products, and are contained in large amounts in industrial waste and domestic waste. Incineration and landfilling are the main disposal methods for chlorine-containing polymers, but problems such as shortage of landfill and the elution of harmful plasticizers called so-called environmental hormones have been pointed out.

  On the other hand, many studies have been conducted on the thermal decomposition of polyvinyl chloride. In a nitrogen atmosphere, side chain dechlorination proceeds at a decomposition temperature of about 300 ° C., and main chain decomposition occurs at 350 ° C. or higher. It is known that a naphthalene-based compound is produced at 600 ° C. or higher (for example, see Non-Patent Document 1). Therefore, there is a possibility that harmful substances such as hydrogen chloride gas and dioxin may be discharged during incineration, and hydrogen chloride contained in the combustion gas causes corrosion of the furnace material, which requires exhaust gas treatment.

  In order to solve such a problem, it is considered to dechlorinate by pretreating a chlorine-containing polymer. For example, supercritical water or supercritical water oxidation treatment (for example, see Non-Patent Document 1). ), Hydrothermal treatment, and mechanochemical methods. However, since supercritical water treatment is performed under conditions of a critical temperature of 374 ° C. or higher and a critical pressure of 22.06 MPa or higher, the carbon skeleton chain of polyvinyl chloride is cleaved by high-temperature treatment to generate a low molecular organic halogen compound. In addition, the construction cost is high because of the use of a high-temperature and high-pressure device, and maintenance is not easy. Also, the corrosion of the reaction apparatus is severe, and in order to suppress this, the structure of the apparatus becomes complicated, such as a double structure inside the apparatus or a temperature gradient. In the mechanochemical method, dechlorination is performed by contacting calcium oxide or calcium carbonate particles with chlorine-containing resin particles. However, the sample must be pulverized in order to achieve good contact with the target sample.

Further, in the hydrothermal treatment, dechlorination proceeds in the form of hydrogen chloride, and it condenses with water vapor to produce hydrochloric acid, which causes a problem of corrosion of the reactor. In order to prevent this, a method in which a strong alkaline aqueous solution such as sodium hydroxide or potassium hydroxide is allowed to act on the decomposition product gas to neutralize it (for example, see Non-Patent Document 2), or ammonia is allowed to act on the decomposition product gas. A method for recovering ammonium chloride (for example, see Patent Document 1 or 2) has been developed. However, when a strong alkali is added, the alkali concentration of the added base is as high as several percent or more, which causes alkali corrosion of the reactor. Further, the method described in Patent Document 1 requires heating to 350 ° C. or higher for thermal decomposition.
JP-A 52-53979 JP 2000-104075 A Kiyoji Saito, “Decomposition of Polyvinyl Chloride in High Temperature and High Pressure Water”, Polymer Processing, 2001, Vol. 50, No. 10, p. 434-438 Nobuaki Shin, Toshiaki Yoshioka, Shogo Okwaki, “Decomposition behavior of high-temperature aqueous solution of polyvinyl chloride film for agriculture and characteristics of generated carbon”, Journal of Waste Science, 1998, Vol. 9, No. 4, p. 141-148

  An object of the present invention is to provide a method for efficiently dehalogenating a halogen-containing polymer at a low cost.

  As a result of intensive studies, the present inventors have found that ammonia is superior in permeability or permeability into halogen-containing polymers as compared with other alkali compounds and has a high dehalogenation rate. Furthermore, the present inventors contact the halogen-containing polymer with an ammonia-containing aqueous solution heated to 180 ° C. or more and less than 350 ° C., so that the halogen-containing polymer does not undergo severe thermal decomposition that involves breaking of the carbon skeleton chain. It was found that can be efficiently dehalogenated. The present invention has been made based on such knowledge.

That is, the present invention
(1) A method for dehalogenating a halogen-containing polymer, comprising contacting an ammonia-containing aqueous solution heated to 180 ° C. or more and less than 350 ° C. with the halogen-containing polymer,
(2) The method for dehalogenating a halogen-containing polymer as described in (1) above, wherein the concentration of the ammonia-containing aqueous solution is 0.006 to 10 mol / l, and (3) the halogen-containing polymer The present invention provides a method for dehalogenating a halogen-containing polymer as described in (1) or (2), wherein is a polyvinyl chloride or polyvinylidene chloride.
In the present invention, the halogen-containing polymer means a polymer compound containing halogen and a resin composition containing halogen. Here, the containing form of the halogen atom is not limited, and may be any of those bonded to the polymer as constituent atoms, those doped, and those mixed as other additives. The polymer may be solid or melted.

According to the method of the present invention, an aqueous solution containing ammonia heated to 180 ° C. or more and less than 350 ° C. is brought into contact with the halogen-containing polymer, so that the halogen-containing high concentration can be obtained without violent thermal decomposition such as breaking the carbon skeleton chain. Molecules can be efficiently dehalogenated. Since the ammonia-containing aqueous solution is excellent in resin permeability, it is not necessary to pulverize the resin sample and make fine particles, and it is possible to efficiently dehalogenate samples having various shapes.
In addition, according to the present invention, it can be efficiently dehalogenated using a low-concentration ammonia-containing aqueous solution, so that the amount of ammonia used may be small, and human waste treatment, livestock waste treatment, sewage treatment, Ammonia generated in the methane fermentation process and its pretreatment process in various organic waste treatments such as sewage sludge treatment and garbage treatment can be used, which is excellent in terms of cost. In recent years, there has been a problem with disposal of ammonia generated from a sewage treatment plant or the like. By using this ammonia in the present invention, such a problem can also be solved.

Hereinafter, the present invention will be described in detail.
The halogen-containing polymer dehalogenation method of the present invention is characterized in that an ammonia-containing aqueous solution heated to 180 ° C. or more and less than 350 ° C. is brought into contact with the halogen-containing polymer.
Alkaline agents such as sodium hydroxide, potassium hydroxide, and ammonia are used in conventional hydrothermal treatment methods. This is intended to neutralize halogen gas and hydrogen halide released from halogen-containing polymers. It is used in.
In the present invention, it is noted that ammonia is more permeable or permeable to halogen-containing polymers than other alkali compounds, and has a high dehalogenation rate. An ammonia-containing aqueous solution is used for the purpose of causing a chemical reaction. Since the ammonia-containing aqueous solution is excellent in resin permeability, it is not necessary to pulverize the resin sample and make fine particles, and it is possible to efficiently dehalogenate samples having various shapes. Further, since the aqueous ammonia-containing solution is basic, it is useful for neutralization of a dehalogenation reaction product (for example, hydrochloric acid).

  In the present invention, the ammonia-containing aqueous solution refers to an aqueous ammonia solution and an aqueous solution of an ammonium salt. Examples of the ammonium salt include weak acid salts of ammonia such as ammonium carbonate, ammonium hydrogen carbonate, ammonium carbamate, ammonium acetate, and ammonium phosphate. The strong acid salt of ammonia is acidic in its aqueous solution, so the dehalogenation effect is small compared to an aqueous ammonia solution or a weak acid salt solution of the same concentration. In the present invention, it is particularly preferable to use an aqueous ammonia solution.

The concentration of the aqueous ammonia-containing solution used in the present invention is preferably 0.006 to 10 mol / l, and more preferably 0.6 to 6 mol / l. The higher the concentration of the ammonia-containing aqueous solution, the higher the dehalogenation rate. However, if the concentration is too high, the reactor may be corroded.
In the present invention, it is possible to dehalogenate sufficiently efficiently with a low-concentration aqueous solution containing ammonia, so that the amount of ammonia used may be small, and human waste treatment, livestock waste treatment, sewage treatment, sewage sludge treatment, Ammonia generated in the methane fermentation process and its pretreatment process in various organic waste treatment such as garbage treatment can be used.

In the present invention, the ammonia-containing aqueous solution is heated to 180 ° C. or higher and lower than 350 ° C., preferably 200 to 250 ° C. Conventionally, the dehalogenation reaction in a nitrogen atmosphere has been performed at about 300 ° C. or higher, and severe thermal decomposition accompanied by cleavage of the carbon skeleton chain of the halogen-containing polymer occurs at 350 ° C. or higher. In the present invention, since the treatment is performed at a low temperature, no severe thermal decomposition accompanied by the cleavage of the carbon skeleton chain of the halogen-containing polymer occurs. Further, since the present invention performs the dehalogenation reaction at a lower temperature than the conventional method, the processing pressure can be reduced by lowering the processing temperature, and the corrosion of the reactor can be drastically reduced. In particular, when the treatment temperature is about 200 ° C., the treatment can be sufficiently performed in a Teflon-lined reactor, so that the cost of the apparatus can be reduced.
In the present invention, the ammonia-containing aqueous solution heated to 180 ° C. or higher and lower than 350 ° C. includes not only a liquid state but also a gaseous state. Therefore, contacting the halogen-containing polymer with an ammonia-containing vapor at 180 ° C. or higher and lower than 350 ° C. is also included in the scope of the present invention.

As the reaction apparatus, any of a batch reactor, a semi-batch reactor, or a flow reactor may be used, but a batch or semi-batch reactor is preferably used, and a semi-batch reactor is used. It is more preferable to carry out using. When a semi-batch reactor is used, a halogen-containing polymer sample is placed in the reactor and an aqueous ammonia-containing solution is circulated. In the case of a flow reactor, a halogen-containing polymer sample and an ammonia-containing aqueous solution are simultaneously introduced into the reactor so that a dehalogenation reaction can be performed continuously. For this, operations such as uniformizing the size of the sample and pulverization are required.
In a batch or semi-batch reactor, the ammonia-containing aqueous solution in the sealed reactor is pressurized with heating, but may be further pressurized from the outside using a pump. However, the upper limit of pressurization is not particularly limited, but is preferably lower considering the cost of the apparatus.
The ammonia-containing aqueous solution used in the present invention is preferably heated to 180 to 350 ° C. and pressurized to 1 to 50 MPa, more preferably 200 to 250 ° C. and pressurized to 5 to 15 MPa. .

  In the present invention, as the dehalogenation reaction proceeds, the pH of the reaction solution is lowered by a reaction product such as hydrochloric acid. Therefore, in consideration of neutralization of the reaction solution, the ammonia-containing aqueous solution is preferably used in an amount of ammonia equal to or greater than the amount of halogen contained. In particular, when a batch reactor is used, in order to prevent corrosion of the reactor, it is desirable to use an ammonia amount equimolar to the halogen content.

The halogen-containing polymer compound to which the present invention is applied is preferably a chlorine-containing polymer, a bromine-containing polymer, or an iodine-containing polymer, more preferably a chlorine-containing polymer or a bromine-containing polymer, Particularly preferred is a chlorine-containing polymer. Specifically, examples of the chlorine-containing polymer include polyvinyl chloride, polyvinylidene chloride, and polychloroprene, and examples of the bromine-containing polymer include polyvinyl bromide and polybromoxylylene. The present invention can also be applied to a conductive polymer obtained by doping a polyacetylene, polythienopyrazine, polyferrocenylene silylene, or the like with a halogen element (for example, iodine). In particular, the present invention can be suitably applied to commonly used polyvinyl chloride or polyvinylidene chloride.
Examples of the halogen-containing resin composition to which the present invention is applied include resins containing flame retardants such as decabromodiphenyl ether, polybrominated diphenyl ether, and polybrominated naphthalene.
Since the ammonia-containing aqueous solution is excellent in resin permeability, it is not necessary to pulverize the resin sample and make it fine particles. Therefore, the halogen-containing polymer to be treated may have any shape and may be a molten liquid.

The operation procedure of the method of the present invention will be described by taking a case of using a batch reactor as an example. First, a halogen-containing polymer sample is placed in a reaction vessel, an aqueous ammonia-containing solution is introduced from a solvent introduction port of the reaction vessel, and the reaction vessel is sealed. The reaction vessel is heated so that the ammonia-containing aqueous solution in the reaction vessel is 180 ° C. or higher and lower than 350 ° C., and the dehalogenation reaction is performed under a predetermined temperature condition. The reaction time depends on the temperature and concentration of the ammonia-containing aqueous solution. When a semi-batch reactor is used, it further depends on the flow rate of the ammonia-containing aqueous solution, but is preferably 5 to 120 minutes, more preferably 20 to 60 minutes.
After a predetermined time has elapsed, the container is opened and returned to normal pressure, the reaction solution is discharged from the solvent outlet of the reaction vessel, and this is cooled and condensed to be recovered. The collected solution is tested, and when harmful substances are detected, they are detoxified by any method. For example, when an endocrine disrupting substance is detected, it can be completely oxidatively decomposed by subcritical water oxidation treatment. On the other hand, the solid residue after the treatment is recovered after cooling the reaction vessel. Since the solid residue after the dehalogenation reaction is mainly composed of carbon and hydrogen, it can be incinerated and used as a heat source, and can also be used as a raw material such as activated carbon.

Specifically, the present invention can be used for the following applications, for example.
(1) Treatment of used medical devices (such as syringes) Since the present invention is treated at a high temperature of 180 ° C. or higher and lower than 350 ° C. and does not require pulverization of the sample, medical devices such as used syringes are washed and sterilized as they are. It is safe because it can be processed without any changes. In addition, since almost no gas product is generated, it can be treated entirely in a closed system, and all the waste liquid can be collected, analyzed and discarded. When there is a possibility of contamination by harmful proteins or pathogens, organic matter in the wastewater is completely oxidatively decomposed through a process such as subcritical water oxidation with an oxidizing agent such as oxygen or hydrogen peroxide. it can.

(2) Detoxification and resource recycling of wire covering materials Wire covering materials are produced and discarded in large quantities, but plasticizers are used to make wire covering materials flexible and flame retardant. And various additives such as flame retardants, and when discarded, these additives are eluted as endocrine disrupting substances (so-called environmental hormones) and have an effect on the environment. Since the method of the present invention is a closed system treatment, it can be recovered as a solid residue and waste liquid after the treatment, and further, a subcritical hydroxylation treatment is performed to completely oxidize and detoxify the endocrine disrupting substance. Is possible. Since the solid residue is mainly composed of carbon and hydrogen, it can be incinerated to be a heat source, and can also be a raw material such as activated carbon. In addition, it is not necessary to separate the synthetic resin such as fibers contained in the coating material, paper, rubber, etc., and these can hardly be decomposed at the processing temperature in the present invention or can be classified mechanically because the decomposition speed is slow. .

(3) Water pipes and sewage pipes Since the processing of hard vinyl chloride used in water pipes and sewage pipes has various shapes and sizes, conventionally, energy required for miniaturization such as pulverization has been large. However, according to the present invention, there is no need for miniaturization or less.
(4) Agricultural vinyl chloride Agricultural vinyl chloride resin used in greenhouses and disposed of in large quantities every year is soiled with soil. However, according to the present invention, the cleaning step is almost unnecessary and the processing can be performed as it is.

(5) Treatment of building materials such as wallpaper Since the wallpaper is made of vinyl chloride resin with synthetic glue or paper, it has been extremely difficult to treat. However, according to the present invention, a laminated sample made of paper, synthetic resin, or the like can be processed as it is, and at the processing temperature in the present invention, these polymer materials are hardly decomposed or the decomposition rate is slow, so that the machine Can be classified.
(6) Food packaging wraps Food packaging wraps used in supermarkets and the like use a lot of chlorine-containing polymer materials such as polyvinylidene chloride, and meat juices, vegetable juices, and the like adhere to them. According to the present invention, the cleaning process is almost unnecessary, and can be processed as it is.

  Hereinafter, the present invention will be described in more detail based on examples, but is not limited thereto.

Example 1
A semi-batch reactor was used as the reactor. Commercially available granular polyvinyl chloride (trade name: Vinyl
Chloride Polymer (manufactured by Kanto Chemical Co., Inc., 100% polyvinyl chloride, molecular weight 62500) is placed in a reaction vessel, and a 0.6 mol / l aqueous ammonia solution is flowed at a flow rate of 3 ml using a syringe pump (100DM, trade name, manufactured by ISCO). / Min (standard state) continuously fed to the reactor. At the same time that the aqueous ammonia solution was started to be fed to the reactor, the reactor was immersed in a molten salt bath maintained at 240 ° C. The reaction time measurement was started from the time when the reactor was immersed in the molten salt bath. When the temperature in the reactor was measured using a thermocouple, it reached 240 ° C. within 1.5 minutes. After reacting for a predetermined time at a reaction temperature of 240 ° C., the reaction solution was recovered and the dechlorination rate was measured. The measurement of the dechlorination rate was performed by measuring the chloride ion concentration using an ion chromatograph (DX-120, manufactured by Nippon Dionex; separation column Ion Pax AS12A, each trade name).
As a comparative example, in place of the aqueous ammonia solution described above, a test was conducted in the same manner with respect to a sample introduced with a 1 mol / l sodium hydroxide aqueous solution and a sample introduced with distilled water.

The measurement results are shown in FIG. FIG. 1 is a graph showing the change over time in the dechlorination rate. The vertical axis represents the dechlorination rate (%), and the horizontal axis represents the reaction time (minutes).
As is clear from FIG. 1, when distilled water was compared with sodium hydroxide, it was found that sodium hydroxide was not very effective in improving the dechlorination rate. Sodium hydroxide is used as an additive in conventional hydrothermal treatment, but this is not the purpose of improving the dechlorination rate, but is added for the purpose of adjusting the pH drop accompanying the progress of the reaction. Recognize.
On the other hand, it was found that the aqueous ammonia solution drastically improves the dechlorination rate despite the lower concentration than the aqueous sodium hydroxide solution.

Example 2
Each of the aqueous ammonia solution, aqueous sodium hydroxide solution, and distilled water used in Example 1 was reacted in the same manner as in Example 1 except that the reaction temperature was changed. The reaction solution was recovered and the dechlorination rate constant was determined as follows. Since it can be assumed that the dechlorination rate can be approximated by the first-order reaction rate equation, the reaction rate is expressed by the following equation (1).
-DC / dt = kC (1)
In the formula, C is a chlorine concentration in the sample, k is a reaction rate constant, and t is time. Here, the chlorine concentration C in the sample was obtained from the difference between the chlorine concentration in the initial sample obtained by elemental analysis and the eluted chlorine ion concentration measured using an ion chromatograph in the same manner as in Example 1.
When this equation (1) is integrated, the following equation (2) is derived.
ln (C / C ₀ ) = − kt = −Aexp (−E / RT) t (2)
In the formula, C is the chlorine concentration in the sample at the reaction time t, C ₀ is the chlorine concentration in the first sample, A is the frequency factor, E is the activation energy, and R is the gas constant.
C / C ₀ was logarithmically plotted against the reaction time at each temperature, and the reaction rate constant was determined from the linear gradient (−k) obtained from the equation (2).

These results are shown in FIG. FIG. 2 is a graph showing an Arrhenius plot for the dechlorination rate constant at each temperature. The vertical axis represents the dechlorination rate constant k (1 / min), and the horizontal axis represents the reaction temperature 1000 / T (1 / K). ).
As is clear from FIG. 2, the dechlorination rate for the 0.6 mol / l aqueous ammonia solution is 35 to 40 times that for distilled water without addition and 15 to 20 times that for the 1 mol / l sodium hydroxide aqueous solution. I found it big. From this, it was found that the aqueous ammonia solution has a similar dechlorination effect in any temperature range.

Example 3
A batch reactor was used as the reactor. A 30 mg sample was placed in a room temperature reaction vessel (internal volume 3.6 ml), and 2 ml of an aqueous ammonia solution having a predetermined concentration was placed. The reaction vessel was sealed and immersed in a molten salt bath maintained at 220 ° C. The reaction time measurement was started from the time when the reactor was immersed in the molten salt bath. When the temperature inside the reactor was measured using a thermocouple, it reached 220 ° C. within 1.5 minutes. After carrying out the reaction at a reaction temperature of 220 ° C., the reaction vessel was taken out of the bath and quenched with water. The contents were taken out from the reaction vessel, filtered with distilled water, and the chlorine ion concentration in the filtrate was measured for the dechlorination rate using an ion chromatograph in the same manner as in Example 1.

The measurement results are shown in FIG. FIG. 3 is a graph showing the change over time in the dechlorination rate. The vertical axis represents the dechlorination rate (%), and the horizontal axis represents the reaction time (minutes).
As apparent from FIG. 3, it was found that the dechlorination rate was improved as the ammonia concentration was increased. When dechlorination rate constants were calculated for these, it was found that the dechlorination rate increased in proportion to approximately 0.5th power of the ammonia concentration in the aqueous ammonia solution.
In addition, when it reacted similarly using distilled water instead of ammonia aqueous solution, at this temperature, the dechlorination reaction hardly occurred within the time measured in the present Example.

Example 4
As an aqueous solution of another ammonium salt, an ammonium carbonate aqueous solution that is a weak acid salt (a mixture of ammonium hydrogen carbonate and ammonium carbamate, 30% as NH ₃ , manufactured by Kanto Chemical) 0.1 mol / l or an ammonium chloride aqueous solution that is a strong acid salt ( Kanto Chemical Co., Ltd., 99%) 0.1 mol / l was used, and the reaction temperature was 250 ° C., except that the reaction was carried out with an aqueous ammonia solution and distilled water, and the dechlorination rate was measured. .
The measurement results are shown in FIG. FIG. 4 is a graph showing the change over time in the dechlorination rate. The vertical axis represents the dechlorination rate (%), and the horizontal axis represents the reaction time (minutes).
As is clear from FIG. 4, the strong acid salt ammonium chloride aqueous solution also showed a dehalogenation effect, but the weak acid salt ammonium carbonate aqueous solution had a higher dechlorination effect.

Example 5
The vinyl hose is used as a representative product of a soft polyvinyl chloride material, polyvinyl chloride is used as a main component, and a lot of additives such as a plasticizer are contained in order to soften the vinyl hose.
A commercially available vinyl hose (trade name: Powered, manufactured by Sanyo Kasei Co., Ltd.) was used as a sample, and the reaction temperature and pressure were 220 ° C./2.3 MPa, 240 ° C./3.3 MPa, 260 ° C./4.7 MPa. Except for this, the reaction was carried out with respect to the aqueous ammonia solution and distilled water in the same manner as in Example 3. After a predetermined time had elapsed, the reaction solution was recovered and the dechlorination concentration was measured.

The measurement results are shown in FIG. FIG. 5 is a graph showing the change over time in the dechlorination concentration. The vertical axis represents the dechlorination concentration (ppm), and the horizontal axis represents the reaction time (minutes).
As is clear from FIG. 5, it was found that addition of ammonia is effective for dechlorination at any temperature for dechlorination of a soft vinyl chloride material.

Example 6
As a sample, a commercially available vinyl chloride pipe (trade name: Hishi Pipe, manufactured by Mitsubishi Plastics Co., Ltd.) containing hard vinyl chloride as a main component was used, and the reaction temperature and pressure were 230 ° C./2.8 MPa, 250 ° C./4. The reaction was carried out with respect to the aqueous ammonia solution and distilled water in the same manner as in Example 3 except that the reaction time was 10 MPa and 40 minutes, and the dechlorination rate was measured. The results are shown in Table 1.

  As is clear from Table 1, also for the dechlorination of hard vinyl chloride, it was found that addition of ammonia was effective for dechlorination at any temperature.

Example 7
As a sample, a commercially available wrapping film for food packaging made of polyvinylidene chloride (trade name: NEW Kurewrap, manufactured by Kureha Chemical Industry Co., Ltd.) was used, and the reaction temperature and pressure were 200 ° C./1.6 MPa, 220 ° C./2.3 MPa. In the same manner as in Example 3 except that the reaction time was set to 5, 10, and 20 minutes, the aqueous ammonia solution and distilled water were reacted to measure the dechlorination rate. The results are shown in Table 2 and FIG.

FIG. 6 is a graph showing the change over time in the dechlorination rate in which the results of Table 2 are plotted. The vertical axis represents the dechlorination rate (%), and the horizontal axis represents the reaction time (minutes).
As is clear from FIG. 6, it was found that addition of ammonia was effective for dechlorination at any temperature for dechlorination of polyvinylidene chloride material (wrapping film for food packaging).

Example 8
As a sample, 50 mg of powder of decabromodiphenyl ether (manufactured by Wako Pure Chemical Industries, Ltd., purity 98%) used as a flame retardant was used, the reaction temperature was 260 ° C. and 340 ° C., and the reaction time was 5, 10, 20 minutes. Except that, the reaction was performed with respect to the aqueous ammonia solution and distilled water in the same manner as in Example 3, and the debromination rate was measured.
The measurement results are shown in FIG. FIG. 7 is a graph showing the change over time in the debromination rate, with the vertical axis representing the debromination rate (%) and the horizontal axis representing the reaction time (minutes).
As is apparent from FIG. 7, it was found that the aqueous ammonia solution was very effective for debromination.

FIG. 1 is a graph showing the change over time in the dechlorination rate (Example 1). FIG. 2 is a graph showing an Arrhenius plot for the dechlorination rate constant at each temperature (Example 2). FIG. 3 is a graph showing the change over time in the dechlorination rate (Example 3). FIG. 4 is a graph showing the change over time in the dechlorination rate (Example 4). FIG. 5 is a graph showing the change over time in the dechlorination concentration (Example 5). FIG. 6 is a graph showing the change over time in the dechlorination rate (Example 7). FIG. 7 is a graph showing the change over time in the debromination rate (Example 8).

Claims (3)

  A method for dehalogenating a halogen-containing polymer, comprising contacting an ammonia-containing aqueous solution heated to 180 ° C. or more and less than 350 ° C. with the halogen-containing polymer.   The method for dehalogenating a halogen-containing polymer according to claim 1, wherein the concentration of the ammonia-containing aqueous solution is 0.006 to 10 mol / l. The method for dehalogenating a halogen-containing polymer according to claim 1 or 2, wherein the halogen-containing polymer is polyvinyl chloride or polyvinylidene chloride.

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