JPH10324769A - Dechlorinating treatment of waste resin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a dechlorinating treatment of waste resin materials, excellent in practicality and capable of removing chlorine from the waste materials containing chlorine without generating chlorine gas by passing through a process of treating the material in a supercritical water. SOLUTION: This method for dechlorinating waste resin materials containing chlorine comprises a process of adding a basic compound (e.g.; calcium hydroxide) into the waste resin materials containing chlorine with melting and kneading, and a process for treating the mixed and kneaded material in a subcritical or a critical state water. Further, as the above-mentioned waste materials, car shredded dusts can be used and it is preferable to set a temperature in the above mixing and kneading at <=300 deg.C, and a temperature in the above treatment at >300 deg.C and <=400 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for dechlorinating resin waste containing chlorine such as vinyl chloride.

[0002]

2. Description of the Related Art Vinyl chloride contained in waste plastic is rapidly decomposed at a temperature of 250 ° C. or more and generates hydrogen chloride gas, which causes problems such as corrosion of a combustion furnace. Therefore, when the mixed resin waste containing vinyl chloride is used as a solid fuel, a hydrogen chloride gas treatment facility is required. Therefore, it has been proposed to neutralize and remove generated hydrogen chloride gas by blowing caustic soda or slaked lime in a flue or furnace.

[0003] However, it is difficult to prevent the furnace body from being corroded in the treatment in the flue. In the treatment in the furnace, calcium chloride or the like once formed is heated at a high temperature in the furnace and coexisting with CO ₂ and H ₂ .
_It decomposes under the influence of ₂ O and the like to generate hydrogen chloride gas again, so that there is a problem that the processing efficiency is low. Further, since these processing equipment processes a large amount of combustion exhaust gas, a large-scale one is required, which causes an increase in combustion cost. Therefore, when using mixed resin waste containing vinyl chloride as a solid fuel, it is necessary to remove chlorine contained in advance.

Therefore, as a method of removing chlorine, a method of treating a waste vinyl chloride material in an aqueous alkaline solution at 300 ° C. for 1 hour and dechlorinating the same has been disclosed (a public symposium sponsored by the Japan Society of Resources and Materials). Proceedings of "Development of Hydrothermal Chemistry for Organic Resources and Energy Recycling Process" p.
156-p. 171). In this method, waste vinyl chloride is treated in an aqueous alkaline solution at 300 ° C. for 1 hour to dechlorinate.

[0005]

However, the conventional method described above is not practical because the processing time is long and is not suitable for continuous processing. Further, since an alkaline aqueous solution is used, the waste liquid after chlorine removal needs to be neutralized and then discharged.

The present invention has been made in view of the above-mentioned conventional problems, and provides a highly practical method for dechlorinating resin waste material which can remove chlorine from waste material containing chlorine without generating hydrogen chloride gas. What you want to do.

[0007]

The invention according to claim 1 comprises a step of adding a basic compound to a chlorine-containing resin waste material and melt-kneading the same, and a step of treating the kneaded product in water in a subcritical or critical state. The method is a method for dechlorinating resin waste material.

[0008] In the present invention, water in a subcritical state is a temperature of 300 ° C or more and less than 374 ° C, and a pressure of 90 atm or more and 22
It refers to water under an environment of less than 0 atm. The water in a critical state refers to water in an environment at a temperature of 374 ° C. or more and a pressure of 220 atm or more. Hereinafter, when expressing both the subcritical state or the critical state, it is referred to as (sub) critical state.

The operation and effect of the present invention will be described.
The present invention relates to a resin waste material to which a basic compound has been added,
Treated in critical water. This water does not contain alkali such as sodium hydroxide. Therefore, the diffusion rate of water into the resin waste material is increased, and chlorine in the resin waste material can be quickly removed by the water.

More specifically, it is known that the dechlorination of vinyl chloride is promoted by high-temperature, high-pressure subcritical water. (Open Symposium "Development of Hydrothermal Chemistry for Organic Resources and Energy Recycling Process" hosted by the Society of Natural Resources and Materials)
Proceedings p. 44 to p. 56) When dechlorinating vinyl chloride, it is important that vinyl chloride and subcritical water come into contact as quickly as possible. For vinyl chloride in mixed resin waste, the diffusion rate of water into solids Is faster the faster.

That is, when a kneaded product of a resin waste material and a basic compound is treated in (sub) critical water, water diffuses and permeates into the kneaded material. The moving speed (diffusion speed) of water into the resin waste material controls the dechlorination speed.

When sodium hydroxide or the like is dissolved in water,
The temperature and pressure at which water reaches a critical state (ie, critical temperature and critical pressure) increase. It is also known that the diffusion rate of water increases as it approaches the critical point (Reference;
Supercritical fluid science and technology, Sankyo Business, supervised by Shozaburo Saito). Therefore, the diffusion rate of water at the same temperature is expected to decrease when sodium hydroxide or the like is dissolved.
Since only water is used in the present invention, the diffusion rate of water is considered to be higher in the present invention than in a treatment using an alkaline aqueous solution as in the prior art.

In the present invention, since the basic compound is added to the resin waste material, most of the generated hydrogen chloride gas is
It reacts with the basic compound and is present in the resin waste as an alkali salt. The alkali salt is easily dissolved in the water diffused and permeated into the resin waste material as described above, and is discharged out of the resin waste material by the (sub) critical water extraction action.

Therefore, according to the present invention, dechlorination can be performed in a short time even at the same temperature as compared with the prior art. Further, since the processing can be performed in a short time, continuous processing can be performed, and the processing cost can be reduced. Therefore, the dechlorination method of the present invention is excellent in practicality.

The basic compound is not particularly limited, such as a weak alkali and a strong alkali, but a weak alkali is preferable from the viewpoint of easy handling. As the basic compound, for example, calcium hydroxide, calcium carbonate and the like can be used. The addition amount of the basic compound varies depending on the chlorine content in the resin waste material, but is preferably at least the chemical equivalent to the chlorine content.

If the melt-kneading temperature is too high, chlorine-containing compounds such as vinyl chloride are thermally decomposed during extrusion molding,
Since a large amount of gas is generated, a temperature of 300 ° C. or less is desirable.

The treatment temperature in (sub) critical water is as follows:
The temperature is preferably higher than 300 ° C. and 400 ° C. or lower. If the temperature is lower than 300 ° C., the dechlorination decreases. If the temperature exceeds 400 ° C., the olefin resin (polypropylene resin, polyethylene resin, etc.) in the resin waste may be thermally decomposed and liquefied.

The dechlorination treatment method of the present invention can be used for waste materials of any resin containing chlorine. In particular,
Car shredder dust, waste home appliances shredder dust,
It can be used for dechlorination of resin waste such as vinyl chloride products, but is not limited to these.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment Example A method for dechlorinating resin waste according to an embodiment of the present invention will be described with reference to FIG. In this example, as shown in FIG. 1, a basic compound such as calcium hydroxide was previously added to chlorine-containing resin waste material (eg, car shredder dust) containing vinyl chloride and the like, and these were added at 200 ° C.
The mixture is melt-kneaded at the temperature described above and extruded to obtain a molded body. Next, the molded body was placed in an autoclave with stirring together with water,
Heating is performed under a pressure of 0 atm at a temperature higher than 300 ° C. and 400 ° C. or lower. Thereby, the compact is treated with water in the (sub) critical state. Thereafter, the molded body is washed and dried by a hot air drier or the like. Thus, a dechlorinated resin waste material is obtained.

Example 1 A metal component, urethane foam,
10% by weight of sodium carbonate was added to the separated dust from which the fiber component had been removed, and the mixture was melt-kneaded in a twin-screw extruder (resin temperature 200 ° C.) and extruded to obtain a molded product. The compact was cooled and pulverized to obtain a pulverized product.

5 g of the pulverized material is placed in an autoclave (50 ml capacity) with stirring together with 25 g of water, and heated at 350 ° C. under a pressure of 165 atm for a predetermined time (5 to 40 minutes) to reduce the pulverized material to water in a subcritical state. The processing in was performed.

Example 2 In this example, slaked lime was used as a basic compound.
Resin waste was treated. The amount of slaked lime added to the fractionated dust was 10% by weight. Others are the same as the first embodiment.

COMPARATIVE EXAMPLE In this example, in a subcritical alkaline aqueous solution,
Resin waste was treated. That is, the separated dust obtained by removing the metal component, urethane foam, and fiber component from the car shredder dust was melt-kneaded with a twin-screw extruder (resin temperature: 200 ° C.) and extruded to obtain a molded product. The compact was cooled and pulverized to obtain a pulverized product.

5 g of the pulverized material was put into an autoclave (50 ml capacity) with stirring together with 25 g of a 5% aqueous sodium hydroxide solution, and was heated at 350 ° C. under a pressure of 165 atm.
By heating for a predetermined time (5 to 40 minutes), the pulverized material was treated in a subcritical alkaline aqueous solution.

(Experimental Example) In this example, the chlorine content was measured for the processed products in Examples 1 and 2 and Comparative Example. Each treated material was filtered, the solid was burned in oxygen, and the generated gas was dissolved in distilled water and titrated with an aqueous silver nitrate solution to determine the amount of chlorine. This quantification method is a method according to JIS K6722. The results are shown in FIGS. FIG. 2 shows the chlorine content of the processed products of Example 1 and Comparative Example, and FIG. 3 shows the chlorine content of the processed products of Example 2 and Comparative Example.

As is known from FIGS. 2 and 3, the chlorine content after the subcritical treatment was significantly different between Examples 1 and 2 and Comparative Example 1 when the treatment time was short. On the other hand, when the processing time became longer, no remarkable difference was observed. This indicates that the methods of Examples 1 and 2 can realize dechlorination in a short time.

In the first and second embodiments, the treatment is performed using water. On the other hand, in the comparative example, the treatment is performed using an alkaline aqueous solution. The diffusion rate of water into resin waste is faster than that of alkaline aqueous solution. Therefore, according to Examples 1 and 2, the alkali salt generated by the reaction of chlorine and the basic compound in the resin waste material can be removed outside the resin waste material in a short time, and the processing time can be reduced. it is conceivable that.

[0028]

According to the present invention, it is possible to provide a method for dechlorinating resin waste material, which is capable of removing chlorine from chlorine-containing waste material without generating hydrogen chloride gas and which is excellent in practical use. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for dechlorinating resin waste material in an embodiment.

FIG. 2 is a diagram showing the chlorine content of the processed products of Example 1 and Comparative Example.

FIG. 3 is a diagram showing the chlorine content of the processed products of Example 2 and Comparative Example.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 26 (72) Inventor Tatsuta Tatsuta Yokomichi 41, Oku-cho, Nagakute-cho, Aichi-gun, Aichi Prefecture 1 Toyota Central Research Laboratory Co., Ltd. (72) Inventor Kenzo Fukumori 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Kazuya Sano, 41-Yokomichi, Yokomichi, Nagakute-machi, Aichi-gun, Aichi 1 Toyota Central Research Institute, Inc. (72) Inventor Takuji Kajiwara 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Kunihiko 1 Toyota Motor Town Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Katsura Kimura 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (1)

[Claims] 1. A resin waste material comprising: a step of adding a basic compound to chlorine-containing resin waste material and melt-kneading; and a step of treating the kneaded material in subcritical or critical water. Dechlorination treatment method.