JP2003020362A - Method for treating resin mixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which can treat a mixture of a polyolefine and a vinyl chloride resin without separating them each other to recover a recyclable compound. SOLUTION: The method comprises a first process and a second process, wherein the first process is a process for treating a mixture of a polyolefine and a vinyl chloride resin with subcritical water in the presence of a hydrogen chloride scavenger so that hydrogen chloride is eliminated from the vinyl chloride resin and removed together with the hydrogen chloride scavenger; and the second process is a process for treating a mixture of a polyolefine and a dehydrochlorinated vinyl chloride resin residue with subcritical water so that the dehydrochlorinated vinyl chloride resin residue is selectively decomposed to convert to a water-soluble polymer, followed by separating the polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of treating a mixture of vinyl chloride resin and polyolefin, which is useful for treating wastes of electric wires and cables.

[0002]

2. Description of the Related Art Electric wires and cables use various rubber and plastic materials such as cross-linked polyethylene as a covering material, but since these are not easily decomposed in the natural world, their disposal after disposal becomes a problem. ing.

Under these circumstances, recently, a method of hydrolyzing and / or thermally decomposing plastics using water in a supercritical state or a subcritical state as a reaction solvent has been devised, and a large amount of plastic waste is treated at high speed. Since it is possible to recover reusable low to medium molecular weight compounds, it is expected to be applied to the waste treatment of electric wires and cables as described above.

[0004]

By the way, in electric wires and cables, as represented by CV cables (cross-linked polyethylene insulation vinyl sheath cables), insulation coating materials and sheath materials are generally used because of differences in required characteristics. Different plastic materials are used. Therefore, such dissimilar plastic materials will be mixed in the electric wire / cable waste, and in order to utilize the above decomposition technology using supercritical water, etc., these dissimilar plastic materials must be mixed. It is necessary to process each material separately.

As a technique for separating such dissimilar materials, a specific gravity separation method for separating by utilizing the difference in specific gravity has been conventionally known. However, a small amount of metal powder (usually copper powder), which is a conductor material, is also mixed in the plastic recovered from the waste of electric wires and cables. this is,
This is because the conductor material that could not be sufficiently separated when recovering the plastic covering material from the electric wire / cable waste is mixed into the inside by the heat when crushing the plastic. Then, it is difficult to separate the dissimilar plastic materials collected from the electric wire / cable waste.

[0006] Therefore, there is a demand for a technique capable of individually treating such wastes containing different kinds of materials without separating the different kinds of materials. In particular, in the electric wire / cable field where such technology is required, since a large amount of mixed waste of polyolefin such as polyethylene and vinyl chloride resin is discharged, it is difficult to mix polyolefin and vinyl chloride resin. There is a strong demand for a treatment technology capable of treating waste without separating polyolefin and vinyl chloride resin.

The present invention has been made in consideration of such conventional circumstances, and is a resin capable of treating a mixed waste of a polyolefin and a vinyl chloride resin without separating the polyolefin and the vinyl chloride resin. It is intended to provide a method of treating a mixture.

[0008]

In order to achieve the above object, the method for treating a resin mixture according to the first aspect of the present invention is a method for treating a mixture of a vinyl chloride resin and a polyolefin in the presence of a hydrogen chloride scavenger. A first step of treating with subcritical water to desorb hydrogen chloride from the vinyl chloride resin and removing it together with a hydrogen chloride scavenger, and a mixture of the dehydrochlorinated vinyl chloride resin residue and a polyolefin Is treated with subcritical water to selectively decompose the dehydrochlorinated vinyl chloride resin residue, reform it into a water-soluble polymer, and separate it. I am trying.

According to the present invention, a reusable compound (water-soluble polymer) can be recovered by treating a mixture of a vinyl chloride resin and a polyolefin without separating the vinyl chloride resin and the polyolefin. .

A method for treating a resin mixture according to a second aspect of the present invention is the same as the method for treating a resin mixture according to the first aspect.
The water-soluble polymer in the second step is characterized by being mainly polyvinyl alcohol.

According to this structure, the packaging film, the fiber,
It is possible to recover highly reusable polyvinyl alcohol, which is useful as a material for paints and emulsifiers.

In the method for treating a resin mixture according to the above invention, as described in claim 3, the treatment temperature with subcritical water in the first step is 200 ° C. to 320 ° C. and the treatment pressure is 0.1 MPa to 100 MPa. It is preferable that If the treatment temperature or the treatment pressure is out of the above range, desorption of hydrogen chloride from the vinyl chloride resin becomes insufficient,
Alternatively, the vinyl chloride resin is not limited to dehydrochlorination, and further decomposition may occur.

Further, as described in claim 4, the treatment temperature with the subcritical water in the second step is 200 ° C. to 320 ° C.
It is preferable that the temperature is set to ℃ and the processing pressure is set to 0.1 MPa to 100 MPa. If either of the treatment temperature and the treatment pressure deviates from the above range, the dehydrochlorinated vinyl chloride resin residue will be insufficiently modified into a water-soluble polymer, or conversely, decomposition will proceed excessively to cause water-soluble decomposition. There is a possibility that a reactive polymer may not be obtained. Further, not only the vinyl chloride resin residue but also the polyolefin may be decomposed.

A method for treating a resin mixture according to a fifth aspect of the present invention is the method for treating a resin mixture according to the above-mentioned method, further comprising, after the second step, at least high temperature subcritical water or supercritical water having a temperature of higher than 320 ° C. It is characterized by performing a third step of treating with water to modify the polyolefin into a reusable compound.

According to this structure, not only a reusable modified vinyl chloride resin but also a reusable modified polyolefin can be obtained from a mixture of a vinyl chloride resin and a polyolefin.

In the method for treating a resin mixture according to claim 5, the treatment temperature with subcritical water or supercritical water in the third step is 320 ° C.
It is preferable that the treatment pressure is set to ˜450 ° C. and the processing pressure is set to 0.1 MPa to 100 MPa. If either the treatment temperature or the treatment pressure is out of the above range, the decomposition of the polyolefin may proceed excessively, or conversely, the decomposition may not proceed sufficiently and a reusable modified polyolefin product may not be obtained.

In the method for treating a resin mixture according to the above invention, as described in claim 7, a great effect can be obtained when the hydrogen chloride scavenger is a hydroxide of an alkali metal or an alkaline earth metal. it can.

Further, as described in claim 8, when the mixture of the vinyl chloride resin and the polyolefin is recovered from the waste, it is difficult to separate the vinyl chloride resin and the polyolefin. , A great effect can be obtained, and among them, as described in claim 9,
When such waste includes electric wire / cable waste, it is more difficult to separate the vinyl chloride resin and the polyolefin, so that a particularly large effect can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart showing a method for treating a resin mixture according to an embodiment of the present invention.

As shown in the figure, in the present embodiment, first, a mixture of vinyl chloride resin (abbreviated as PVC in the figure) and polyolefin (abbreviated as PO in the figure) was pulverized as needed. Then, in the presence of a hydrogen chloride scavenger, it is contacted with subcritical water to desorb hydrogen chloride from the vinyl chloride resin and reform it to a vinyl chloride resin reformate (1). The hydrogen chloride desorbed from the vinyl chloride resin is captured by the hydrogen chloride scavenger and discharged out of the system.

Subcritical water is generally the critical point of water (temperature 37
It means water that is near supercritical at a temperature and pressure close to the critical point, as compared to water (supercritical water) at 4.2 ° C and pressure 22.1MPa). It is preferable to adjust the temperature within the range of 200 ° C to 320 ° C and the pressure within the range of 0.1 MPa to 100 MPa. If either the treatment temperature or the treatment pressure is out of the above range, the desorption of hydrogen chloride from the vinyl chloride resin may be insufficient, or the vinyl chloride resin may not be dehydrochlorinated and further decomposed. There is. More preferable processing condition is that the temperature is 250 ° C to 300 ° C.
C, pressure is in the range of 0.1 MPa to 50 MPa. Furthermore, the pressure is preferably equal to or lower than the saturated vapor pressure in terms of reaction efficiency. The treatment time is usually in the range of 10 to 30 minutes, though it varies depending on the size of the object to be treated and the amount of vinyl chloride resin.

Examples of the hydrogen chloride scavenger include alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide and calcium hydroxide, and iron (Fe). The use of alkali metal or alkaline earth metal hydroxides is preferred.
This hydrogen chloride scavenger is preferably used in an amount sufficient to trap the hydrogen chloride that is released.

The vinyl chloride resin reformed product (1) produced by this treatment basically depends on the type of hydrogen chloride scavenger and the treatment conditions, but basically it is a hydroxyl chloride such as sodium hydroxide. If you use a
An aliphatic structure partially containing a double bond having an oxygen-containing group such as a cross-linking oxygen produced by dehydration of -OH groups or -OH groups introduced by the hydrolysis, or a polyene. The main chemical structure is a simple aromatic ring formed by the cyclization of, and in the case of iron, the polyene produced by the dehydrochlorination reaction is complicated from the simple aromatic ring bonded intermolecularly and intramolecularly. It is considered that the basic structure is a condensed aromatic ring and an aliphatic or residual polyene produced by hydrogen transfer during the formation of the aromatic ring. In the case of iron as well, although it was less than that of hydroxide, it was introduced by hydrolysis.
It contains oxygen-containing groups such as bridging oxygen due to intermolecular or intramolecular dehydration between OH and -OH.

On the other hand, the polyolefin is
It is not decomposed and its chemical structure does not change.

Next, these vinyl chloride resin modified products
The mixture of (1) and the polyolefin remaining without being decomposed,
Treat again with subcritical water. By this treatment, the vinyl chloride resin modified product (1) is decomposed, and the vinyl chloride resin modified product (2) is mainly composed of a polyvinyl alcohol structure polymer having an aliphatic structure containing an -OH group and a partial aromatic ring structure.
Is reformed to. On the other hand, the polyolefin does not decompose and its chemical structure does not change even at this stage.

As treatment conditions with subcritical water in this step, it is preferable that the temperature is 200 ° C. to 320 ° C. and the pressure is 0.1 MPa to 100 MPa. If either of the treatment temperature and the treatment pressure is out of the above range, the dehydrochlorinated vinyl chloride resin residue is insufficiently reformed into a water-soluble polymer, or conversely, it is decomposed too much and water There is a possibility that a reactive polymer may not be obtained. Furthermore, the decomposition of the polyolefin may start. More preferable treatment conditions are a temperature of 250 ° C. to 300 ° C. and a pressure of 0.1 MPa to 50 MPa. By treatment under such conditions, the vinyl chloride resin modified product (1) has a polyvinyl alcohol structure. Is modified into a polymer having.

The polymer having the polyvinyl alcohol structure is soluble in hot water having a temperature of 100 ° C. or higher and a pressure of saturated steam pressure or higher. Therefore, the vinyl chloride resin modified product (2) produced in the above step and the polyolefin are treated with hot water to separate the vinyl chloride resin modified product (2) mainly composed of a polymer having a polyvinyl alcohol structure from the polyolefin. Can be collected. That is, the hot water in which the vinyl chloride resin modified product (2) is dissolved may be cooled by, for example, a solid-liquid separator, and the vinyl chloride resin modified product (2) may be precipitated and recovered.

On the other hand, the remaining polyolefin is treated with subcritical water or supercritical water to be reformed into a reusable compound. Here, it is treated with subcritical water or supercritical water having a temperature of at least 320 ° C. or higher. The processing conditions in this step are as follows: the temperature is 320 ° C to 450 ° C and the pressure is 0.1M.
Pa to 100 MPa is preferable. If either of the treatment temperature and the treatment pressure is out of the above range, the decomposition of the polyolefin may proceed excessively or, on the contrary, the decomposition may not proceed sufficiently and a reusable modified polyolefin product may not be obtained.

When the polyolefin is a cross-linked polyolefin, the treatment in this step is carried out at a temperature of 320 ° C to 420 ° C.
It is preferable to adjust the temperature and the pressure in the range of 0.1 MPa to 50 MPa. By treating under such conditions, the crosslinked polyolefin is modified into an uncrosslinked polyolefin having extremely high reusability.

The mixture of the vinyl chloride resin and the polyolefin treated in the present invention contains a metal powder recovered from the products using these resins, for example, the wastes such as electric wires and cables. Good. The metal powder can be removed at the stage of recovering the polyolefin or its modified product.

In such a method, a mixture of a vinyl chloride resin and a polyolefin can be treated without separating the polyolefin and the vinyl chloride resin to modify each of them into a reusable compound for recovery. it can.

In the present invention, when performing the above-mentioned treatment, not only a semi-batch type apparatus as shown in Examples described later but also a batch type or continuous reaction type processing apparatus can be used.

[0034]

EXAMPLES Next, examples of the present invention will be described, but the present invention is not limited to the following examples.

The processing apparatus shown in FIG. 2 was used in the examples. That is, as shown in FIG. 2, this apparatus includes a pressure-resistant reaction vessel 1 equipped with an electric furnace 1a and a first reactor containing a 0.05N sodium hydroxide aqueous solution obtained by dissolving sodium hydroxide in pure water. A solvent tank 2, a second solvent tank 3 containing only pure water, and a sodium hydroxide aqueous solution and pure water from the first and second solvent tanks 2 and 3 are respectively fed into the pressure-resistant reaction container 1. Pump 4,
5, a solid-liquid separator 6 that cools a gas component discharged from the pressure-resistant reaction container 1 and separates a solid and a liquid generated by this cooling, and a pipe 7 that connects these devices. A line heater 8 is attached to a pipe 7 that connects the pressure-resistant reaction container 1 and the solid-liquid separator 6, and a pipe 10 equipped with a pressure regulator 9 is opened above the solid-liquid separator 6. is doing. In the figure, 11 is a thermometer for measuring the temperature in the pressure resistant reaction vessel 1.

Example As the article to be treated, a 1 mm thick sheet made of soft vinyl chloride resin (resin content 50% by weight, Mw = 120,000) and a 1 mm thick sheet made of low density polyethylene (Mw = 100000) were used. . Each sheet was previously mixed with 10% by weight of copper powder.

First, each of these sheets was crushed into fine particles having a particle size of about 2 to 3 mm, and 0.5 g of each was weighed out and thoroughly mixed. Then, a 0.05N aqueous sodium hydroxide solution was continuously fed into the pressure-resistant reaction vessel 1 from the first solvent tank 2 by a pump 4 at a flow rate of 3 ml / min to maintain the pressure in the pressure-resistant reaction vessel 1 at 10 MPa. . When the pressure is stable, the temperature inside the pressure resistant reactor 1 is set to 270 ° C.
After raising the temperature to 30 minutes and maintaining it for 30 minutes as it is, the introduction of the sodium hydroxide aqueous solution is stopped, and pure water is continuously fed from the second solvent tank 3 to the pressure resistant reaction vessel 1 at a flow rate of 3 ml / min by the pump 5. It is.

After that, the pressure in the pressure resistant reaction vessel 1 was set to 25 MPa.
After 30 minutes, the cooling of the pressure resistant reactor 1 (air cooling with a fan) was started. It should be noted that although the temperature inside the pressure-resistant reaction vessel 1 drops when the pressure rises, it was left as it was, and the line heater 8 was also maintained at 270 ° C. After the temperature inside the pressure-resistant reaction vessel 1 returned to room temperature, the pressure was returned to normal pressure, and the solid contents inside the pressure-resistant reaction vessel 1 and the solid-liquid separator 6 were individually collected.

Each of the collected solids was vacuum dried (10 mmHg or less) at 80 ° C. for 5 hours and weighed. The solid content in the pressure resistant reactor 1 was about 0.6 g, and the solid-liquid separator 6 was used.
The solid content therein was about 0.14 g. In addition, infrared spectroscopic analysis of each of these solids confirmed that the solids in the pressure resistant reactor 1 were polyethylene and the solids in the solid-liquid separator 6 were mainly polyvinyl alcohol. In addition,
Although copper powder was accumulated at the bottom of the pressure-resistant reaction vessel 1, these could be easily separated from the resin solid content. The separated copper powder was similarly dried and weighed.
It was 0.1 g.

[0040]

As described above, according to the present invention,
The mixture of polyolefin and vinyl chloride resin can be treated without separating the polyolefin and vinyl chloride resin.

[Brief description of drawings]

FIG. 1 is a flow chart showing a method for treating a resin mixture according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a processing apparatus used in an embodiment of the present invention.

[Explanation of symbols]

1 ... Pressure resistant reactor 2 ... the first solvent tank 3 ... Second solvent tank 4, 5 ......... Pumps 6 ... Solid separator 9 ... Pressure regulator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyoshi Furumura             20 Kitakanzan, Otakamachi, Midori-ku, Nagoya-shi, Aichi             No. 1 Chubu Electric Power Co., Inc. (72) Inventor Susumu Hirai             2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa             No. Showa Densen Denki Co., Ltd. (72) Inventor Takao Nakamoto             2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa             No. Showa Densen Denki Co., Ltd. (72) Inventor Hitoshi Shindate             2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa             No. Showa Densen Denki Co., Ltd. (72) Inventor Hiroaki Morita             2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa             No. Showa Densen Denki Co., Ltd. F-term (reference) 4F301 AA12 AA17 AD01 AD02 CA09                       CA24 CA72 CA73

Claims (9)

[Claims] 1. A mixture of a vinyl chloride resin and a polyolefin is treated with subcritical water in the presence of a hydrogen chloride scavenger to desorb hydrogen chloride from the vinyl chloride resin and remove it together with the hydrogen chloride scavenger. A first step, and treating the mixture of the dehydrochlorinated vinyl chloride resin residue and the polyolefin with subcritical water to selectively decompose the dehydrochlorinated vinyl chloride resin residue, A second step of modifying into a water-soluble polymer and separating the polymer, the method for treating a resin mixture. 2. The method for treating a resin mixture according to claim 1, wherein the water-soluble polymer in the second step is mainly polyvinyl alcohol. 3. The treatment temperature with subcritical water in the first step is 200 ° C. to 320 ° C., and the treatment pressure is 0.1 MPa to.
The method for treating a resin mixture according to claim 1 or 2, wherein the method is 100 MPa. 4. The treatment temperature with subcritical water in the second step is 200 ° C. to 320 ° C., and the treatment pressure is 0.1 MPa to.
The method for treating a resin mixture according to claim 1, wherein the method is 100 MPa. 5. After the second step, the polyolefin is further treated with high-temperature subcritical water or supercritical water having a temperature of at least 320 ° C. to reform the polyolefin into a reusable compound. The method for treating a resin mixture according to any one of claims 1 to 4, characterized in that the step (1) is performed. 6. The treatment temperature with subcritical water or supercritical water in the third step is 320 ° C. to 450 ° C., and the treatment pressure is 0.1 MPa to 100 MPa.
A method for treating a resin mixture as described. 7. The method for treating a resin mixture according to any one of claims 1 to 6, wherein the hydrogen chloride scavenger is a hydroxide of an alkali metal or an alkaline earth metal. 8. The method for treating a resin mixture according to claim 1, wherein the mixture of vinyl chloride resin and polyolefin is recovered from waste. 9. The method for treating a resin mixture according to claim 8, wherein the waste includes electric wire / cable waste.