JP2001220460A - Method for treating resin waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively recovering and fractionating bromine and antimony as antimony trioxide from TV housing wastes, by which treated resins can be used as a solidified fuel. SOLUTION: This method for treating resin wastes is characterized by melting TV housing wastes in a reactor having a structure similar to those of figure 2 and figure 3 (not shown) at a temperature of 280 to 370 deg.C in a treating surface area of 5 to 100 m2 and at a specific energy value of 10 to 300 MJ/m3. Bromine and antimony can effectively be recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention separates and recovers both components by vaporizing and separating bromine and antimony from resin waste containing a large amount of bromine, particularly from TV casing waste.
This is a method for producing a solidified fuel.

[0002]

2. Description of the Related Art Styrene resin compositions are often used as TV housing materials. In order to satisfy the UL standard, a flame retardant and a flame retardant auxiliary are kneaded, and in particular, a bromine compound is kneaded at 10 to 20% by weight. For this reason, the housing resin material contains 12 to 15% by weight of bromine, and cannot be easily incinerated for disposal.
Also, diantimony trioxide added as a flame retardant aid during combustion reacts with the resin component and the flame retardant to change to highly volatile antimony tribromide. When the Home Appliance Recycling Law comes into effect in 2001, home appliance manufacturers will be required to collect and the home appliance manufacturers will have to reuse the collected materials. While metal materials and glass parts used in home appliances are expected to be reused, housing materials are not. Since a large amount of bromine is contained in the burning treatment, brominated dioxin and benzofuran may be generated during burning. In recent years, the number of landfills for final disposal has been decreasing, and it is becoming increasingly difficult.

As a method for treating the waste, a continuous treatment method using an extruder can be considered, but although bromine contained in the treated resin can be removed well, it takes time to remove the bromine, and for this reason, it is difficult to remove the bromine. The generated organic antimony compound and high-boiling-point hydrocarbon are contained in the recovered gas component, and when antimony is taken out as a valuable material, there is a problem that diantimony trioxide has low purity and is difficult to reuse.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for removing and recovering bromine and antimony in a short period of time and with high yield so that the treated resin can be used as a solidified fuel. Is to provide a method for recovering wastewater.

[0005]

Means for Solving the Problems The inventors of the present invention increased the efficiency of stirring a treating agent and waste with a styrenic resin composition containing a bromine compound by using a device having a rotary stirring function, thereby obtaining bromine and antimony. Changed to hydrogen bromide and antimony tribromide, and both were easily recovered, and it was found that the remaining resin contained almost no bromine and antimony in the gas recovery components.

That is, the present invention relates to (1) a method for continuously separating and recovering bromine and antimony from a styrene-based resin composition containing a bromine-based flame retardant and an antimony compound using an apparatus having a rotary stirring function. The effective processing surface area of the rotary stirring device is 5 m ^{2 to} 1
00 m ^2, and the temperature of the styrene resin composition is 280 to 370 ° C. (2) The value of the specific energy applied to the resin waste treated by the apparatus having a rotary stirring function until the resin temperature reaches 300 ° C. is 10 MJ / m ^{3 to} 300 MJ / m ^3. The method according to (1).

(3) The method according to (1) or (2), wherein the polystyrene-based treating agent is added to the styrene-based resin composition in an amount of 20 to 70% by weight. (4) The apparatus having the rotary stirring function operates at a reduced pressure of 13.
The method according to any one of (1) to (3), wherein the pressure is 3 kPa or less. (5) A solid fuel having a bromine content of 2 wt% or less, obtained by the method of (1) to (4).

(6) The gas generated by the above methods (1) to (4) is reacted with an aqueous alkali solution to obtain a gas having a pH of 12 to 7.
A method of extracting diantimony trioxide from the styrenic resin composition in the range of. (7) diantimony trioxide obtained by the methods (1) to (4) and (6). It is.

Hereinafter, the present invention will be described in detail. The apparatus having a rotary stirring function of the present invention (hereinafter referred to as a rotary kneader) is, for example, a kneader or an extruder for kneading a resin, or a stirrer mounted in a decomposition furnace, and the resin to be processed is rotated. A device that has the function of updating the surface. The brominated flame retardant of the present invention refers to decabromodiphenyl ether, tetrabromobisphenol A, or a bromine content having an epoxy group or a hydroxyl group in the molecule of 70%.
Weight percent or more of a tabromized epoxy compound and hexabromobenzene.

The antimony compound of the present invention means antimony tribromide, alkylantimony (alkylstibine) or stibine compound. Separation and recovery of bromine and antimony in the present invention means that bromine and antimony are converted into volatile compounds and vaporized, and this gas is recovered and separated from resin components. The generated gas means a volatile bromine compound generated by the gas, for example, hydrogen bromide, antimony tribromide, alkylantimony and the like.

The specific energy described in the claims is an index indicating how much shear energy the resin to be treated has undergone, and how much the resin and the flame retardant or the flame retardant and the treatment agent are kneaded by shearing. Indicates As this value is larger, the flame retardant and the resin react more quickly. The specific energy _ev is defined as follows. e _v = η · (dγ / dt) · τ where (dγ / dt) is the average shear rate, η is the viscosity of the resin compound, and τ is the residence time, that is, the resin is heated until the resin temperature reaches 300 ° C. It refers to the specific energy incurred. That shows the specific energy processing agent resin or resin suffered by reactor internal preheating stage the e _v.

The effective treated surface area of the present invention indicates the degree of renewal of the volatile surface area for removing volatile bromine compounds and antimony compounds, and is defined as follows. here,
Device with rotary stirring function (hereinafter referred to as stirring reactor)
A method for inducing an effective surface area will be described for a rotary kneader. In this case, the resin melt exists inside the kneader in the form shown in the figure.

Consider a section of the barrel of the rotary kneader as viewed in a direction perpendicular to the screw direction as shown in FIG. At this time, when the screw rotates, the resin pool (FIG. 4) is stretched by the rotation, and a thin film (FIG. 5) is formed on the inner surface of the barrel. Hydrogen bromide and antimony compounds volatilize from the thin film-like resin coating. At this time, the film area dS _f per unit element length dL of the screw is represented by the following equation.

DS _f = (1/2) · D · [(4π−2
β) -3 (θ + α)] dL where D represents the internal diameter of the cylinder, π is the pi, β
Is the side opening angle (flank angle), and α is the vertex angle of the screw element. When removing volatile components from the resin component, it depends on how much the film surface area can be obtained during processing. This index is defined as a processing area. Accordingly, the processing surface area of the rotary kneader is as follows.

S _f = {dS _f = (１ ／) · D} [(4π
−β) −n (θ + α)] dL However, the integration range is from L = 0 to L = L0 where L0 indicates the barrel length of the rotary kneader, and n indicates the number of resin pools. Since the angle θ related to the resin pool is presumed to have little dependence on L when the screw element configuration is a desk type, the above equation can be simplified.

[0016] derive the effective processing surface area S _e at the time of processing from the processing surface area S _f obtained in this manner. This area indicates how much the surface has been degassed when the resin is treated by the rotary kneader, and is defined as follows. S _e = S _f · τ / t _f where τ is the residence time of the rotary kneader, t _f is the time until the treated surface is newly regenerated, and 1 / t _f is the treated surface per unit time. Indicates the number of updates. The value of this t _f is derived by the following equation.

T _f = (1/2) · (D / v) [(4π−
2β) / n−θ−α] Here, v indicates the speed of the screw on the inner surface of the barrel, and is (inner diameter of barrel) × (number of screw rotations). The above is an example of a rotary kneader (kneader), but if the reactor is of such a type that the surface is constantly updated for the above definition,
It is not limited to kneaders. For example, a packed tower in which an obstacle is filled in a reactor may be used. The effective surface area at this time is as follows: Se = a · N · F Where a is the surface area per packing and N
Indicates the number of packings present in the packed tower, and F indicates the surface renewal coefficient.

In the present invention, the term "continuously" does not mean that a resin composition containing a brominated flame retardant is reacted with a treating agent and then reacted in a batch process such as an autoclave. It refers to the continuous removal of bromine and antimony by continuously reacting both with a type kneader and degassing highly volatile bromine compounds.
The solid fuel having a bromine content of 2 wt% or less according to the present invention refers to a treated resin component obtained by the above treatment.

The reaction with the aqueous alkali solution of the present invention means that
This is a so-called neutralization reaction in which the gas generated in the above treatment is reacted with an aqueous solution having a pH of 7 or more. Here, the alkaline aqueous solution refers to an aqueous solution of, for example, caustic soda, caustic, sodium carbonate, baking soda, or slaked lime, and preferably has a pH of 10 or more.

TV casing waste, that is, a styrene-based bromine-based flame-retardant composition (hereinafter referred to as TV casing waste) is heated and reacted, or a polyolefin resin as a treating agent is kneaded and reacted. For effective degassing and removal, in a cylindrical vacuum tank, the molten resin is pressed against the inner wall of the vacuum tank, or a grid-like filling is put into the vacuum tank, and the molten resin is dropped. A method of constantly renewing the surface is preferable, but it is more preferable to use a stirring reactor, more preferably a rotary kneader. Further, it is necessary to devise the design of this screw in order to proceed the reaction effectively and quickly. The styrene-based resin referred to herein is polystyrene having a styrene content of 50% by weight or more, high impact polystyrene, styrene methacrylic acid copolymer, styrene acrylonitrile copolymer, styrene methacrylic acid copolymer, and styrene maleic anhydride copolymer. Say

The polyolefin-based treating agent of the present invention refers to a high-molecular alkane represented by the molecular formula CnH2n, ie, polypropylene or polyethylene, or a mutual copolymer thereof, or a wax, ie, a PE or PP wax. In the present invention, by devising the inside of the rotary kneader, the TV casing waste is effectively removed of bromine and antimony under a reduced pressure with a polyolefin-based treating agent.

Waste resin and treating agent (polyolefin-based
Pre-kneading before mixing in the rotary kneader.
What is good. An extruder is suitable for this
However, by increasing the compression ratio of this screw,
(Temperature of the styrene resin composition)
It is more preferable to design the pressure at 0 atm or more. Also, this kneading
When preheating and kneading with an extruder to improve
The specific energy that the resin incurs in the tumbling kneader is 30
Before reaching 0 ° C., 10 M-300 MJ / m ^Three, Preferred
Or 30M to 280MJ / m^Three, More preferably 80
M to 200 MJ / m^ThreeIt is good to set. 10MJ not yet
When full, the resin and treating agent do not react sufficiently,
If it exceeds, the reaction proceeds too much, resulting in a decrease in the resin recovery rate.

At a resin temperature of 300 ° C. or higher, the flame retardant and the resin begin to react, so that the effect of kneading is not obtained. Under these conditions, the flame retardant and the styrene-based resin or polyolefin-based treating agent can be completely dispersed and mixed, and can react completely.
The temperature of the rotary kneader was set to 80 ° C below the hopper. In the metalink zone, reach 220 ° C. The resin temperature at the outlet of the rotary kneader is preferably 300 ° C. At this time, the resin discharged from the rotary kneader is quenched with liquid nitrogen and then dissolved in a methyl ethyl ketone solution (1 wt% suspension, when the average particle size of the treating agent is determined by a sedimentation method using an Andracene pipette) Is 100μ
m or less. When the temperature reaches 280 ° C., the brominated flame retardant, diantimony trioxide and the treating agent begin to react for the first time, and antimony tribromide and HBr are generated.

Since this reaction is completed in about 3 minutes (300 ° C.), it is necessary to remove bromine and antimony within 5 minutes. This is because antimony tribromide reacts with a resin or gas to change into an organic antimony compound. Particularly in a batch system requiring a processing time or a system using a rotary kneader, the generation rate is high. Further, organic antimony is hydrolyzed with an aqueous alkali solution to form diantimony trioxide and higher alcohols. A metal higher alcoholate is produced, and the purity of diantimony trioxide formed by embracing diantimony trioxide is lowered.

[0025] The effective processing surface area in order to remove efficiently this tribromide antimony, 5~100m ² or less, preferably 20~100m ^2, more preferably 50~100m ²
Is good. When the effective surface area is less than 5 m ² , antimony tribromide reacts with the resin body to form alkylantimony, which lowers the purity of recovered antimony. When the effective surface area exceeds 100 m ² , the resin recovery rate decreases. Further, the resin temperature at this time is 280 to 370 ° C, preferably 280 ° C to 330 ° C.
° C, more preferably 280 ° C to 310 ° C. 280
If the temperature is lower than ℃, halogen and antimony are not sufficiently recovered. If it is too high, gasification is promoted not only by thermal decomposition of the resin itself, but also antimony tribromide further reacts with organic substances to generate alkylantimony. Gas processing becomes difficult.

The difference in temperature between the portion (barrel etc.) where the rotary kneader and the styrene resin composition come into contact and the styrene resin composition is closer to the rotary kneader side near the inlet of the rotary kneader. The temperature of the resin composition is considerably high, and as the kneading progresses, the temperature of the resin composition rises, the temperature difference with the rotary kneader decreases, and depending on the kneading conditions, heat is generated, and the temperature of the resin composition is higher than that of the rotary kneader. May be higher than the temperature. The degree of pressure reduction at this time is preferably 13.3 kPa or less,
Preferably 6.67 kPa, more preferably 1.33 kPa
Pa is good.

The thus treated molten resin component becomes waxy and contains almost no halogen and antimony. Therefore, after cooling, it may be solidified as a solid fuel or further oilified. The generated gas of the present invention includes hydrogen bromide and antimony tribromide. For this, an aqueous solution of sodium hydroxide or an equivalent aqueous solution may be cooled well and sprayed, or may be passed through a washing tower (scrubber).
At this time, the pH after the treatment needs to be adjusted to 7 to 13.
If the pH is exceeded, antimony starts to dissolve in the aqueous solution as an antimonate, and if the pH is lower than that, undesired antimony oxobromide is dissolved in the aqueous solution. When the treatment liquid is separated by filtration, diantimony trioxide and an aqueous solution of NaBr are recovered. The purity of diantimony trioxide at this time is 90 w
t% or more.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Implementation Process FIG. 1 shows a process used to implement the invention. A twin screw extruder is installed in front of the rotary kneader to knead the TV casing waste and the treatment agent well before reacting. In order to improve the kneading of the waste and the treating agent, the pressure at the tip of the extruder should be 100 to 1
Keep at 20 atm. Next, the molten resin is sent to the horizontal continuous kneader through the orifice tube, and degassing is performed at a stretch. The degree of pressure reduction at this time was 1.33 k to 8.68 kPa. The processing time here was set to be paid out within 5 minutes. The generated gas is drawn directly by a corrosion-resistant ceramic vacuum pump, and the exhaust line is connected to the washing tower. An aqueous sodium hydroxide solution is sprayed from the upper stage of the washing tower to react the gas, and antimony tribromide and hydrogen bromide are excluded. At this time, the pH of the collected washing liquid was adjusted to fall within the range of 7 to 12. The recovered washing liquid is sent to a continuous filtration device in a white suspended state, and diantimony trioxide and a NaBr solution are separated. Antimony trioxide is dried to become crude antimony, and NaBr is obtained by evaporating water.

(2) Analysis of Halogen and Antimony In the analysis of halogen, a sample was burned under pure oxygen in a combustion flask, this gas was absorbed in water stretched over a non-burning flask, and a mixed solution of acetic acid and sodium acetate was added. After the addition, a bromine ion meter (manufactured by Toa Denpa Co., Ltd., IN55S) is used, and antimony is measured by an IPA method (plasma ion analysis method).

(3) Preparation of Model Waste Model waste is commercially available HIPS, for example, A & M Polystyrene H8117 (melt flow ISO R).
1133 200 ° C. with 5 kg load, 1.7 g every 10 minutes,
Flexural modulus 1860 MPa according to ASTM D790) /
Decabromodiphenyl ether (manufactured by Tosoh Corporation) / dantimony trioxide (manufactured by Yamanaka Sangyo Co., Ltd.) is 80 / weight ratio.
One mixed at a ratio of 20/5 is used. As a polypropylene used as the polyolefin, J-ALOMER PM600A (trade name, manufactured by Nippon Polyolefin Co., Ltd., 40 g per 10 minutes with a melt ISO R1133) was used. A mixture obtained by mixing the pellets in 1/1 parts by weight is used.

(4) Measurement of Shear Viscosity of Resin The shear viscosity of the resin was measured for its shear rate and temperature dependency by a twin capillary rheometer manufactured by Lausand. The temperature range at this time is up to 140-300 ° C and 100-
Temperatures up to 140 ° C. were calculated based on the WLF equation. It is to be noted that at a resin temperature of 100 ° C. or lower, the resin is ignored because it does not melt. Hereinafter, Examples and Comparative Examples will be described.

[0032]

Examples 1 to 5, Comparative Examples 1 and 2

[0033]

[Table 1]

[0034]

According to the present invention, a method for removing and recovering bromine and antimony in resin waste in a short time and in a high yield, and enabling the treated resin to be used as a solidified fuel. Can be provided.

[Brief description of the drawings]

FIG. 1 shows a cross section of a rotary kneader.

FIG. 2 shows the steps used in this study.

FIG. 3 shows an example of a screw configuration of a rotary kneader.

[Explanation of symbols]

 1 Shows the apex angle α of the screw element 2 Shows the side opening angle β 3 Shows the resin pool angle θ 4 Shows the resin pool 5 Shows the fixed-quantity feeder that sends waste / treatment agent 2 Shows the preheating kneading extruder 3 Connecting orifice Shows a tube 4 Shows a horizontal rotary kneader 5 Shows a preheating extruder 6 Shows a corrosion-resistant vacuum pump 7 Shows a gear pump 8 Shows an outlet of treated resin 9 Shows a washing tower (scrubber) 10 Shows an inlet of a washing liquid 11 Shows the washing liquid sprayer 12 Shows the outlet of the treated gas 13 Shows the filter 14 Shows the outlet of the filtered water 15 Shows the recovered diantimony trioxide 16 Shows the resin inlet 17 Shows the treated resin outlet 18 19 shows screw element (1) 19 shows screw element (2) 20 screw element (3) Shows the 22 screw element (5) showing the 21 screw element (4) showing

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Claims (7)

[Claims] 1. A method for continuously separating and recovering bromine and antimony from a styrenic resin composition containing a bromine-based flame retardant and an antimony compound by using a device having a rotary stirring function. The effective treated surface area is 5 m ^{2 to} 100 m ² and the temperature of the styrene resin composition is 280
To 370 ° C. 2. The value of the specific energy applied to the resin waste treated by the apparatus having the rotary stirring function until the resin temperature reaches 300 ° C. is 10 MJ / m ^{3 to} 300 MJ /
The method according to claim 1, characterized in that the m ^3. 3. The method according to claim 1, wherein the polyolefin-based treating agent is added to the styrene-based resin composition in an amount of 20 to 70% by weight. 4. The apparatus having a rotary stirring function has a pressure reduction degree of 13.3 kPa or less.
The method according to claim 3. 5. A solid fuel having a bromine content of 2% by weight or less, obtained by the method according to claim 1. 6. A method of reacting a gas generated by the method of claim 1 with an aqueous alkaline solution to extract diantimony trioxide from the styrene resin composition within a pH range of 12 to 7. 7. Antiantimony trioxide obtained by the method according to claim 1.