JPH06226743A - Classification and recovery of plastics and device used for the same - Google Patents

Abstract

PURPOSE:To certainly classify and recover specific plastic by performing a process classifying and recovering specific plastic from a system wherein various plastics are mixed. CONSTITUTION:When stones, iron pieces and wood pieces are manually removed from a mixed system, an ETFE film is charged in an aqueous soln. (density; 133g/cm<2>) containing of iron sulfate (inorg. salt) 30% and a surfactant 0.2% and washed by an ultrasonic washing machine without generating foam. Herein, iron pieces or small stones incapable of removed manually and having density larger than the aqueous soln. are settled and removed and a string or PVC low in density is removed by flotation. The strength of the washing machine is controlled so that the ETFE film is convected to the intermediate tank of the aqueous soln. by the convection due to the washing machine. The ETFE film is transferred from the intermediate tank where ETFE film is present in much quantity to a classifying tank and the fine iron pieces, a stone powder and the like incapable of being removed in the washing process are settled and removed and PVC or strings are removed by flotation. The classified ETFE film is washed and dried.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and recovering plastics and an apparatus used therefor, and more specifically, a method for separating and recovering specific plastics from a system in which various plastics are mixed and a method therefor. Regarding the equipment used.

[0002]

2. Description of the Related Art Conventionally, various techniques have been used for separating and collecting plastics. For example, a sieve,
The technologies such as wind power, magnetism, eddy current, static electricity, magnetic field, solvent and elasticity were used alone or in combination of two or more.

However, for example, when sorting and collecting used plastic covering materials in a greenhouse for facility gardening, plastics such as vinyl chloride resin, polyethylene, vinyl acetate resin, fluorine-containing resin and polyethylene, covering Metals such as bolts, nuts, screws, and fixing members that fix materials, as well as dirt, dirt, moss, iron rust, oils and fats that adhere to the covering material, and efficiently separate specific plastics, To collect is
I could hardly do it.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the prior art, that is, a specific plastic from a system in which various plastics are mixed. The present invention provides a method for fractionating and recovering, wherein the step of fractionating and recovering is mainly through a high-concentration aqueous solution of an inorganic salt.

According to the present invention, however, plastics such as vinyl chloride resin, polyethylene, vinyl acetate resin, fluorine-containing resin and polyethylene, and metal such as bolts, nuts, screws and fixing members for fixing the covering material. It is possible to efficiently sort and collect specific plastics from the foreign substances such as soil, moss and iron rust attached to the coating materials. The constituent factors of the present invention will be described in more detail below.

In the present invention, the "plastics" are not particularly limited and may be any plastics film, for example, vinyl resin, styrene resin, polyethylene resin, polyacetal resin,
Acrylic resins, polyamide resins, cellulose resins, polycarbonate resins, polyester resins, polyurethane resins, fluorine-containing resins and engineering plastics (engineering plastics), among others, vinyl resins, styrene resins, polyacetals. Resins, cellulose resins, polyester resins, fluorine-containing resins and engineering plastics are preferable, fluorine-containing resins and engineering plastics are more preferable, and fluorine-containing resins are particularly preferable.

Here, the vinyl resin is, for example, vinyl chloride (PVC), polyvinyl butyral (PVB),
There are polyvinyl alcohol (PVA), polyvinylidene chloride (PVdC), polyvinyl acetate (PVAc), polyvinyl formal, polyvinyl dichloride, and the like. Among them,
PVC and PVAc are preferred.

Examples of the styrene resin include polystyrene, styrene-acrylonitrile copolymer (A
S) and ABS resin and the like, and examples of the polyethylene resin include polyethylene (PE), ethylene / vinyl acetate copolymer (EVA), polypropylene and the like.

Further, the acrylic resin is, for example, polymethylmethacrylate (PMMA) and polyacrylate (PMA) and the like, and polyamide resin nylon 6, nylon 66, nylon 610 and nylon 1 are used.
It is 1 mag. Examples of the cellulosic resin include ethyl cellulose (EC), cellulose acetate (CA), propyl cellulose (CP), acetic acid / butyrate cellulose (CA).
B) and cellulose nitrate (CN), etc., among which CA
B is preferred.

Examples of polyester resins include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), among which PET is preferred.

The fluorine-containing resin is a general term for synthetic resins obtained by polymerizing olefins containing fluorine. Specifically, for example, polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene-based copolymer (PCTFE), hexafluoropropylene-tetrafluoroethylene-based copolymer (FEP),
Perfluoroalkyl vinyl ether-tetrafluoroethylene copolymer (PFA), perfluoroalkyl vinyl ether-hexafluoropropylene-tetrafluoroethylene copolymer (EPE), polyvinylidene fluoride (PVdF), polyvinyl fluoride (PVF), etc. In the present invention, any of these can be used, but among them, ETFE, PVdF, PVF and PFA are preferable, and ETFE is more preferably used.

The ETFE will now be described in more detail. The ETFE is mainly composed of ethylene and tetrafluoroethylene (the molar ratio of ethylene / tetrafluoroethylene is generally 40/60 to 60/40), and if necessary, A small amount (usually 10 mol% or less) of a third comonomer component is copolymerized therewith, and in the present invention, particularly, the ethylene / tetrafluoroethylene content molar ratio is 40/60 to 60/40, preferably Is 45 / 55-5
A perfluoroalkylvinyl monomer unit of the formula CH ₂ ═CH—C _n F _{2n + 1,} where n is an integer from 2 to 10 (eg CH ₂ = CH-C ₄ H ₉
Or an ethylene-tetrafluoroethylene-based copolymer having a content of CH ₂ ═CH—C ₆ H ₁₃ derived from 0.1 to 10 mol%, preferably 0.3 to 5 mol%. Coalescence is preferably used. This ethylene-tetrafluoroethylene-based copolymer is known per se and can be produced, for example, by the method described in JP-B-59-50163. It is also possible to use a commercially available product under the trade name of COP).

Further, engineering plastic is a general term for plastics used in places where mechanical properties such as mechanical parts and electric / electronic parts are strongly required, and specifically, polysulfone (PS) and polyether sulfone. (PE
S), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyaramid, polyarylate (PAR), polymethylpentel (PM)
P) and polyethylene naphthalate (PEN), etc., among which PI, PES, PEEK and polyaramid are preferable.

In the present invention, a specific plastic can be efficiently separated and collected from a system in which two or more kinds of the various plastics are mixed. Further, in the present invention, the “inorganic salt” is not particularly specified, and any inorganic salt may be used as long as the specific gravity of the aqueous solution can be set by adjusting the concentration in the aqueous solution. Specifically, it is possible to use the inorganic salts described in "Chemical Handbook Basic Edition, Revised Edition" edited by The Chemical Society of Japan (published by Maruzen Co., Ltd., June 25, 1981), pages II-7-11. Of these, halides, sulfates, carbonates and nitrates are preferable, and halides and sulfates are particularly preferable.

The halide includes chlorine, bromine, iodine and the like, and chlorine is preferable among them.

The metal element used in the inorganic salt includes, for example, Group I such as Li, Na, K and Ag, Mg, Ca, Ba and
Group II such as Zn, Group IV such as Ge and Sn, and Fe, Co, Ni
Group VIII, such as Group II, Group IV and Group VIII
Groups are preferred, especially Groups IV and VIII.

Among the elements of Group II, Ca and Zn are preferable, Sn is preferable as Group IV, and Fe is suitably used as Group VIII element. Specific examples of the above chlorides include CaCl ₂ , CdCl ₂ , CuCl ₂ , BaCl ₂ , FeCl ₃ , and MgC.
There are l ₂ , MgCl ₂ , SrCl ₂ , SnCl ₂ , SnCl ₄ , ZnCl _{2 and the} like, among which SnCl ₂ and ZnCl ₂ are preferable.

Specific examples of the sulfate include CuSO ₄ , MgS
O ₄ , Fe ₂ (SO ₄ ) ₃ , Na ₂ SO ₄ , (NH ₄ ) ₂ SO ₄ , Rb ₂ SO ₄ , and ZnSO
There are ₄ such among them Fe ₂ (SO _{4) 3} is preferred, as the _{carbonate, K 2 CO 3, KHCO 3} , Na 2 CO 3, there is NaHCO _3, etc. Among them, K ₂ CO
₃ is preferred.

The density (g / cm ³ ) of these aqueous solutions can be appropriately selected according to the specific gravity of the plastics to be separated and collected and the type of plastics present in the system. For example, if the plastic is ETFE and it is separated and collected from a system composed of soft PVC (P-PVC), PE, PVAc, sand, iron powder (pieces), etc., Fe ₂ (SO ₄ )
_{3 If} the concentration of Fe ₂ (SO ₄ ) _{3 in} the aqueous solution is 14 wt% or more, the density of the aqueous solution will be 1.14 g / cm ² or more, so P-PV
C, PE and PVAc float easily, sand and iron powder immediately precipitate, and the target ETFE has a specific gravity of 1.
Since it is 73 and precipitates at a slow rate, ETFE can be selectively fractionated and recovered by giving a slight flow to this system (Fig. 1).

As described above, the inorganic salt and its concentration can be appropriately determined depending on the mixed plastics and the plastics to be separated and collected. Table 1 shows the relationship between the inorganic salt composition of the aqueous solution and the specific gravity of the aqueous solution.

[0021]

[Table 1]

If the fractionation and recovery cannot be performed in a single step, the fractionation step can be added by changing the type or addition amount of the inorganic salt. further,
It is desirable to add a surfactant that is difficult to foam to the above aqueous solution. With this surfactant, foreign substances such as soil, sand, moss, iron rust, and oil and fat attached to the plastics can be removed and washed.

These surfactants are not particularly limited as long as they have a detergency and do not react with the above-mentioned inorganic salts, but they are anionic surfactants and cationic surfactants. Agents and nonionic surfactants can be used.

Here, examples of the anionic surfactant include sodium stearate, sodium oleate,
Fatty acid salts such as sodium laurate; alkylaryl sulfonates such as sodium dodecylbenzene sulfonate and sodium lauryl diphenyl ether disulfonate; aromatic sulfonic acid condensates such as sodium salt of β-naphthalene sulfonic acid formalin condensate A metal salt of, for example, an alkyl sulfate ester salt such as sodium lauryl sulfate; for example, an alkylsulfosuccinate ester salt such as sodium monooctylsulfosuccinate, sodium dioctylsulfosuccinate, polyoxyethylene sodium laurylsulfosuccinate and derivatives thereof; Polyoxyalkylene alkyl ether sulfate salts such as sodium polyoxyethylene lauryl ether sulfate; for example, polyoxyethylene nonylphenol Ether polyoxyalkylene alkyl aryl ether sulfate ester salts such as sodium sulfate: or the like can be exemplified,

Among them, alkylaryl sulfone hydrochlorides,
Emulsifiers containing sulfate metal bases or sulfonate metal bases such as alkyl sulfate ester salts, polyoxyalkylene alkyl ether sulfate ester salts, and polyoxyalkylene alkylaryl ether sulfate ester salts are preferable, and the metal is an alkali metal such as sodium or potassium. An emulsifier containing a metal sulfate base or a metal sulfonate base is preferable. Particularly, for example, sodium lauryl diphenyl ether disulfonate, sodium salt of β-naphthalene sulfonic acid formalin condensate, etc. Alternatively, an emulsifier containing a plurality of alkali metal sulfonate bases is preferable.

Examples of the cationic surfactants include alkylamine salts such as laurylamine acetate; quaternary surfactants such as lauryltrimethylammonium chloride and alkylbenzyldimethylammonium chloride.
Examples thereof include secondary ammonium salts; for example, polyoxyethylalkylamine; and examples of the amphoteric surfactants include, for example, alkylbetaine such as laurylbetaine. Further, those in which a part of hydrogen atoms of the alkyl group of these surfactants are replaced with fluorine can also be used.

Examples of the nonionic surfactants include polyoxyalkylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyalkylenes such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether. Alkylphenol ethers; for example, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate and other sorbitan fatty acid esters; for example, polyoxyethylene sorbitan monolaurate and other polyoxyalkylene sorbitan fatty acid esters; for example, polyoxyethylene Polyoxyalkylene fatty acid esters such as monolaurate and polyoxyethylene monostearate;
For example, glycerin fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride; polyoxyethylene polypropylene block copolymers;
Etc. can be mentioned.

Further, a washing machine can be used as appropriate for the purpose of improving the washing power of the above-mentioned surfactant and for minimizing bubbles in the above-mentioned aqueous solution. An ultrasonic cleaner, for example, can be used for this purpose.

In order to carry out the separation and recovery method according to the present invention and regenerate the desired plastics, for example, the following steps can be adopted (FIG. 2).

First step: Removal of foreign matters Foreign matters such as iron pieces, wood pieces, stones, strings, etc. are removed. Second step: crushing The mixed plastics are crushed into small pieces. Third step: washing In the washing step according to the present invention, in addition to washing plastics, substances such as small iron pieces, pebbles and the like that have a greater specific gravity than the aqueous solution are precipitated to remove plastics such as PVC and PE having a low specific gravity. Ascend and separate. Fourth Step: Separation The target plastics in the separation step according to the present invention are effectively separated and collected while preventing contamination of foreign substances.
Fine iron pieces, fine stones, etc., which could not be completely separated in the washing process, are precipitated and fine contaminants such as PVC and PE are floated. Fifth step: washing with water The separated plastics are washed with water. Sixth step: Drying The plastics washed with water are dried.

Thereafter, if necessary, the separated plastics may be pelletized and used as a molding material. In this way, the obtained fractionation / collection method makes it possible to efficiently fractionate / collect plastics, which greatly contributes to the industry. Hereinafter, the present invention will be described in more detail with reference to Examples.
It goes without saying that the present invention is not limited to the examples.

[0032]

[Example] A facility gardening house (300 tsubo) that has been exhibited for 8 years
The ETFE film (manufactured by Nippon Carbide Co., Ltd., F-clean film 60μ) was removed, and ETFE was fractionated and collected according to the steps shown in FIG. Each step will be described below in order.

1. Foreign Material Removal Step Iron pieces such as stones, nails, screws, bolts, nuts, etc., strings such as car wires, wood pieces, etc. adhering to or mixed with the ETFE film were manually removed. 2. Crushing Step Next, the ETFE film was crushed by a film crusher (BO-210 manufactured by Horai Iron Works Co., Ltd.) into a size of about 10 m / m × 10 m / m.

3. Washing step The ground ETFE film was treated with 30 wt% Fe ₂ (SO ₄ ) ₃ and 0.2 wt% surfactant [Perex SS-H manufactured by Kao Corporation].
Was put into an aqueous solution (density, 1.33 g / cm ³ , 25 ° C.) consisting of ETFE while being prevented from foaming by an ultrasonic cleaner [PS-5 manufactured by Kaneda Rika Kogyo Co., Ltd.] (FIG. 1).

Here, fine iron pieces, pebbles, sand, and other foreign matter having a density higher than that of the aqueous solution, which could not be removed in the foreign matter removing step, are settled and removed at the bottom of the cleaning tank to reduce the density of PV.
C, PE, string, etc. were floated and removed on the surface of the aqueous solution. ET
The strength of the FE was adjusted so that the FE was convected to the intermediate tank of the aqueous solution by convection with an ultrasonic cleaner.

4. Separation Step The aqueous solution was introduced into the separation tank while preventing foaming from the intermediate tank portion where a large amount of ETFE was present in the cleaning tank. In the separation tank, fine iron pieces, stone powder, and the like that could not be removed in the washing step are precipitated and removed, and PVC, PE, string, etc. are floated and removed to obtain high-purity ETFE.

A flow rate of 15 to 20 cm / min is maintained in the tank, high-density foreign matter is rapidly settled and removed, low-density foreign matter is floated and discharged, and ETFE is gradually settled. It is deposited downstream from the high-density foreign material. As a result, highly pure ETFE was separated and collected (FIG. 1).

5. Washing with water and drying step The separated ETFE was washed with water and dried. 6. Pelletization Step The dried ETFE was melt-extruded with a pelletizer at about 260 ° C. and pelletized.

The ETFE pellets obtained by the above steps are almost colorless and almost no foreign matter such as iron or sand is found, and no burning such as PVC, PE and other plastics is observed. ET with extremely high purity
It turned out to be FE.

[Brief description of drawings]

FIG. 1 shows that ETFE is made of soft PVC (P-PVC), PE,
It is explanatory drawing which showed roughly the process of wash | cleaning, fractionating, and collect | recovering from the system which consists of PVAc, sand, iron powder (piece), etc.

FIG. 2 is an explanatory view schematically showing the steps of separating, collecting, and recycling target plastics.

Claims (8)

[Claims] 1. A method for separating and recovering specific plastics from a system in which various plastics are mixed, wherein the separating and recovering steps are mainly performed through a high-concentration aqueous solution of an inorganic salt. How to separate and collect. 2. The inorganic salt is one or more selected from iron sulfate [Fe ₂ (SO ₄ ) ₃ ], zinc chloride (ZnCl ₂ ) and tin chloride (SnCl ₂ ). How to separate and collect. 3. The method for fractionation and recovery according to claim 1, wherein the aqueous solution of the inorganic salt has a concentration of 5% by weight or more. 4. The method of fractionation and recovery according to claim 1, wherein the plastic is a fluorine-containing resin. 5. The fractionation according to claim 4, wherein the fluorine-containing resin is ethylene tetrafluoroethylene (ETFE).
Recovery method. 6. The method of fractionation and recovery according to claim 1, wherein the aqueous solution contains a low foaming surfactant. 7. A method for separating and recovering specific plastics from a system in which various plastics are mixed, wherein the separating and recovering step is mainly performed through a high-concentration aqueous solution of an inorganic salt. Sorting and recovery equipment. 8. The separation / collection device according to claim 7, wherein the aqueous solution is provided with an ultrasonic cleaner.