JPH08333473A - Method for recovering noncross-linked synthetic resin waste using solvent composition - Google Patents

Abstract

PURPOSE: To provide an environmentally friendly method for recovering a noncross-linked synthetic resin waste by using a solvent compsn. contg. at least one compd. selected from among a specific acetic ester, a specific ketone, and a specific cyclic ketone as the effective component. CONSTITUTION: In this method, a noncross-linked synthetic resin waste is dissolved in a solvent compsn. contg. as the effective component at least one compd. selected from among an acetic ester represented by formula I (wherein R<1> is a 4-8C alkyl or cycloalkyl provided at least one H atom of R<1> may be substd. by a group having at least one either, ester, or hydroxyl group), a 9-6C ketone represented by formula II (wherein R<2> and R<3> are each a 1-77C alkyl or phenyl provided H atoms of the alkyl group may be substd. in the same way as in the compd. of the formula I), and a 6-9C cyclic ketone represented by formula II (wherein R<4> and R<5> are each H or a 1-3C alkyl).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering non-crosslinked synthetic resin waste, especially styrene resin waste, which is characterized by using a solvent composition.

[0002]

BACKGROUND OF THE INVENTION Synthetic resins are used not only as molded products but also widely as containers, packaging or packing materials for various articles including food and clothing.

Therefore, when a certain type of product is manufactured, various plastic wastes are generated from the manufacturing plant, the distribution system, the user, and the like. To meet the user's strong demand,
In today's world where many kinds of products are manufactured, plastic waste is inevitable everywhere.

[0004] These plastic wastes are increasing as industrial wastes and general wastes, and an efficient recovery method or disposal method is important for manufacturers, distributors, and local governments. It is a well-known fact that it is a serious problem.

The same can be said for foams such as foam styrol. Conventionally, foamed styrol is widely used in food trays and the like because it has excellent properties such as light weight, compressive strength and moldability, but the foamed styrol is stable and does not rot, In addition, since it is bulky, efficient collection methods and waste disposal have become important problems.

Currently, most industrial waste is buried underground or otherwise disposed of by waste disposers, while municipal waste is incinerated at municipal waste disposal sites, or It is buried in the ground.

In any case, plastic waste is a pollution source of air and groundwater, and its disposal causes environmental pollution. As a means for solving these problems, a method of dissolving plastic waste in a hydrocarbon solvent and collecting it has been proposed (JP-A-51-28175, etc.). However, in this method, the solvent used is deleterious substances, carcinogenicity, aromatic hydrocarbons such as xylene, benzene, carbon tetrachloride, etc. or halogenated hydrocarbons, which may cause environmental damage. Not desirable for security. Also, a method using limonene has been proposed recently, but the dissolution rate of plastic waste is slow, which is a problem from the viewpoint of workability.

[0008]

As described above, in the technical field of the present invention, there is no toxicity or safety problem to human body, no fear of environmental damage, and a recovery solvent having a high dissolving power for waste plastic. Development has become an important issue.

The present invention overcomes the drawbacks of the conventional aromatic hydrocarbons and halogenated hydrocarbons as described above, is composed of a non-halogen solvent, does not generate environmentally destructive substances, and has the ability to dissolve plastic waste. The objective of the present invention is to provide a method for recovering plastic waste using a safe solvent composition that is highly stable, has no toxicity or unpleasant odor, has high biodegradability, does not accumulate in nature, and has a relatively high boiling point. It is what

[0010]

The inventors of the present invention have conducted extensive studies to develop a plastic waste recovery method using a solvent composition having the above-mentioned preferable properties, and as a result, the solvent composition used in this recovery method has been developed. As a product, an acetic acid alkyl ester and a compound containing a specific ketone group were found to meet the purpose, and the present invention was accomplished.

That is, the present invention provides an acetic acid alkyl ester represented by the following general formula [1].

Embedded image CH ₃ CO ₂ R ¹ [1] (R ¹ in the formula represents an alkyl group having 4 to 8 carbon atoms or a cycloalkyl group. One or more atoms may be substituted with a substituent containing any one or more of an ether group, an ester group and a hydroxyl group.) The total number of carbon atoms represented by the following general formula [2] is 6 or more 9
Or less ketone group-containing compound

Embedded image R ² COR ³ ... [2] (In the formula, R ² and R ³ represent an alkyl group having 1 to 7 carbon atoms or a phenyl group. 1 or 2 or more may be substituted with a substituent containing any 1 or 2 or more of an ether group, an ester group or a hydroxyl group.) And a total carbon number represented by the following general formula [3] is 6 And 9 or less ketone group-containing cyclic compound

[Chemical 6] (R ⁴ and R ⁵ in the formula represent hydrogen or an alkyl group having 1 to 3 carbon atoms.) A non-crosslinked synthetic resin waste is dissolved in a solvent composition containing at least one compound selected from And a method for recovering non-crosslinked synthetic resin waste.

The present invention will be described in detail below. It is important that the solvent composition used in the method for recovering the non-crosslinked synthetic resin waste of the present invention contains an alkyl acetate or a specific ketone group-containing compound.

Examples of the acetic acid alkyl ester (corresponding to the general formula [1]) include butyl acetate, isobutyl acetate and acetic acid-1.
-Methylpropyl, amyl acetate, isoamyl acetate, hexyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, 2-ethylhexyl acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, propylene glycol butyl ether acetate, propylene Glycol diacetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate, dipropylene glycol monoacetate, dipropylene glycol diacetate, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, diethylene Recall ether acetate, 3-methoxy-3-methyl-butyl acetate,
3-methoxybutylacetate and the like can be mentioned, particularly butyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate, propylene glycol methyl ether acetate,
3-methoxy-3-methylbutyl acetate or 3-
Methoxybutylacetate is preferred from the standpoint of solubility and volatility.

Examples of the ketone group-containing compound (corresponding to the general formula [2]) include acetophenone, ethyl normal butyl ketone, 4-hydroxy-4-methyl-2-pentanone, diisobutyl ketone, dipropyl ketone, diisopropyl ketone and methylbutyl. Ketone, methyl isobutyl ketone, methyl amyl ketone, methyl hexyl ketone,
Examples of the ketone group-containing cyclic compound (corresponding to the general formula [3]) such as methylheptyl ketone include cyclohexanone,
Examples thereof include methylcyclohexanone and dimethylcyclohexanone, with methylisobutylketone, methylamylketone, cyclohexanone or methylcyclohexanone being particularly preferred from the viewpoint of solubility and volatility.

These acetic acid alkyl esters (corresponding to general formula [1]), ketone group-containing compounds (corresponding to general formula [2]) and ketone group-containing cyclic compounds (corresponding to general formula [3]) are used alone. They may be used, or two or more kinds may be used in combination. The mixing ratio is arbitrary.

The acetic acid alkyl ester, the ketone group-containing linear compound and the ketone group-containing cyclic compound in the present invention are well compatible with other general organic solvents such as alcohols, esters, ketones, amides, aromatics, etc. Natural resin such as, styrene resin, acrylic resin,
It has extremely excellent solubility in a wide range of high molecular compounds such as vinyl resins such as vinyl acetate resins and vinyl chloride resins, synthetic resins such as polyester resins and polyamide resins. Therefore, the alkyl acetate, the ketone group-containing compound and the ketone group-containing cyclic compound used in the recovery method of the present invention can be used alone as a solvent, but are also used as a solvent composition in which other organic solvents are used in combination. You can also do it. The ratio is arbitrary, but in order to effectively develop the solubility of the alkyl acetate, the ketone group-containing compound or the ketone group-containing cyclic compound, these compounds are contained in an amount of 5% by weight or more, preferably 10% by weight or more. It is good to say

The organic solvent used in combination is not particularly limited, but preferred examples are methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, dimethylformamide, dimethylacetamide, methyl acetate, ethyl acetate, methyl lactate, lactic acid. Ethyl, Butyl lactate, Methyl β-methoxypropionate, β
-Ethyl ethoxypropionate, toluene, xylene,
Hexane and the like can be mentioned. These organic solvents can be used in combination of two or more kinds.

As the resin to be used in the present invention, styrene synthetic resin, polyester resin and acrylic resin are particularly preferable. The styrene content in that case is not particularly limited, but is preferably 5% or more, particularly preferably 1%.
It is 0% or more. Further, as the styrene synthetic resin,
Essentially any styrene-based resin can be used, and it is a styrene-modified composite foamed resin that is used as a cushioning material for packing materials, car bumper-filling materials, etc. due to its moldability, compressive strength, and high shock absorption. Examples thereof include ABS resin and AS resin used as a casing material, and expanded polystyrene discharged as ordinary household waste, but polystyrene and expanded polystyrene are particularly preferable.

The shape of the styrene-based synthetic resin to which the present invention is applied may be any of a film, a sheet, a foam and a molded product.

The synthetic resin solution after recovery can be reused as it is as a resin solution. In addition, after recovering the solvent by devolatilization under reduced pressure, the resin is recovered as pellets,
It can be reused.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 The temperature of the jacket 4 of the dissolving tank 3 having an effective internal volume of 20 liters shown in FIG. 1 was set to 100 ° C. in advance. 5.8 Kg of polystyrene waste was fed to the grinder 1, then the ground polystyrene waste was fed to the dissolution tank 3 by the air pressure of the blower 2, and 10 Kg of butyl acetate was fed with stirring to give about 20 In minutes a polystyrene solution formed.

The polystyrene solution thus obtained was filtered 11
After removing the insoluble foreign matter from the solution, the diameter of 15c preset to the temperature of 230 ° C and the vacuum degree of 30 Torr.
It was supplied to a vacuum devolatilization tank 5 having a height of 100 m and a height of 100 cm for about 3 hours. The obtained polystyrene melt was extracted from the devolatilization tank 5, supplied to the die 7 through the double conduit 6 and extruded from the nozzle, and a string-shaped molded product having extremely excellent transparency was obtained. When this string-shaped molded product was cut with a cutter 8 and pelletized, about 5.6 kg of polystyrene pellets, which were almost colorless and similar to virgin, were obtained.

The evaporated solvent was used as a condensate in the condenser 9 and sent to the solvent tank 10 to be reused as a solvent.

Examples 2 to 8 Implementation was carried out except that isoamyl acetate, propylene glycol methyl ether acetate, 3-methoxy-3-methylbutyl acetate, 3-methoxybutyl acetate, methyl isobutyl ketone, methyl amyl ketone and cyclohexanone were used as the solvent. The procedure was as in Example 1.

[0026]

Example 9 Example 1 was repeated except that ABS resin was used as the plastic waste.

Example 10 Example 10 was repeated except that methyl isobutyl ketone was used as the solvent and ABS resin was used as the plastic waste.

Comparative Examples 1 to 3 Example 1 was repeated except that xylene, acetone or limonene was used as the solvent.

The results of Examples 1 to 10 are shown in Table 1, and the results of Comparative Examples 1 to 3 are shown in Table 2.

[Table 1]

[0030]

[Table 2] In the table, polystyrene resin: QP-2B (manufactured by Denka) ABS resin: Diapet 1001 (manufactured by Mitsubishi Rayon)

[0031]

EFFECTS OF THE INVENTION According to the present invention, a general-purpose styrene-based synthetic resin that is stable, does not decompose and is bulky (foam styrene, etc.) can be efficiently recovered by dissolving it in a solvent. Further, the solvent used has the following advantages. 1) It does not damage the environment because it does not contain halogen atoms. 2) It is safe in terms of working environment because it has no toxicity or unpleasant odor. 3) Due to its high biodegradability, it does not accumulate in the natural world. 4) Boiling point and flash point are relatively high, and operability and safety are remarkably improved. 5) Mix freely with many organic solvents.

[Brief description of drawings]

FIG. 1 is a schematic flow sheet for carrying out a method for recovering a styrene-based synthetic resin according to the present invention.

[Explanation of symbols]

 1 Crusher 2 Blower 3 Melting tank 4 Jacket 5 Vacuum devolatilization tank 6 Double conduit 7 Die 8 Cutter 9 Condenser 10 Solvent tank 11 Filter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // B29K 101: 00 105: 26

Claims (3)

[Claims] 1. An acetic acid alkyl ester represented by the following general formula [1]: embedded image CH ₃ CO ₂ R ¹ ... [1] (wherein R ¹ has 4 to 8 carbon atoms). Represents an alkyl group or a cycloalkyl group, provided that one or more hydrogen atoms in these alkyl groups are substituted with a substituent containing any one or more ether group, ester group or hydroxyl group. However, the total carbon number represented by the following general formula [2] is 6 or more 9
No more than 3 ketone group-containing compounds R ² COR ³ ... [2] (In the formula, R ² and R ³ represent an alkyl group having 1 to 7 carbon atoms or a phenyl group. 1 or 2 or more of the hydrogen atoms in the alkyl group may be substituted with a substituent containing any 1 or 2 or more of an ether group, an ester group or a hydroxyl group.) And the following general formula [3] Ketone group-containing cyclic compound represented by total carbon number of 6 or more and 9 or less (R ⁴ and R ⁵ in the formula represent hydrogen or an alkyl group having 1 to 3 carbon atoms.) A non-crosslinked synthetic resin waste is dissolved in a solvent composition containing at least one compound selected from A method for recovering non-crosslinked synthetic resin waste, comprising: 2. An acetic acid alkyl ester or ketone group-containing compound is butyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate, propylene glycol methyl ether acetate, 3-methoxy-3-methylbutyl acetate, 3-methoxybutyl acetate, methyl isobutyl ketone. The method for recovering non-crosslinked synthetic resin waste according to claim 1, which is methyl amyl ketone, cyclohexanone or methylcyclohexanone. 3. The solvent composition comprises at least one acetic acid alkyl ester or ketone group-containing compound and methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, dimethylformamide, dimethylacetamide, methyl acetate, ethyl acetate, methyl lactate, lactic acid. The non-crosslinked synthetic resin waste according to claim 1, further comprising at least one compound selected from the group consisting of ethyl, butyl lactate, methyl β-methoxypropionate, ethyl β-ethoxypropionate, toluene, xylene and hexane. Recovery method.