JP2000256502A - Processing liquid for foamed polystyrene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid for processing foamed polystyrene preventing thermal decomposition and oxidation caused from hydrolysis of an organic solvent as much as possible, free from corrosion of processing equipment capable of instantaneously reducing volume of the foamed polystyrene by including an epoxide and amine compound in methylenechloride. SOLUTION: The liquid preferably comprises (A) 99.2-99.7 wt.% of methylene chloride, (B) 0.2-0.5 wt. % of an epoxide such as propylene oxide or the like and (C) 0.01-0.05 wt.% of an amine compound such as diisopropylamine or the like. The liquid preferably comprises a 5-7C unsaturated hydrocarbon such as 2-pentene or the like and a 1-3C alcohol such as methanol or the like. Preferably, the amount of the above unsaturated hydrocarbon is 50-100 ppm and that of the alcohol is 500-1000 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrofoam treatment solution which is capable of instantaneously reducing the volume of styrofoam used in a packing material or the like and which is excellent in environmental aspects.

[0002]

2. Description of the Related Art Styrofoam is excellent in cushioning property, impact resistance, water resistance and heat insulation, and is easily processed into an arbitrary shape and is inexpensive. It is used in a wide range of fields, such as timber and fresh food trays.

[0003] However, since styrofoam has a bulky property, a large space is required for disposal.
Transport costs increase. In addition, they do not decompose in the soil, generate black smoke during incineration, and damage the incinerator due to high heat. This is a problem in terms of disposal costs and environmental protection.

[0004] On the other hand, in recent years, various regulations have been tried for recycling styrofoam since the momentum for environmental protection and resource recycling is increasing in accordance with the regulations of the Industrial Waste Disposal and Public Cleansing Law.

[0005] For example, the heat volume reduction method for melting and reducing the volume of polystyrene foam by applying heat such as electric heating or hot air heating consumes a large amount of electric energy, makes it difficult to remove foreign substances, and performs high heat treatment (280 to 300 ° C). As a result, the properties of recycled products deteriorate,
There are problems such as deterioration of the environment due to odor during treatment.

[0006] Solvent dissolving methods for dissolving polystyrene foam in an organic solvent to reduce the volume include ketones, esters, aromatic hydrocarbons, chlorine solvents, other ethers,
A method has been proposed in which styrene foam is dissolved and reduced in volume using an organic solvent such as monoterpenes, and the organic solvent and styrene resin are separated and recovered from the solution.

However, ketones, esters, ethers, aromatic hydrocarbons and the like, excluding chlorine-based solvents, are dangerous because they are all flammable solvents. Further, when styrene foam is dissolved in an organic solvent and made into a solution, the water introduced by the styrene foam, the moisture in the atmosphere, and the oxygen in the air are contained in this solution. Therefore, the organic solvent and the styrene foam resin are separated and recovered from this solution. Therefore, treatment such as heat distillation is indispensable. Here, the problem is oxidation due to thermal decomposition and hydrolysis of the organic solvent. Furthermore, in order to solve these problems, it is necessary to consider filling and mixing of an inert gas.

As described above, it has been desired to develop a stable styrofoam treatment solution while preventing the organic solvent from being thermally decomposed and oxidized by hydrolysis, but there has been no satisfactory solution.

Therefore, the present invention can prevent oxidation of the organic solvent by thermal decomposition and hydrolysis as much as possible, and can instantaneously reduce the volume of polystyrene foam without corroding the treatment equipment.
An object of the present invention is to provide a styrofoam treatment liquid that is excellent also in terms of stability.

[0010]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, used methylene chloride as an organic solvent, and added an epoxide and an amine compound thereto. The added processing liquid, more preferably the processing liquid further added with an unsaturated hydrocarbon having 5 to 7 carbon atoms or an alcohol having 1 to 3 carbon atoms, instantaneously reduces the volume of styrene foam, and in this case, The present invention has been found to prevent oxidation due to thermal decomposition and hydrolysis of an organic solvent (methylene chloride), to be stable and to be excellent from the viewpoint of environmental protection, and to accomplish the present invention.

Hereinafter, the present invention will be described in more detail.
The styrofoam treatment liquid of the present invention contains methylene chloride, epoxide, and an amine compound.

Here, the content of methylene chloride in the treatment liquid is 98.5 to 99.9% (weight%, the same applies hereinafter), particularly 9
It is preferably from 9.2 to 99.7%. If the amount of methylene chloride is too small, the added amount of the epoxide, the amine compound, etc. increases, and there may be flammability.If the amount is too large, the added amount of the epoxide, the amine compound, etc. decreases, so that the stability of the methylene chloride decreases. And may induce thermal decomposition and hydrolysis.

The epoxide used in the present invention is preferably an epoxide having a boiling point of from 30 to 90 ° C., and specific examples thereof include propylene oxide, butylene oxide and tetrahydrofuran. The epoxide can be added alone or in combination of two or more thereof.
0%, preferably 0.2 to 0.5%. If the amount of the epoxide is too small, the stabilization of methylene chloride cannot be maintained, and if the amount is too large, a by-product is easily generated.

As the amine compound used in the present invention, an amine compound having a boiling point of from 30 to 90 ° C. is preferred, and specific examples thereof include diethylamine, triethylamine, isopropylamine, diisopropylamine, n-butylamine and the like. No. The amine compound can be added alone or in combination of two or more thereof, and the amount of addition is 0.01 to 0.2%, preferably 0.01 to 0.05%. If the amount of the amine compound is too small, the stability of heat and hydrolysis cannot be maintained, and if it is too large, the action of eroding methylene chloride may be increased.

The styrofoam solution of the present invention may further contain an unsaturated hydrocarbon having 5 to 7 carbon atoms.
Specific examples of the unsaturated hydrocarbon having 5 to 7 carbon atoms include 2-pentene, 2-methyl-2-butene, 2-hexene, and 2-heptene. The unsaturated hydrocarbon having 5 to 7 carbon atoms can be added alone or in combination of two or more thereof.
pm, preferably 50-100 ppm. Carbon number 5
If the amount of the unsaturated hydrocarbons of (7) to (7) is less than 10 ppm, it does not contribute to the effect of suppressing the decomposition of methylene chloride.

The styrofoam treatment solution of the present invention comprises:
Further, an alcohol having 1 to 3 carbon atoms can be added. Specific examples of the alcohol having 1 to 3 carbon atoms include methanol, ethanol, propanol, and isopropyl alcohol. The alcohol having 1 to 3 carbon atoms can be added alone or in combination of two or more thereof, and the added amount is 10 to 2000 ppm,
Preferably it is 500-1000 ppm. Carbon number 1
If the addition amount of the alcohol 3 is less than 10 ppm, it does not contribute to the effect of suppressing the decomposition of methylene chloride, and if it exceeds 2000 ppm, the effect of suppressing the decomposition of methylene chloride cannot be expected, and the flammability is increased.

As a method for treating used styrofoam using the styrofoam treatment solution of the present invention, a method similar to a conventionally known solvent dissolving method can be employed, but the dissolving temperature is preferably 20 to 30 ° C. preferable.

Further, from the treatment liquid after the treatment of the expanded polystyrene, methylene chloride can be recovered by heating distillation, and the polystyrene from which methylene chloride has been separated and removed can be recycled by an ordinary method. in this case,
The processing liquid of the present invention suppresses thermal decomposition and hydrolysis of methylene chloride even when moisture is mixed in the processing liquid during heating distillation, and also suppresses damage to processing equipment such as stainless steel.

[0019]

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

[Examples and Comparative Examples] (1) Hydrolysis of Styrofoam Treatment Solution Styrofoam treatment solution 400 having the composition shown in Tables 1 and 2
autoclave (volume 1L, SUS)
316), and after sealing, the temperature was raised to a set temperature of 160 ° C. (internal pressure of 2.5 MPa), and this state was maintained for 2 hours. Then, back to room temperature and quenched, pH of water, Cl ^- was determined of emissions.

The pH of the styrofoam treatment liquid aqueous layer, Cl ^-
Of the methylene chloride, which is the main component of the styrofoam treatment liquid of the present invention, and the degree of damage to the processing apparatus material by the styrofoam treatment liquid were evaluated based on the presence or absence of water layer coloring and corrosion of the autoclave material. The results are shown in Tables 1 and 2.

[0022]

[Table 1]

[0023]

[Table 2]

(2) Volume Reduction by Styrofoam Treatment Solution In a 300 mL tall beaker, 100 mL of each of the Styrofoam treatment solutions having the same composition as in Example 2 were added, and 500 mL
(4 × 4.2 × 30 cm) styrene foam test piece
Each piece was immersed in each treatment liquid at room temperature (20 ° C.), and the time required for reducing the volume of the styrene foam was measured. As a comparative example, the time required for reducing the volume of styrofoam was similarly measured using ethyl acetate (Comparative Example 6) and (R) -limonene (Comparative Example 7).

In any of the styrofoam treatment liquids of Examples and Comparative Examples, when the styrofoam was sequentially dissolved, the dissolved concentration of the styrofoam resin and the viscosity of the treatment liquid were increased, and the dissolution rate of the styrofoam was slowed accordingly. .

[0026]

[Table 3]

[0027]

By using the styrofoam treatment liquid of the present invention, the volume can be reduced more instantaneously than the conventional styrofoam treatment liquid, and the efficiency of the styrofoam waste disposal work can be expected to be improved. Further, since low-boiling methylene chloride is used as a nonflammable solvent, the risk of fire and explosion is reduced, and the energy for solvent recovery can be saved.

Claims (3)

[Claims] 1. A styrofoam treatment solution comprising methylene chloride, an epoxide, and an amine compound. 2. The styrofoam treatment liquid according to claim 1, further comprising an unsaturated hydrocarbon having 5 to 7 carbon atoms. 3. The styrofoam treatment liquid according to claim 1, further comprising an alcohol having 1 to 3 carbon atoms.