JP2006193703A - Method for recycling foamed styrene - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recycling foamed styrene by reducing the volume of the foamed styrene with incombustible liquid and taking out the styrene. <P>SOLUTION: This method for recycling the foamed styrene is provided by dissolving the foamed styrene with an incombustible halogenated hydrocarbon or a polyhydric alcohol derivative, diluting and then filtering, then adding water or an alcohol for gelatinizing the styrene to take out the styrene and then drying to obtain the styrene. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for recycling polystyrene foam.

  As a method for recycling the expanded polystyrene, there is a method of gelling with a solvent such as limonene, a mixed solution of toluene, acetone, glycol, etc., and then removing the solvent [JP 2002-322287]. However, these solvents are all flammable, and there is a risk of fire and explosion during use and storage, which is a major obstacle to practical use.

  Develop a polystyrene recycling method that uses a solvent that has no risk of fire and explosion, and has the same level of toxicity as conventional ones.

The present invention is a non-polar solvent, i.e., a solvent that does not easily dissolve in water, and is a solvent that dissolves foamed polystyrene (not including a gelling solvent), dissolves foamed polystyrene, and then contains a non-adhesive polystyrene gel containing alcohol. The basic principle is to obtain. Depending on the solvent, water may be added to obtain a non-adhesive gel. There are many dihydric alcohol derivatives. A non-adhesive gel can be obtained by adding styrene foam to a solution obtained by adding 5 to 50% alcohol to the solution. This is also included in the present invention.
In the present invention, a solution that is non-toxic and difficult to ignite has been found, which will be described.
The inventor said that non-combustible halogenated hydrocarbons or polyhydric alcohol derivatives (alkylene glycol alkyl ether or alkylene glycol monoalkyl ether acetate) rapidly dissolve expanded polystyrene, and when alcohol or water is added to the dissolved liquid, polystyrene Furthermore, it was found that this gel does not adhere because it is not sticky, and that it is easy to mechanize and automate. In addition to these, there are dibasic acid esters as the solution. Among the incombustible halogenated hydrocarbons, dichlorofluoroethane (boiling point 33 ° C.) and dichloromethane are preferred.

  A small amount of alcohol, preferably 5 to 50%, may be added to these solutions, and styrene foam may be added to dissolve or gel, and then water or alcohol may be added to precipitate as a non-adhesive gel.

  In addition to the incombustible halogenated hydrocarbon, dichloropentafluoropropane is also effective in the presence of a surfactant. Furthermore, the inventor has found that diethylene glycol monoethyl ether, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, and a mixture of dichlorofluoroethane and benzyl alcohol also dissolve the expanded polystyrene. In addition to these diethylene bodies, ethylene and triethylene bodies are also dissolved. Some of these have a slow dissolution rate, but they can rapidly dissolve the polystyrene foam by heating to 40 ° C or higher, preferably 50 to 80 ° C. Examples of the same type of solution include those in which diethylene group is triethylene group, and ethyl is methyl.

  Contaminants are a problem in the recycling of polystyrene foam. In the present invention, solid impurities are filtered with a fine mesh filter or the like. In this case, it is necessary to dilute the solution to a sufficiently low viscosity so as to be suitable for filtration. The diluted solution is preferably the dissolved solution itself, but it may be mixed well with it and the polystyrene will not gel and may be hydrophobic.

  A particularly novel point in the present invention is that alcohol or water is added after the operation to precipitate dissolved styrene as a non-adhesive gel. The present invention has found a monohydric alcohol as one that precipitates dissolved polystyrene as a non-sticky gel. For example, monohydric alcohols such as methanol, ethanol, isopropyl alcohol and butanol, dihydric alcohols such as ethylene glycol, and polyhydric alcohols such as glycerin. Among them, the metal rule has the strongest precipitation force, but the precipitation force can be increased by adding a small amount of water to ethanol. In this invention, what added the water to alcohol and the main component is also contained in alcohol.

When a small amount of water is dissolved like diethylene glycol monoethyl ether acetate, only water is added in addition to the alcohol, and the dissolved styrene can be precipitated as a non-adhesive gel.
Of the solution of the present invention, all the polyhydric alcohol derivatives dissolve a small amount of water.

Alcohol is preferably added in an amount of 5 to 50% in a solution that hardly dissolves water, for example, a fluorocarbon-based solution such as dichlorofluoroethane, and when styrene foam is added thereto, the alcohol dissolves in 5 to 10%. However, if there is more alcohol, it does not dissolve and becomes a non-adhesive gel directly.
The non-adhesive gel is taken out, compressed, and dried to obtain styrene.

  When alcohol or water is added and mixed, a white gel precipitates, but excess solvent contained in the gel is removed by air drying, evaporation or reduced pressure. In the case of a high boiling polyhydric alcohol solution, steam distillation is preferred. If the solvent used has a high boiling point and is difficult to evaporate, a low boiling alcohol or a low boiling solvent may be added to the gel and mixed well, and this may be repeated and replaced to remove the high boiling solvent. This combination is preferred because most of the liquid is squeezed out when pressure is applied.

  In the step before gelation, after adding the solution to the solution in which the styrene foam is dissolved to dilute, an operation of adding water or a salt solution and shaking well may be performed. Thereby, an aqueous impurity can be removed.

  The solution can be separated by adding water and a solution in which a salt such as sodium chloride, calcium chloride, magnesium chloride or the like is added to the mixture of the solution and alcohol after separating the gel and shaking. However, alcohol can be recovered from the solution and alcohol mixture by distillation, permeation separation, or the like.

  When styrene foam was dissolved in fluorocarbon and only water or benzyl alcohol was added thereto, styrene did not precipitate, but when benzyl alcohol and water were added, styrene gel precipitated. Further, the gel was deposited even when a mixed solution of water and a water-soluble solvent such as acetone was added. Thus, the combined use of alcohols and water is useful.

  Styrofoam is dissolved in the solution of the present invention and then diluted with the solution until an appropriate viscosity is obtained. Add water or salt solution and stir well or shake. Although the liquid is separated into two phases, since the lower layer is a salt solution, solid impurities and water-soluble impurities such as pigments migrate to the lower layer. Next, the upper layer is taken out and dried or alcohol is added to separate styrene.

  Since methylene chloride and dichlorofluoroethane have a low boiling point, the above operation is preferably performed in a space cooled with tap water or the like.

According to the present invention, the current melting and recycling process can be automated. First, alcohol (preferably 5 to 30%) is mixed with a non-polar solution that is not miscible with water, and (A) Styrofoam is introduced into a container (B) containing the alcohol. There is another container (C) in which Styrofoam is charged, and the gelled liquid (A) is poured into it by the pump (D) or from above, and the foamed polystyrene is gelled. (B) or (C) has a mesh basket, and when it is pulled up, the liquid remains in (A), and the gel floating above the liquid can be taken out into the basket.
The taken-out gel is compressed by the compressor (E) to release the gelled liquid therein, and a flat soft polystyrene can be obtained. This is air dried or dried. When the cage is not used, the excess gelling solution (B) or (C) is a gel attached to the pump (D), so the hole is not easily plugged with the gel.

Reference example

  When styrene foam was added to a solution obtained by adding ethanol to dichlorofluoroethane, ethanol was 10 V / V%. In the above solution, the styrene foam became a non-adhesive gel but dissolved at 5 V / V%. Further, ethanol was increased, and 70% did not become a gel or dissolve. Methanol also had the same phenomenon at almost the same rate.

  Styrofoam fragments were added to 100 ml of dichlorofluoroethane and dissolved. Dissolution was limited to 50 g, and became a viscous product such as starch syrup. Next, 200 ml of dichlorofluoromethane was added again and stirred well to obtain a low viscosity solution. Next, 100 ml of a 30% by weight calcium chloride aqueous solution was added and shaken well, and when allowed to stand, it separated into two phases. When the lower layer was discarded and 50 ml of methyl alcohol was added to about 300 ml of the upper layer and mixed, white gel-like styrene was obtained. The gel was taken out and dried to obtain styrene. As for the mixed solution of alcohol and dichlorofluoroethane, if 100 ml of 30% by weight calcium salt solution is added and shaken well, dichlorofluoromethane is formed in the upper layer, which is reused. The lower layer recovers methanol with water / metall and separator.

  100 ml of diethyllene glycol monoethyl ether acetate was heated to 50 ° C., and 10 g of a polystyrene foam fragment was added and dissolved. Next, when 50 ml of ethanol was added and mixed, a white gel was precipitated. The gel was removed and washed with ethanol, and then a strong pressure was applied to the gel to squeeze out the liquid sufficiently. Finally, it was air-dried to obtain solid styrene. A mixed solution of ethanol and a solution can be easily separated by distillation because the boiling points of both are greatly different.

  When a liquid obtained by adding 30% ethanol to dichlorofluoroethane was put into a tank, and a foamed styrene fragment was put therein, a non-adhesive gel was obtained. The liquid in the tank was sucked out and the remaining non-adhesive gel was taken out and compressed to form a flat plate and air-dried to obtain a styrene plate.

  Styrofoam was added to diethylene glycol monoethyl ether and dissolved while stirring. Next, non-adhesive gel precipitated when water was added and stirred.

Example 5

In Run Example 3, exactly the same results were obtained with 10% methanol instead of ethanol.

Claims (8)

  A method for recycling polystyrene foam in which polystyrene foam is dissolved in a non-polar solution, alcohol or water is added thereto to obtain a polystyrene gel, or impurities are filtered, and then the contained solvent is removed to obtain polystyrene.   A foamed polystyrene recycling method in which an alcohol is mixed with a nonpolar solution for dissolving foamed polystyrene, the foamed polystyrene is made into a non-adhesive gel, and then the solvent contained in the gel is removed to obtain polystyrene.   The method for recycling polystyrene foam according to claim 1 or 2, wherein the solution is a halogenated hydrocarbon, an alkylene glycol monoalkyl ether, a dialkylene glycol monoalkyl ether acetate or a dibasic acid ester.   The solution is 1,1-dichloro1-fluoroethane, dichloropentafluoropropane, diethylene glycol monoethyl ether, diethylene glycol monohexyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate. The method for recycling polystyrene foam according to claim 3.   5. The method for recycling polystyrene foam according to claim 1, wherein pressure is applied to the obtained gel to squeeze out the solvent, and then the remaining solvent is evaporated to obtain styrene.   6. A method for recycling polystyrene foam according to claim 1, wherein water or a salt solution is added to the remaining liquid mixture of the solution and alcohol to separate and recover the solution.   The foamed polystyrene recycling method according to claim 1 or 6, wherein the foamed polystyrene is dissolved by heating the solution to 40 ° C or higher and 100 ° C or lower.   A container (B) containing a non-adhesive gelling solution (A) in which alcohol is mixed with a non-polar dissolving solution for dissolving expanded polystyrene, or an expanded polystyrene charging container (C) different from (B), and a liquid injection suction pump (D) and a compressor (E). Styrofoam is introduced into (B), or the gelled liquid (A) is injected into the container (B) into which the polystyrene is introduced using a pump (D). Then, the gel that floats above the liquid is scooped up with a net, or the gelled liquid of (B) or (C) is poured out or discarded by suction, and remains at the bottom of (B) or (C) The automated foamed polystyrene volume reduction machine that takes out the gel as it is or compresses it by the compressor (E) and re-disposes the gelled liquid contained therein and solidifies the resulting softened polystyrene.