Monomer composition for synthesizing recycled plastic, preparation method thereof, recycled plastic, and molded product using the same

Abstract

The present disclosure relates to a monomer composition for synthesizing recycled plastic that contains a high-purity aromatic diol compound recovered through recycling by chemical decomposition of a polycarbonate-based resin, a method for preparing the same, and a recycled plastic and molded product using the same.

1 . A monomer composition for synthesizing recycled plastic, comprising:
 an aromatic diol compound,   wherein a color coordinate L* of the monomer composition is more than 95,   wherein a yield of the aromatic diol compound yield-according to the following Equation 1 is 55% or more, and   wherein the monomer composition is a recovered product from a polycarbonate-based resin:
   Yield (%)=W 1 /W 0    [Equation 1]
 
   wherein in Equation 1, W 0  is a mass of the aromatic diol compound obtained during 100% decomposition, and W 1  is a mass of the aromatic diol compound actually obtained.   
     
     
         2 . The monomer composition according to  claim 1 , wherein
 the monomer composition has a color coordinate b* of 3.5 or less.   
     
     
         3 . The monomer composition according to  claim 1 , wherein
 the monomer composition has a color coordinate a* of 1 or less.   
     
     
         4 . The monomer composition according to  claim 1 , wherein
 the aromatic diol compound is one or more selected from the group consisting of bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)ketone, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy -3,5- dichlorophenyl)propane, 2,2-bis(4-hydroxy -3-bromophenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy -3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, and 1,1-bis(4-hydroxyphenyl)-1-phenylethane.   
     
     
         5 . The monomer composition according to  claim 1 , wherein
 the monomer composition has an aromatic diol compound purity of 98% or more.   
     
     
         6 . The monomer composition according to  claim 1 , further comprising:
 a diethyl carbonate as a by-product.   
     
     
         7 . A method for preparing a monomer composition for synthesizing recycled plastic, the method comprising the steps of:
 depolymerizing a polycarbonate-based resin; and   adding water of 12 times or more the weight of the polycarbonate-based resin to a depolymerization reaction product to extract an aromatic diol compound.   
     
     
         8 . The method for preparing a monomer composition according to  claim 7 , wherein
 in the step of adding water,   a number of times of adding water is 1 to 10.   
     
     
         9 . The method for preparing a monomer composition according to  claim 8 , further comprising:
 a step of removing water between the steps of adding water, when the number of times of adding water is 2 to 10.   
     
     
         10 . The method for preparing a monomer composition according to  claim 7 , wherein
 the step of adding water comprises:   repeatedly adding water of twice the weight of the polycarbonate-based resin to the depolymerization reaction product 6 to 10 times.   
     
     
         11 . The method for preparing a monomer composition according to  claim 7 , wherein:
 the step of adding water comprises:   repeatedly adding water of 4 times the weight of the polycarbonate-based resin to the depolymerization reaction product 3 to 5 times.   
     
     
         12 . The method for preparing a monomer composition according to  claim 7 , further comprising:
 a step of purifying the extracted aromatic diol compound.   
     
     
         13 . The method for preparing a monomer composition for synthesizing recycled plastic according to  claim 12  wherein:
 the step of purifying the extracted aromatic diol compound comprises a step of washing the extracted aromatic diol compound. 
 
     
     
         14 . The method for preparing a monomer composition according to  claim 13 , wherein:
 the washing step comprises:   a step of washing the extracted aromatic diol compound with a first solvent at a temperature of 10° C. or more and 30° C. or less; and   a step of washing the extracted aromatic diol compound with a second solvent at a temperature of 40° C. or more and 80° C. or less.   
     
     
         15 . The method for preparing a monomer composition according to  claim 14 , wherein
 the first solvent is an organic solvent.   
     
     
         16 . The method for preparing a monomer composition according to  claim 14 , wherein
 the second solvent is water.   
     
     
         17 . The method for preparing a monomer composition according to  claim 14 , wherein
 a difference value between the temperature of the step of washing with the seconds solvent at a temperature of 40° C. or more and 80° C. or less, and the temperature of the step of washing with ftthe first solvent at a temperature of 10° C. or more and 30° C. or less is 20° C. or more and 50° C. or less.   
     
     
         18 . The method for preparing a monomer composition according to  claim 7 , further comprising:
 a step of adding an adsorbent to the depolymerization reaction product to perform an adsorption purification and then removing the adsorbent, before the step of adding water of 12 times or more the weight of the polycarbonate-based resin to the depolymerization reaction product to extract the aromatic diol compound.   
     
     
         19 . A recycled plastic, comprising:
 a reaction product of the monomer composition of  claim 1  and a comonomer.   
     
     
         20 . A molded product, comprising:
 the recycled plastic of  claim 19 .