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.

Claims

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.sub.1/W.sub.0   [Equation 1] wherein in Equation 1, W.sub.0 is a mass of the aromatic diol compound obtained during 100% decomposition, and W.sub.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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0129] FIG. 1 shows a schematic diagram of the extraction process of Example.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0130] Hereinafter, the present disclosure will be explained in detail with reference to the following examples. However, these examples are for illustrative purposes only, and the scope of the present disclosure is not limited thereto.

EXAMPLE: PREPARATION OF RECYCLED BISPHENOL A MONOMER COMPOSITION

Example 1

[0131] (1. Decomposition step) 1 mol of Pretreated waste polycarbonate (PC) was dissolved in 17 mol of methylene chloride (MC), and then added together with 11 mol of ethanol (EtOH) and 0.25 mol of sodium hydroxide (NaOH) to a 3 L high-pressure reactor, and the mixture was stirred at 60° C. for 6 hours to proceed a PC depolymerization reaction.

[0132] (2. Neutralization stage) The depolymerization reaction product was cooled to 30° C. or less, and then the product containing bisphenol A was neutralized using 0.25 mol of 10% hydrochloric acid (HCl) at 20˜30° C.

[0133] (3-1. Purification-Adsorption step) After that, in the product whose pH has been lowered to less than 2, charcoal as an adsorbent was added at a ratio of 50 wt % relative to waste polycarbonate, purified through adsorption for 3 hours, and then filtrated using Celite to remove the absorbent.

[0134] (3-2. Purification-Extraction step) After that, the extraction process of adding water of twice the weight of waste polycarbonate, stirring the mixture and then then removing the aqueous layer was repeated 5 times. Water of twice the weight of waste polycarbonate was added once more, and immediately, crystallized bisphenol A (BPA) was formed between the aqueous layer and the MC layer, and bisphenol A (BPA) was recovered through vacuum filtration.

[0135] (3-3. Purification-Washing step) After that, the residue from which diethyl carbonate (DEC) was removed was primarily washed using methylene chloride (MC) (1 time the mass of PC used) at 20 to 30° C., and vacuum filtered. The filtrate was secondarily washed using water (three times the mass of PC used) at a temperature of 50° C.

[0136] (4. Drying step) After that, it was dried in a vacuum oven at 40° C. to prepare a recycled bisphenol A monomer composition in which recycled bisphenol A (BPA) was recovered.

Example 2

[0137] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in the (3-2. Purification-Extraction step) of Example 1, the extraction process of adding water of twice the weight of waste polycarbonate, stirring the mixture and then then removing the aqueous layer was repeated 6 times, and water of twice the weight of waste polycarbonate was added once more.

Example 3

[0138] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in the (3-2. Purification-Extraction step) of Example 1, the extraction process of adding water of twice the weight of waste polycarbonate, stirring the mixture and then then removing the aqueous layer was repeated 7 times, and water of twice the weight of waste polycarbonate was added once more.

Example 4

[0139] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in the (3-2. Purification-Extraction step) of Example 1, the extraction process of adding water of 4 times the weight of waste polycarbonate, stirring the mixture and then then removing the aqueous layer was repeated 2 times, and water of 4 times the weight of waste polycarbonate was added once more.

Example 5

[0140] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in the (3-2. Purification-Extraction step) of Example 1, water of 12 times the weight of waste polycarbonate was added and stirred, then crystallized bisphenol A (BPA) was formed between the aqueous layer and the MC layer, and bisphenol A (BPA) was recovered through vacuum filtration.

COMPARATIVE EXAMPLE: PREPARATION OF RECYCLED BISPHENOL A MONOMER COMPOSITION

Comparative Example 1

[0141] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in the (3-2. Purification-Extraction step) of Example 1, the extraction process of adding water of twice the weight of waste polycarbonate, stirring the mixture and then then removing the aqueous layer was repeated 4 times, water of twice the weight of waste polycarbonate was added once more, and the mixture was allowed to stand for 4 to 5 hours.

Comparative Example 2

[0142] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in the (3-2. Purification-Extraction step) of Example 4, the extraction process of adding water of 4 times the weight of waste polycarbonate, stirring the mixture and then then removing the aqueous layer was performed once, water of 4 times the weight of waste polycarbonate was added once more, and the mixture was allowed to stand for 4 to 5 hours.

Experimental Example

[0143] The physical properties of the recycled bisphenol A monomer compositions obtained in the Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

1. Purity

[0144] 1 wt % of the recycled bisphenol A monomer composition was dissolved in acetonitrile (ACN) solvent under normal pressure and 20 to 30° C. conditions, and then the purity of bisphenol A (BPA) was analyzed by ultraperformance liquid chromatography (UPLC) on a Waters HPLC system using ACQUITY UPLC®BEH C18 1.7 μm (2.1*50 mm column).

2. Color Coordinates (L*, a*, and b*)

[0145] The color coordinates of the recycled bisphenol A monomer compositions were analyzed in reflection mode using HunterLab UltraScan PRO Spectrophotometer.

3. Yield

[0146] The weight of BPA produced during 100% decomposition of the polycarbonate used in the reaction was measured, the weight of the obtained BPA was measured, and the yield of BPA was calculated according to the following Equation 1.

Yield (%)=W.sub.1/W.sub.0   [Equation 1] [0147] in Equation 1, W.sub.0 is the mass of the aromatic diol compound obtained during 100% decomposition, and W.sub.1 is the mass of the aromatic diol compound actually obtained. Specifically, when about 100 g of polycarbonate was decomposed, the theoretical mass of BPA obtained at 100% decomposition is 89 g. If the mass of the actually obtained BPA is 80 g, the yield is 80/89*100=90%.

TABLE-US-00001 TABLE 1 Measurement result of Experimental Example 1 Recycled bisphenol A monomer composition Purity Yield Category Extraction condition (%) L* a* b* (%) Example 1 Water(2 times the weight of PC)/6 99.3 96.10 0.30 2.34 69 times Example 2 Water(2 times the weight of PC)/7 99.2 96.07 0.32 2.36 64 times Example 3 Water(2 times the weight of PC)/8 99.3 96.11 0.29 2.33 60 times Example 4 Water(4 times the weight of PC)/3 98.6 95.40 0.48 2.79 62 times Example 5 Water(12 times the weight of PC)/1 98.0 95.22 0.54 3.07 59 time Comparative Water(2 times the weight of PC)/5 98.9 95.64 0.38 2.66 50 Example 1 times Comparative Water(4 times the weight of PC)/2 96.8 94.89 0.61 3.59 42 Example 2 times

[0148] As shown in Table 1, the recycled bisphenol A monomer compositions obtained in Examples 1 to 5 exhibited high purity of 98% to 99.3%. Also, the recycled bisphenol A monomer compositions obtained in Examples 1 to 5 exhibited a color coordinates L* of 95.22 to 96.11, a* of 0.29 to 0.54, and b* of 2.33 to 3.07, showing excellent optical properties. In addition, the recycled bisphenol A monomer compositions obtained in Examples 1 to 5 were measured to have a BPA yield of 59% to 69%. On the other hand, the recycled bisphenol A monomer composition obtained in Comparative Examples 1 and 2 had a BPA yield of 42% to 50%, which was decreased compared to that of Examples.