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. Also, the present disclosure relates to a monomer composition for synthesizing recycled plastic that contains a by-product with a high added value 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 the monomer composition has a color coordinate L* of more than 95, and a color coordinate a* of −0.06 to 0.10, and wherein the monomer composition is a recovered product from a polycarbonate-based resin.

2. The monomer composition according to claim 1, wherein the monomer composition for synthesizing recycled plastic has a color coordinate b* of less than 2.

3. The monomer composition according to claim 1, wherein the aromatic diol compound has a purity of more than 99%.

4. The monomer composition according to claim 1, further comprising two or more compounds selected from the group consisting of dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, wherein the dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate are recovered products from the polycarbonate-based resin.

5. A monomer composition for synthesizing recycled plastic, comprising: two or more compounds selected from the group consisting of dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate, wherein the dimethyl carbonate, diethyl carbonate and ethylmethyl carbonate are recovered products from a polycarbonate-based resin.

6. The monomer composition according to claim 5 wherein the monomer composition comprises the dimethyl carbonate at a ratio of 1% to 30%, the diethyl carbonate at a ratio of 10% to 65%, and the ethylmethyl carbonate at a ratio of 30% to 60%.

7. A method for preparing a monomer composition for synthesizing recycled plastic, the method comprising the steps of: depolymerizing a polycarbonate-based resin in the presence of a solvent containing methanol and ethanol; and separating a carbonate precursor from the depolymerization reaction product.

8. The method for preparing a monomer composition according to claim 7, wherein ethanol is contained in an amount of 1 mole to 15 moles relative to 1 mole of methanol.

9. The method for preparing a monomer composition according to claim 7, wherein a content of the methanol and ethanol is 10 moles to 15 moles relative to 1 mole of the polycarbonate-based resin.

10. The method for preparing a monomer composition according to claim 7, wherein the depolymerization reaction of the polycarbonate-based resin is carried out by reacting a base in an amount of 0.5 moles or less relative to 1 mole of the polycarbonate-based resin.

11. The method for preparing a monomer composition according to claim 7, wherein the solvent further comprises at least one organic solvent selected from the group consisting of tetrahydrofuran, toluene, methylene chloride, chloroform, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate and dipropyl carbonate.

12. The method for preparing a monomer composition according to claim 11, wherein a content of the organic solvent is 16 to 20 moles relative to 1 mole of the polycarbonate-based resin.

13. The method for preparing a monomer composition according to claim 11, wherein a content of the organic solvent is 1.5 moles to 2 moles relative to 1 mole of a total of methanol and ethanol.

14. The method for preparing a monomer composition according to claim 7, wherein the step of depolymerizing a polycarbonate-based resin in the presence of a solvent containing methanol and ethanol comprises: adding a base to a mixed solvent of methanol and ethanol and an organic solvent to prepare a catalyst solution; and adding the polycarbonate-based resin to the catalyst solution and stirring a mixture.

15. The method for preparing a monomer composition according to claim 7, wherein the step of separating a carbonate precursor from the depolymerization reaction product comprises: a reduced pressure distillation step of the depolymerization reaction product.

16. The method for preparing a monomer composition according to claim 7, further comprising: a purification of the depolymerization reaction product from which the carbonate precursor has been separated.

17. The method for preparing a monomer composition according to claim 7, further comprising a neutralization reaction step of the depolymerization reaction product with an acid, before the separating step.

18. A recycled plastic, comprising: a reaction product of the monomer composition of claim 1 and a comonomer.

19. A recycled plastic, comprising: a reaction product of the monomer composition of claim 5 and a comonomer.

20. A molded product comprising the recycled plastic of claim 18.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0144] 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

[0145] (1. Decomposition step) 28 mol of Mixed solvent of ethanol/methanol/methylene chloride (molar ratio of ethanol: methanol: methylene chloride=10:1:17) and 0.25 mol of sodium hydroxide were added to a 250 ml 3-neck flask, and stirred. Then, 1 mol of waste polycarbonate (PC) was added thereto, and stirred at 60° C. for 6 hours to proceed a PC depolymerization. The depolymerization reaction product was cooled to room temperature to obtain a bisphenol A mixture.

[0146] (2. Neutralization stage) The mixture containing the bisphenol A was neutralized using 0.25 mole of 1N hydrochloric acid (HC1) at 20-30° C., the aqueous layer and the organic layer were separated, and the organic layer was filtered through vacuum filtration to obtain a liquid containing bisphenol A.

[0147] (3-1. Purification-Distillation step) After that, 23 mol of water was added to the organic layer lowered to less than pH 6, and then the by-product diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC), and the previously used methylene chloride, methanol, ethanol, and water were recovered through a low-temperature distillation reducing pressure from 250 mbar and 20-30° C. to 30 mbar and

[0148] (3-2. Purification-Washing step) When distillation was carried out for a certain period of time through the above process, bisphenol-A was precipitated and formed into a slurry state. The solid was vacuum filtrated, recovered, and then primarily washed using 3 moles of methylene chloride (MC) at 20-30° C., vacuum-filtered, recovered, and secondarily washed using 23 mol of water at 50° C.

[0149] (4-1. Additional purification step-redissolving step) 16.6 mol of ethanol was added to the washed material and redissolved.

[0150] (4-2. Additional purification step-Adsorption step) After that, lignite activated carbon was added at a ratio of 50 wt. % relative to waste polycarbonate, and purified through adsorption for 3 hours, and then filtered to remove the lignite activated carbon.

[0151] (4-3. Additional purification step-Recrystallization step) After that, 260 mol of water was slowly added to recrystallize bisphenol A, and then the obtained slurry was vacuum filtrated at 20 to 30° C. to recover bisphenol A (BPA) crystals.

[0152] (5. Drying step) After that, it was dried in a vacuum convection oven at 40° C. to prepare a recycled bisphenol A monomer composition in which recycled bisphenol A (BPA) was recovered.

Example 2

[0153] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in Example 1, the molar ratio of ethanol: methanol:methylene chloride was changed to 9:2:17 as shown in Table 1 below.

Example 3

[0154] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in Example 1, the molar ratio of ethanol:methanol:methylene chloride was changed to 8:3:17 as shown in Table 1 below.

Example 4

[0155] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in Example 1, the molar ratio of ethanol:methanol:methylene chloride was changed to 7:4:17 as shown in Table 1 below.

Example 5

[0156] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in Example 1, the molar ratio of ethanol:methanol:methylene chloride was changed to 6:5:17 as shown in Table 1 below.

COMPARATIVE EXAMPLE

Preparation of recycled bisphenol A monomer composition

Comparative Example 1

[0157] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in Example 1, the molar ratio of ethanol:methanol:methylene chloride was changed to 0:11:17 as shown in Table 1 below.

Comparative Example 2

[0158] A recycled bisphenol A monomer composition was prepared in the same manner as in Example 1, except that in Example 1, the molar ratio of ethanol:methanol:methylene chloride was changed to 11:0:17 as shown in Table 1 below.

Experimental Example

[0159] The physical properties of the recycled bisphenol A monomer compositions or by-products obtained in the Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

[0160] 1. Purity

[0161] 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).

[0162] 2. Color coordinates (L*, a*, and b*)

[0163] The color coordinates of the recycled bisphenol A monomer compositions were analyzed in reflection mode using HunterLab UltraScan PRO Spectrophotometer.

[0164] 3. Content of impurities (DMC, DEC, EMC)

[0165] 1 ml of a by-product mixture solution of diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) containing MC, MeOH, EtOH, and water separated in the distillation step was taken as a sample, and gas chromatography (GC) analysis was performed under the following conditions.

[0166] <Gas Chromatography (GC) conditions>

[0167] {circle around (1)} Column: HP-1(L:30m, ID:0.32 mm, film:1.05m)

[0168] {circle around (2)} Injection volume: 1

[0169] {circle around (3)} Inlet Temp.: 260° C., Pressure: 6.92 psi, Total flow: 64.2 ml/min, Split flow: 60 ml/min, spilt ratio: 50:1

[0170] {circle around (4)} Column flow: 1.2ml/min

[0171] {circle around (5)} Oven temp.: 70° C./3 min-10° C./min-280° C./41 min (Total 65 min)

[0172] {circle around (6)} Detector Temp.:280° C., H.sub.2: 35 ml/min, Air: 300 ml/min, He: 20 ml/min

[0173] {circle around (7)} GC Model: Agilent 7890

[0174] Then, each standard sample of diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) was dissolved in EtOH solvent at the same concentration, the peak area measured through GC was set as a reference value, and the ratio of the peak area values of each carbonate by-product (diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC)) in the sample (the peak area value of the sample / the peak area value of the standard sample) was obtained.

[0175] When the sum of the ratio of the peak area values of each of the carbonate by-products (diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC)) obtained through the GC result was set to 100%, the relative proportions of each carbonate by-product were calculated and shown in Table 1 below.

TABLE-US-00001 TABLE 1 Measurement result of Experimental Example 1 Recycled bisphenol A monomer composition Molar ratio of Purity Mixing ratio of impurities Category ethanol:methanol (%) L* a* b* DMC(%) EMC(%) DEC(%) Example 1 10:1  99.1 96.3 0.09 1.80 3 37 60 Example 2 9:2 99.1 96.1 0.05 1.72 8 51 37 Example 3 8:3 99.2 96.0 0.03 1.6 14 56 23 Example 4 7:4 99.4 96.0 −0.01 1.49 19 57 21 Example 5 6:5 99.4 95.9 −0.04 1.49 25 55 16 Comparative  0:11 99.4 95.77 −0.08 1.51 100 0 0 Example 1 Comparative 11:0  99.0 96.3 0.11 1.80 0 0 100 Example 2

[0176] As shown in Table 1, the recycled bisphenol A monomer compositions obtained in Examples 1 to 5 exhibited high purity of 99.1% to 99.4%. Also, the recycled bisphenol A monomer compositions obtained in Examples 1 to 5 exhibited a color coordinates L* of 95.9 to 96.3, a* of −0.04 to 0.09, and b* of 1.49 to 1.80, showing excellent optical properties. In addition, in the recycled bisphenol A monomer compositions obtained in Examples 1 to 5, all three carbonates of diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) were obtained as by-products. On the other hand, the recycled bisphenol A monomer composition obtained in Comparative Example 2 had a purity of 99.0%, which was decreased compared to that of Examples. Further, the recycled bisphenol A monomer composition obtained in Comparative Example 1 exhibited a color coordinate L* of 95.77, a* of −0.08, and b* of 1.51, and the recycled bisphenol A monomer composition obtained in Comparative Example 2 exhibited a color coordinate a* of 0.11, showing poor optical properties as compared to those of Examples. Further, in the recycled bisphenol A monomer composition obtained in Comparative Example 1, only dimethyl carbonate (DMC) was obtained as a by-product, and in the recycled bisphenol A monomer composition obtained in Comparative Example 2, only diethyl carbonate (DEC) was obtained as a by-product.