Method and system for recovering polyethylene from waste resin-compounds

• US 6,225,360 B1
• Filed: 06/21/1999
• Issued: 05/01/2001
• Est. Priority Date: 06/20/1998
• Status: Expired due to Fees

• Current Assignee: Kwang Kim
• Original Assignee: Kwang Kim
• Inventors: Kim, Sung-moon
• Primary Examiner(s): Cain, Edward J.
• Assistant Examiner(s): WYROZEBSKI LEE, KATARZYNA I
• Application Number:
  US09/334,573
• Time in Patent Office: 680 Days
• Field of Search: 134/38, 521/40, 521/40.5, 521/46.5, 521/47, 521/48, 528/493, 528/497, 528/503, 528/502 A
• US Class Current: 521/47
• CPC Class Codes: C08J 11/08 using selective solvents for polymer components
• CPC Class Codes: C08J 2323/06 Polyethene
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling

Abstract

Method and system for recovering polyethylene from a polyethylene-containing scrap material. The recovery method includes the steps of putting the scrap material containing polyethylene into a solvent mixture containing a polyethylene-soluble solvent and a polyethylene-insoluble solvent in a ratio of 1:1˜1:3 based on volume, heating the mixture at a temperature of 60˜145° C. to dissolve the polyethylene from the scrap material, resulting in a mixture of a polyethylene solution and insoluble substances. Then, the resulting mixture is filtered to separate the polyethylene solution and the insoluble substances, and polyethylene is deposited by cooling the separated polyethylene solution. Then, a mixture of the polyethylene deposition and the solvent mixture is filtered to separate the polyethylene deposition. Therefore, a huge amount of polyethylene-containing scrap material can be continuously processed, without generation of harmful materials, and can simply recover a high-quality PE at low cost.

Claims

1. A method for recovering polyethylene from scrap material containing polyethylene, consisting of the steps of:

(a) putting the scrap material containing polyethylene into a solvent mixture containing a polyethylene-soluble solvent and a polyethylene-insoluble solvent in a ratio of 1;

1˜

1;

3 based on volume, heating the mixture at a temperature of 60˜

145 degrees C. to dissolve the polyethylene from the scrap material, resulting in a mixture of a polyethylene solution and insoluble substances;

(b) filtering the resulting mixture of step (a) to separate the polyethylene solution and the insoluble substances,

drying the separated insoluble substances to evaporate the solvent mixture remaining in the insoluble substance,

condensing the evaporated solvent mixture, and recirculating the condensed solvent mixture to be used for the dissolution step (a);

(c) depositing polyethylene by cooling the separated polyethylene solution to 50 degrees C. or less; and

(d) filtering a mixture of the polyethylene deposition and the solvent mixture, to separate the polyethylene deposition,

recirculating the filtered solvent mixture for use in the dissolution step (a) and drying the separated polyethylene deposition to evaporate the remaining solvent mixture,

condensing the evaporated solvent mixture, and

recirculating the condensed solvent mixture for use in the dissolution step (a).

2. The method of claim 1, wherein the polyethylene-soluble solvent comprises at least one hydrocarbon solvent selected from the group consisting of benzene, toluene, xylene and solvent naphtha.

3. The method of claim 1, wherein the polyethylene-insoluble solvent comprises at least one solvent selected from the group consisting of ethylacetate, methylisobutylketone, methylethylketone, dioxane, 2-ethylbutylacetate, methyl n-amylketone.

4. The method of claim 1, wherein the polyethylene-containing scrap material comprises at least one resin selected from the group consisting of polyvinylchloride, nylon and polyester.

5. The method of claim 4, wherein the polyethylene-containing scrap material is a mat for vehicles formed by sticking polyester fiber to a polyethylene base.