US 4,728,045 A · Method for reclaiming bonded, two-resin articles

Abstract

A method and apparatus for reclaiming reusable resin materials from bottles and other scrap articles each comprising a first low density resin component (e.g., polyethylene) bonded to a second high density resin component (e.g., polyethylene terephthalate); the scrap articles are granulated to form a primary particulate scrap that is air classified to remove paper and film from labels, then flotation separated into a lightweight first resin (PE) material that is dried and air classified for re-use, and a secondary particulate scrap. The secondary scrap is vigorously washed in a hot aqueous medium to disrupt bonds in chips containing both resins, then thoroughly rinsed and again flotation separated into a heavy second resin material that is dried and air cleaned for re-use; there is also a residual low density scrap from the second flotation stage that is returned to the first flotation stage. The flotation separation stages each include a first auger in an apertured-bottom trough positioned near the top of a flotation tank with inlet means depositing particulate scrap and flotation liquid scrap in one end of the trough; the heavy material output is afforded by a second auger in the bottom of the tank, whereas the lightweight material outlet is an overflow weir at one side of the tank.

Claims26

Dependent claims

A process for reclaiming reusable resin materials from scrap articles each comprising at least one component formed of a first resin having a first, low density, bonded to at least one component formed of a second resin having a second, higher density, comprising the following steps:

A. comminuting the scrap articles to form a primary particulate scrap;
B. separating particles of the two resins by flotation of the primary particulate scrap in a liquid having a density intermediate the first and second resin densities, producing a reusable first resin material and a secondary particulate scrap;
C. vigorously washing the secondary particulate scrap to break down the bonds in particles containing both of the first and second resins;
D. and again separating particles of the two resins, by flotation of the washed secondary particulate scrap from step C in the same manner as in Step B, producing a reusable second resin material and a residual low density scrap.

1 more element

A. comminuting the scrap articles to form a primary particulate scrap;
A1. air classifying the primary particulate scrap after comminution to remove paper, film and fines therefrom;
B. separating particles of the two resins by flotation of the primary particulate scrap in a liquid having a density intermediate the first and second resin densities, producing a reusable first resin material and a secondary particulate scrap;
B1. rinsing and drying the reusable first resin material after separation in step B;
B2. air classifying the rinsed and dried reusable first resin material from step B1 to remove fines;
C. vigorously washing the secondary particulate scrap from step B to break down the bonds in particles containing both of the first and second resins;
D. again separating particles of the two resins, by flotation of the washed secondary particulate scrap from step C in the same manner as in step B, producing a reusable second resin material and a residual low density scrap;
D1. rinsing and drying the reusable second resin material after separation in step D;
D2. air classifying the rinsed and dried reusable second resin material from step D1 to remove fines;
and
D3. electrostatically separating conductive metal particles from the reusable second resin material subsequent to one of steps D1 and D2.

8 more elements

Dependencies are inferred from the claim text.

Method for reclaiming bonded, two-resin articles

Life of this patent

Method for reclaiming bonded, two-resin articles

Life of this patent

Abstract

Claims26