Method and plant for the manufacture of polymer particles

• US 20080249199A1
• Filed: 11/06/2007
• Published: 10/09/2008
• Est. Priority Date: 11/23/2006
• Status: Active Grant

• Current Assignee: Sulzer Management AG (Sulzer AG)
• Original Assignee: Sulzer Chemtech AG (Sulzer AG)
• Inventors: Nising, Philip
• Granted Patent: US 7,625,953 B2
• Time in Patent Office: Days
• US Class Current: 521/40
• CPC Class Codes: B29C 44/3442 Mixing, kneading or conveying the foamable material mixing plastics B29B7/00; mixing in general B01F
• CPC Class Codes: B29C 44/3461 Making or treating expandable particles
• CPC Class Codes: C08J 11/04 of polymers
• CPC Class Codes: C08J 2300/30 Polymeric waste or recycled polymer
• CPC Class Codes: C08J 3/12 Powdering or granulating
• CPC Class Codes: C08J 9/16 Making expandable particles
• CPC Class Codes: Y02P 20/143 the feedstock being recycled material, e.g. plastics
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling
• CPC Class Codes: Y10S 264/05 Use of one or more blowing agents together

Abstract

The method for the manufacture of foamed or foamable polymer particles employs a mixture of a polymer melt and a recycled polymer melt produced from recycled, propellant-containing polymer particles. The associated plant for the manufacture of the foamed or foamable polymer particles is provided with an apparatus for the processing of recycled, propellant-containing polymer particles.

Claims

1. A method for the manufacture of foamed or foamable polymer particles comprising the steps of

melting a mass of recycled propellant-containing polymer particles;

removing propellant from the melted mass;

adding a metered amount of additive to the melted mass to form an additive-containing recycled polymer melt;

forming a polymer melt;

adding a metered amount of propellant to said polymer melt to form a propellant-containing polymer melt;

mixing the additive-containing recycled polymer melt and the propellant-containing polymer melt to obtain a homogeneous polymer melt with a homogeneous distribution of propellant and additive;

thereafter cooling the homogeneous polymer melt; and

granulating the cooled homogeneous polymer melt into a plurality of polymer particles.

2. A method as set forth in claim 1 wherein the additive is added to the melted mass of recycled propellant-containing polymer particles after removal of propellant therefrom in one of a liquid form, a solid form and a master batch form.

3. A method as set forth in claim 1 wherein said step of granulating the cooled homogeneous polymer melt occurs under water.

4. A method as set forth in claim 3 wherein said step of granulating the cooled homogeneous polymer melt produces predominantly spherical or ellipsoid particles.

5. A method as set forth in claim 4 wherein the spherical or ellipsoid particles comprise a cutting edge.

6. A method as set forth in claim 4 further comprising the step of thermally treating the produced particles for improving the roundness of the particles.

7. A method as set forth in claim 1 wherein the proportion of recycled polymer melt in the homogeneous polymer melt is between 0.5% and 100%.

8. A method as set forth in claim 1 wherein the additive includes at least one of a flame protection agent, a lubricant, a nucleating agent, a softener, a UV protection agent, an insecticide, a pigment, graphite and/or carbon black particles, metal particles, a master batch and a mixture thereof.

13. A polymer particle made in accordance with the method of claim 1 characterized in having a cutting edge.

9. A plant for the manufacture of foamed or foamable polymer particles comprising

a side extruder for processing recycled propellant-containing polymer particles;

a heating means for the production of a recycling polymer melt from the recycled propellant-containing polymer particles in said extruder;

a degasification apparatus for the degasification of the recycling polymer melt in said extruder;

a first mixing apparatus for mixing of the recycling polymer melt to produce an essentially homogenous recycled polymer melt;

at least one of a polymerisation plant having a reactor and a degasification apparatus for the manufacture of a polymer melt and a melting apparatus for the manufacture of a polymer melt by melting of polymer granulate;

a supply apparatus for metering a propellant into the polymer melt;

a second mixing apparatus for mixing the polymer melt and propellant;

a cooling apparatus for cooling the propellant-containing polymer melt; and

a third mixing apparatus for mixing the homogeneous recycled polymer melt and propellant-containing polymer melt to obtain a homogeneous polymer melt with a homogeneous distribution of propellant.

10. A plant as set forth in claim 9 further comprising a metering apparatus downstream of said degasification apparatus for metering an additive into the recycled polymer melt.

11. A plant as set forth in claim 10 wherein at least one of said mixing apparatus is a static mixer.

12. A plant as set forth in claim 10 wherein said cooling apparatus contains a static mixer/heat exchanger.