Foamed Polymer Board from Mixed Plastic Waste

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Solution Overview

Problem

Existing processes for producing foamed polymer composite boards from mixed plastic waste result in boards that are not sufficiently rigid, lacking fibers, and suffer from irregular pore distribution and blowholes, making them unsuitable as replacements for MDF or plywood.

Innovation Solution

A production process involving melt-kneading of unsorted mixed plastic waste with a blowing agent in an extruder, followed by injection of the melt into a closed mold under pressure, where it foams and cools to form a homogeneous core layer. This process ensures uniform distribution of the blowing agent and avoids blowholes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If compression molding process is used with blowing agent introduced together with plastic granulate, then foamed board can be produced, but pore distribution becomes highly irregular and blowholes form

Engineering Contradiction:

Improvepore distribution uniformityVSAvoidboard quality (blowhole formation)

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The blowing agent is introduced in advance during the granulation process, creating pre-loaded granulates that contain the blowing agent uniformly distributed throughout the plastic material. This preliminary action ensures homogeneous distribution before molding, preventing irregular pores and blowholes in the final foamed board.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The process divides the blowing agent introduction into separate stages: first during granulation to create uniformly distributed pre-loaded granulates, then during injection molding. This segmentation allows precise control of blowing agent distribution, avoiding the problems of simultaneous introduction in compression molding.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If integral foam boards are produced from mixed plastics without fibers, then production simplicity is maintained, but board rigidity becomes insufficient for MDF/plywood replacement

Engineering Contradiction:

Improveproduction process simplicityVSAvoidboard rigidity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The invention creates a composite structure by injecting a plastic melt (which may contain fibers or filler materials) into a pre-formed foam core. This composite approach combines the lightweight properties of foam with the reinforcing effects of fibers or fillers, achieving both production simplicity and sufficient rigidity for MDF/plywood replacement.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The process utilizes porous foam materials as the core structure, which provides lightweight properties while maintaining structural integrity. The foam core is then combined with plastic melt injection to create a composite board that achieves the necessary rigidity without complex production processes.

Inventive Principle:

Principle #31Porous materials

3Quantity of substance

If blowing agent is introduced during compression molding, then foaming occurs, but the blowing agent cannot be distributed sufficiently homogeneously

Engineering Contradiction:

Improveblowing agent distribution uniformityVSAvoidpore size uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The blowing agent is introduced in advance during the granulation process, creating pre-loaded granulates with uniformly distributed blowing agent. This preliminary action ensures homogeneous distribution before molding, preventing irregular pores and blowholes in the final foamed board.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The process replaces the mechanical mixing method of compression molding with an injection molding system that uses fluid dynamics to distribute the plastic melt containing blowing agent. The injection process creates more uniform distribution through controlled flow and pressure, replacing the less effective mechanical mixing of compression molding.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The process achieves a highly homogeneous, blowhole-free core layer with a high degree of foaming, comparable in stiffness to MDF and plywood, and produces boards with fine and uniform pore distribution, suitable for various applications.

Implementation Method 1

plastic waste is processed in a melt-kneading step in an extruder to form a melt

Methodology Applied

Scientific EffectMelt-kneading:

Implementation Method 2

the melt foams and cools down to form a foamed core layer

Methodology Applied

Scientific EffectFoaming: Foam

Implementation Method 3

the melt foams and cools down to form a foamed core layer

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS20250043151A1Method for producing a foamed polymer composite board from mixed plastic waste

Publication Date: 2025.02.06 BOXS AG

AI summary

In a method for producing a polymer composite board from plastic waste, in which the plastic waste is processed in an extruder in a melt-kneading step to form a melt, the melt is introduced into an injector and injected under pressure into a cavity of a closed mold by the injector, in order to form a board. The melt is formed from a free-flowing agglomerate and a blowing agent. The free-flowing agglomerate is produced from unsorted, mixed plastic waste, and the melt is introduced into the closed mold via an injection nozzle along an end side of the cavity, in which mold the melt is foamed and cooled to form a foamed core layer of the polymer composite board.