Separating Cured Silicone From Plastic Using Density Stratification

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Solution Overview

Problem

The separation of cured silicone from plastic during recycling is challenging due to similar specific gravity, leading to lower quality recycled plastic and increased costs, as manual removal is necessary to avoid discoloration imperfections.

Innovation Solution

A method involving combining the cured silicone composition and plastic with a liquid of intermediate specific gravity, allowing stratification, and physically separating them by removing one stratum, utilizing an organopolysiloxane composition with specific gravity adjustments through void-creating materials like hollow glass spheres to facilitate floating or sinking based on desired separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If water washing is used to separate plastic from other materials, then materials of lower specific gravity float and can be separated, but materials with similar specific gravity cannot be adequately separated

Engineering Contradiction:
Improveseparation processVSAvoidseparation quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the specific gravity parameter of the separation liquid from water (1.0) to a liquid with specific gravity of 0.94-0.98, enabling adequate separation of cured silicone from plastic materials that have similar specific gravity values close to 1.0

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a specific gravity-adjusted liquid as an intermediary separation medium between the cured silicone and plastic materials, allowing stratification and separation based on density differences that are not achievable with water alone

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If manual removal of cured silicone is performed to maintain plastic quality, then discoloration imperfections are avoided, but recycling costs greatly increase

Engineering Contradiction:
Improveplastic qualityVSAvoidrecycling cost
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent enables the separation system to automatically separate cured silicone from plastic through density-based stratification in the specific gravity-adjusted liquid, eliminating the need for manual removal while maintaining plastic quality

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces the manual mechanical removal process with an automatic density-based separation system using a specific gravity-adjusted liquid, reducing labor costs while achieving consistent separation quality

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If cured silicone remains in plastic through recycling, then manual removal costs are avoided, but recycled plastic quality decreases due to discoloration

Engineering Contradiction:
Improverecycling costVSAvoidrecycled plastic quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent uses a specific gravity-adjusted liquid (0.94-0.98) as an intermediary medium that enables cured silicone to stratify and separate from plastic automatically, ensuring high-quality recycled plastic without manual intervention

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This method enables efficient separation of cured silicone from plastic without manual intervention, maintaining plastic quality and reducing recycling costs by ensuring effective stratification and subsequent separation.

Implementation Method 1

combining a composition comprising a cured silicone composition and a plastic with a liquid that has a specific gravity between that of the cured silicone composition and that of the plastic. The second step of the method comprises allowing the cured silicone composition and the plastic to stratify in the liquid

Methodology Applied
Scientific EffectSpecific gravity difference: Density Gradient

Implementation Method 2

utilizing an organopolysiloxane composition with specific gravity adjustments through void-creating materials like hollow glass spheres to facilitate floating or sinking based on desired separation

Methodology Applied
Scientific EffectVoid-creating materials: Porosity

Data Source

PatentEP2121818B1Method of recycling plastic
Publication Date: 2012.08.29 DOW SILICONES CORP

AI summary

The present invention relates to a method of separating a cured silicone composition and a plastic. The first step of the method comprises combining a cured silicone composition and a plastic with a liquid that has a specific gravity between that of the cured silicone composition and that of the plastic. The second step of the method comprises allowing the cured silicone composition and the plastic to stratify in the liquid, and the third step comprises physically separating the cured silicone composition and the plastic by removing one of the strata from the liquid.