Polystyrene Recycling Solvent Selection

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Solution Overview

Problem

Current recycling methods for polystyrene waste face challenges due to the use of d-limonene as a solvent, which has a strong citrus odor, high boiling point, instability, and availability issues, making it unsuitable for industrial-scale recycling.

Innovation Solution

The method employs 1,3-dioxolane or isoamyl acetate as solvents for dissolving polystyrene in a closed circulation system, allowing for efficient recycling at lower temperatures and pressures, reducing environmental impact and operational costs, and maintaining the quality of recycled polystyrene.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If d-limonene is used as a solvent for polystyrene dissolution, then the polystyrene can be dissolved and recycled, but the solvent has strong citrus odor, high boiling point, and instability issues

Engineering Contradiction:

Improvesolvent stabilityVSAvoidcitrus odor and high boiling point

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the solvent system by replacing d-limonene with 1,3-dioxolane or isoamyl acetate. These alternative solvents have different physical and chemical properties including lower boiling points (1,3-dioxolane: 75°C, isoamyl acetate: 142°C versus d-limonene: 176°C), no strong citrus odor, and higher stability, thereby resolving the technical contradiction between solvent effectiveness and harmful characteristics

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs solvents that are more readily available and less dependent on natural crop variations compared to d-limonene. The selected solvents (1,3-dioxolane and isoamyl acetate) can be produced synthetically with consistent quality and availability, eliminating the instability and availability issues associated with natural citrus extraction

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Productivity

If high temperature evaporation is used to recover solvent from dissolved polystyrene, then the solvent can be separated efficiently, but energy consumption increases and polystyrene may degrade

Engineering Contradiction:

Improvesolvent separation efficiencyVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent changes the temperature parameter for solvent evaporation from conventional high temperatures to a controlled range of 20-70°C. This parameter change is made possible by selecting solvents with appropriate boiling points (1,3-dioxolane: 75°C, isoamyl acetate: 142°C) that allow efficient separation at lower temperatures, thereby reducing energy consumption while preventing polystyrene degradation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the phase transition (evaporation) of the selected solvents at controlled temperatures. By choosing solvents with specific vapor pressures and boiling points, the process achieves efficient solvent-recovered polystyrene separation through phase transition at energy-efficient temperatures of 20-70°C

Inventive Principle:

Principle #36Phase transitions

3Ease of manufacture

If conventional disposal methods (landfill or incineration) are used for polystyrene waste, then waste management is simple, but environmental damage occurs

Engineering Contradiction:

Improvewaste management simplicityVSAvoidenvironmental pollution

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent implements a dissolution recycling process that recovers polystyrene from waste materials through solvent dissolution, filtration, and evaporation. This process transforms the waste management approach from simple disposal (landfill/incineration) to circular economy by recovering and reusing polystyrene, thereby eliminating environmental pollution while maintaining operational simplicity

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The patent converts polystyrene waste, which is typically harmful when disposed of in landfills or incinerated, into a valuable recyclable resource. By using selective solvents to dissolve and recover polystyrene from waste streams, the process transforms environmental liabilities into economic and environmental benefits, creating a sustainable recycling system

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 approach enables an energy-efficient, cost-effective, and environmentally friendly recycling process that produces polystyrene with properties similar to virgin polystyrene, minimizing solvent waste and degradation, and integrates well with existing industrial processes.

Implementation Method 1

dissolving the waste material to a solvent, which comprises 1,3-dioxolane or isoamyl acetate, in a dissolving unit thereby obtaining a solution comprising dissolved polystyrene

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 2

evaporating the solvent from the obtained solution comprising dissolved polystyrene at a temperature in the range of 20-70° C., at pressure of 50 mbar-1 atm

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS12162991B2Method for recycling polystyrene and solvent for dissolving polystyrene

Publication Date: 2024.12.10 FF FUTURE OY

AI summary

A method for recycling polystyrene in a dissolution recycling process, in which method 1,3-dioxolane or isoamyl acetate is used as a solvent for dissolving polystyrene.