Twin-Screw Resin Decomposition With Backflow Suppression

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Solution Overview

Problem

Existing decomposition methods under subcritical or supercritical conditions face high initial costs due to the need for dedicated apparatus and are prone to backflow, which disrupts the continuous processing of resin decomposition.

Innovation Solution

A decomposition method and apparatus using a twin-screw extruder with integrated sensors and a backflow suppression mechanism, including a relief valve controlled by temperature and pressure measurements, to maintain stable conditions and prevent backflow during resin decomposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealed apparatus is used for decomposition under subcritical or supercritical conditions, then the decomposition can be performed safely, but the initial cost increases significantly due to the need for dedicated apparatus

Engineering Contradiction:

Improvesafe decompositionVSAvoidinitial cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies universality by using a standard extruder that can serve dual purposes: conventional resin processing and decomposition under subcritical/supercritical conditions. The extruder is equipped with a backflow suppression mechanism and measurement sensors, allowing it to safely handle high-pressure fluid injection while maintaining its原有 extrusion function, thereby avoiding the need for completely dedicated sealed apparatus

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces a backflow suppression mechanism as an intermediary component between the resin supply and decomposition zones. This mechanism, combined with measurement sensors that monitor temperature and pressure, acts as a mediator to prevent harmful backflow while enabling the use of standard equipment, thus resolving the contradiction between safety and cost

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If high temperature and high pressure conditions are applied for resin decomposition, then the decomposition efficiency is improved, but backflow of melt-plasticized resin occurs disrupting continuous processing

Engineering Contradiction:

Improvedecomposition efficiencyVSAvoidcontinuous processing

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements feedback control by installing measurement sensors that continuously monitor temperature and pressure conditions within the extruder. When backflow is detected through changes in these parameters, the system automatically adjusts the backflow suppression mechanism to restore proper flow conditions, ensuring continuous processing while maintaining high decomposition efficiency

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The backflow suppression mechanism operates preliminarily to prevent backflow before it disrupts continuous processing. By proactively suppressing backflow tendencies through controlled pressure differential and flow resistance, the system maintains stable decomposition conditions without interruption

Inventive Principle:

Principle #9Preliminary anti-action

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

Enables safe and continuous resin decomposition without backflow, reducing costs by utilizing existing equipment and ensuring efficient processing under subcritical or supercritical conditions.

Implementation Method 1

decomposing the melt-plasticized thermoplastic resin by exposing the melt-plasticized thermoplastic resin to a subcritical state or a supercritical state

Methodology Applied

Scientific EffectSubcritical state:

Implementation Method 2

decomposing the melt-plasticized thermoplastic resin by exposing the melt-plasticized thermoplastic resin to a subcritical state or a supercritical state

Methodology Applied

Scientific EffectSupercritical state: Supercritical Fluid

Implementation Method 3

at least one selected from a resin thermometer for measuring a temperature of the thermoplastic resin

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

a resin pressure gauge for measuring a pressure of the thermoplastic resin

Methodology Applied

Scientific EffectPressure measurement:

Data Source

PatentUS20260035532A1Decomposition method and decomposition apparatus for resin

Publication Date: 2026.02.05 THE JAPAN STEEL WORKS LTD

AI summary

A decomposition method and a decomposition apparatus for resin capable of safely and efficiently decomposing a resin are provided. A decomposition apparatus for resin 10 includes: a cylinder 12; a resin supplier 11 supplying a thermoplastic resin to the cylinder 12; a screw 12a transporting the supplied thermoplastic resin and a melt-plasticized thermoplastic resin; a fluid supplier 13 supplying a heated and pressurized fluid into the cylinder in order to decompose the melt-plasticized thermoplastic resin in a subcritical state or a supercritical state; an extruder 14 provided at a tip of the cylinder 12 and discharging a decomposed product of the thermoplastic resin to outside of the cylinder; a rotary drive mechanism 15 rotationally driving the screw 12a; and a backflow suppression mechanism 16 suppressing backflow of the melt-plasticized thermoplastic resin in the cylinder 12.