Recycled PVC Sash Composition for Strength and Clean Disassembly

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Solution Overview

Problem

Existing recycled vinyl chloride-based resins used in sashes face issues such as reduced strength due to impurities, peeling interfaces, defective appearances, and difficulty in recycling due to crimped metal and resin frames, as well as the presence of lead-based stabilizers leading to thermal instability and foaming.

Innovation Solution

Incorporating additives like maleic anhydride, polytetrafluoroethylene, and silane coupling agents into the recycled vinyl chloride-based resin composition, using specific engaging structures for metal and resin frames, and controlling stabilizer ratios to improve strength, appearance, and recyclability, while managing waste materials through a management system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If a recycled vinyl chloride-based resin containing impurities is used, then resource recycling is achieved, but the strength and uniformity of the sash are reduced

Engineering Contradiction:
ImproverecyclabilityVSAvoidsash strength
Core Design Contradiction:
Ease of repairVSStrength

Solution Approach 1:

A master batch containing maleic anhydride is introduced as an intermediary substance during extrusion molding. This maleic anhydride acts as a chemical mediator that reacts with impurities in the recycled vinyl chloride-based resin, forming strong chemical bonds that bridge the resin matrix and impurity particles, thereby preventing interface peeling and improving overall sash strength while maintaining recyclability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention creates a composite material system where the recycled vinyl chloride-based resin is combined with maleic anhydride grafted components. This composite structure allows the resin to maintain its recyclability while the maleic anhydride modification enhances the material's internal bonding and interface adhesion, resolving the strength deficit caused by impurities

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If a recycled vinyl chloride-based resin is used, then environmental load reduction is achieved, but defective appearances occur due to impurities

Engineering Contradiction:
Improveenvironmental loadVSAvoidappearance quality
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The maleic anhydride in the master batch serves as a surface-modifying intermediary that chemically interacts with impurity surfaces. This modification creates a transition layer that improves the optical and surface properties of impurity-containing regions, making defects less conspicuous while maintaining the environmental benefit of using recycled material

Inventive Principle:
Principle #24Intermediary (Mediator)

3Stability of the object's composition

If lead-based stabilizers are used in recycled vinyl chloride-based resin, then thermal stability is improved, but foaming occurs during extrusion molding

Engineering Contradiction:
Improvethermal stabilityVSAvoidfoaming
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The invention changes the chemical composition parameters by introducing maleic anhydride at controlled concentrations (0.1-5 wt%) into the recycled resin system. This parameter modification alters the thermal degradation behavior of the resin, providing effective stabilization during extrusion molding without triggering the foaming reactions associated with lead-based stabilizers, thus eliminating harmful gas generation while maintaining thermal stability

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If metal frames are crimped to resin frames for easy assembly, then assembly is simplified, but disassembly for recycling becomes difficult

Engineering Contradiction:
Improveassembly easeVSAvoiddisassembly ease
Core Design Contradiction:
Ease of manufactureVSEase of repair

Solution Approach 1:

The invention applies segmentation by introducing a separable intermediate component or structural feature that divides the metal-resin connection into distinct, separable segments. This allows the frame assembly to maintain easy snap-fit assembly during manufacturing while enabling clean separation and disassembly during recycling, with the intermediate segment facilitating both assembly and subsequent dismantling without damage

Inventive Principle:
Principle #1Segmentation

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

Enhances the strength and uniformity of sashes, reduces conspicuous defects, facilitates easy disassembly for recycling, and prevents foaming, ensuring high-quality resin molded products with reduced lead content.

Implementation Method 1

the maleic anhydride improves a wettability of an interface between the recycled vinyl chloride-based resin and the wood powder

Methodology Applied
Scientific EffectWettability improvement: Wetting

Implementation Method 2

the silane coupling agent reacts with the inorganic substance

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentEP4692221A1Composition for sash, sash, and method for producing sash
Publication Date: 2026.02.11 LIXIL CORP
  • EP4692221A1 patent drawingFigure 1
  • EP4692221A1 patent drawingFigure 2
  • EP4692221A1 patent drawingFigure 3

AI summary

Provided is a composition for a sash, which contains a recycled vinyl chloride-based resin and an additive. The additive is one or more types selected from the group consisting of maleic anhydride, polytetrafluoroethylene and a silane coupling agent.