Multi-layer Foam Sheet Sagging Reduction
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Solution Overview
Problem
Conventional multi-layer foam sheets used as interleaf sheets for glass plates in liquid crystal panels are prone to sagging, which complicates handling and vacuum suction processes, especially as glass plates become larger and thinner, requiring a thinner, lighter, and more stable foam sheet with enhanced cushioning and antistatic properties.
Innovation Solution
A multi-layer foam sheet with a polyethylene-based resin foam layer and fusion-laminated antistatic layers on both sides, comprising low-density polyethylene, polystyrene-based resin, styrenic elastomer, and polymeric antistatic agent, with specific weight percentages and melt flow rates, to achieve a sandwich structure that maintains stiffness and reduces sagging while providing excellent cushioning and antistatic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the foam sheet thickness is reduced to meet the demand for thinner interleaf sheets, then the weight and apparent density decrease, but the cushioning property deteriorates
Solution Approach 1:
The patent applies composite materials by combining polyethylene-based resin foam with anti-static resin layers to create a multi-layer structure. This composite construction allows the thin foam sheet (50-200 μm) to maintain adequate cushioning properties while adding anti-static functionality, as the combination of materials provides both mechanical protection and electrostatic control without requiring increased thickness
2Weight of moving object
If the foam sheet thickness is reduced, then the weight decreases, but the degree of sag when cantilever-supported increases
Solution Approach 1:
The multi-layer composite structure combining foam material with anti-static resin layers provides enhanced structural stability. The composite construction maintains low weight while reducing sagging behavior through the combined properties of the layered materials, achieving better handling characteristics than conventional single-layer foam sheets
3Strength
If conventional foam sheets are used, then the cushioning property is sufficient, but the antistatic property is inadequate leading to static charge accumulation and dust deposition
Solution Approach 1:
The patent applies multi-functionality by designing the anti-static resin layers to simultaneously provide anti-static protection and enhance cushioning properties. The anti-static resin layers contain antistatic agents that prevent static charge accumulation and dust deposition, while the layered structure itself contributes to the overall cushioning performance, making the interleaf sheet perform multiple functions without requiring separate components
4Strength
If the foam sheet shows high degree of sag, then the cushioning property is maintained, but the handling property deteriorates and vacuum suction efficiency decreases
Solution Approach 1:
The composite multi-layer structure improves handling properties and vacuum suction efficiency while maintaining cushioning performance. The combination of foam layers and anti-static resin layers creates a structure that is easier to handle and removes more efficiently under vacuum suction, eliminating the need for excessive thickness that would cause sagging and handling difficulties
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 multi-layer foam sheet exhibits improved stiffness, reduced sagging, and enhanced handling properties, allowing for efficient vacuum suction and use as an interleaf sheet for large and thin glass plates, while maintaining sufficient cushioning and antistatic properties to prevent static charge accumulation and dust deposition.
Implementation Method 1
the foam layer is constituted of a polyethylene-based resin and because each of the antistatic layers is in the form of a thin film, the multi-layer foam sheet has excellent cushioning property
Implementation Method 2
each of the antistatic layers contains a polymeric antistatic agent and shows excellent antistatic property, the multi-layer foam sheet of the present invention does not easily get accumulated with static charges
Implementation Method 3
an anti-static layer that is fusion-laminated by coextrusion on each of both sides of the foam layer
Data Source
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AI summary
A multi-layer foam sheet with an apparent density of 30 to 300 kg/m3 and a thickness of 0.05 to 2 mm, including a foam layer containing a polyethylene-based resin (A), and an antistatic layer fusion-laminated by coextrusion on each of both sides of the foam layer. The antistatic layer has a basis weight of 1 to 10 g/m2 and contains a polyethylene-based resin (B), a polystyrene-based resin, a styrenic elastomer, and a polymeric antistatic agent, with the polystyrene-based resin being contained in the antistatic layer in an amount of 15 to 70% by weight.