Sealed Switchable Glazing Plasticizer Barrier

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Solution Overview

Problem

Functional films in vehicle glazings, such as suspended particle device (SPD) and liquid crystal (LCD) films, are prone to damage due to plasticizer migration from adhesive interlayer films, leading to aesthetic issues and potential delamination, with existing solutions either requiring plasticizer-free interlayers or barrier layers that cause thickness variations and stress.

Innovation Solution

A sealing member comprising a strip of polymer film with adhesive regions on either edge and an adhesive-free region coincident with the active layer, preventing plasticizer ingress and egress, is applied to the edges of the functional film, ensuring a secure and stress-free laminated structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plasticizer-free or low-plasticizer content adhesive interlayer film is used, then plasticizer migration into the active layer is prevented, but the choice of adhesive interlayer material is limited and manufacturing complexity increases

Engineering Contradiction:

Improvefunctional film integrityVSAvoidadhesive interlayer material selection

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The adhesive interlayer film is segmented into distinct regions: adhesive regions at the edges for bonding, and a central adhesive-free region that contacts the active layer. This segmentation allows the interlayer to provide both adhesive functionality and barrier functionality simultaneously, resolving the contradiction between reliability and material selection flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the adhesive interlayer film have different properties: the edge regions contain adhesive material for bonding, while the central region is adhesive-free to prevent plasticizer migration. This local differentiation allows the same interlayer to satisfy both bonding requirements and protection requirements without limiting material choices.

Inventive Principle:

Principle #3Local quality

2Reliability

If a barrier layer is positioned around the periphery of the functional film, then plasticizer ingress is prevented, but local thickness variation is created causing stress and delamination

Engineering Contradiction:

Improveplasticizer barrier effectivenessVSAvoidlaminated glazing uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The central adhesive-free region of the interlayer film serves multiple functions simultaneously: it acts as a barrier to plasticizer migration, provides uniform thickness across the functional film area, and maintains structural integrity. This multi-functionality resolves the contradiction between barrier effectiveness and compositional stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If the adhesive interlayer film contacts the active layer, then a continuous laminated structure is formed, but plasticizer components migrate into the active layer causing damage

Engineering Contradiction:

Improvelaminated structure continuityVSAvoidplasticizer migration damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The interlayer film is segmented into adhesive edge regions for structural bonding and a central adhesive-free region that contacts the active layer. This segmentation creates a protective barrier zone that prevents plasticizer migration while maintaining continuous lamination through the adhesive regions, resolving the contradiction between structure continuity and harmful factor prevention.

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

The solution effectively prevents plasticizer migration, maintaining the integrity and functionality of the functional film, reducing the risk of delamination and aesthetic issues, while allowing the use of any adhesive interlayer material, and ensuring minimal thickness variation in the laminated glazing.

Implementation Method 1

a first strip-like region of adhesive material adjacent a first edge of the strip of polymer film material, and a second strip-like region of adhesive material adjacent a second edge of the strip of polymer film material

Methodology Applied

Scientific EffectAdhesive: Adhesive

Implementation Method 2

the adhesive-free region is positioned coincident with the active layer of the functional film... physically prevent the ingress of any plasticizer components into the active layer

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentUS8551603B2Sealed switchable glazing

Publication Date: 2013.10.08 PILKINGTON GRP LTD

AI summary

The invention discloses a functional film assembly comprising a functional film having at least one active layer laminated between first and second planar electrode layers. At least a portion of the edge region of the functional film is sealed by a sealing member. Preferably, the sealing member comprises a strip of polymer film material having on one surface a first strip-like region of adhesive material adjacent a first edge of the strip of polymer film material, and a second strip-like region of adhesive material adjacent a second edge of the strip of polymer film material. There is an adhesive-free region between the first and second strip-like regions of adhesive material, which is positioned coincident with the active layer of the functional film.