Laminated Glass End Thickness Gradient and Moisture Barrier
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Solution Overview
Problem
Laminated glass with functional films experiences peeling issues at the interface between the functional film and the intermediate bonding layer, particularly when exposed to outdoor environments, due to moisture and heat infiltration, leading to durability concerns.
Innovation Solution
A laminated glass design where the thickness of the end portion is reduced by 5 μm or more compared to the inner region, with at least one intermediate bonding layer having a moisture permeability of 50 g/m²·day or less at 40°C and 90% RH, to mitigate peeling by controlling moisture ingress and adhesive forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intermediate bonding layer is dried to reduce moisture content before production, then moisture-related deterioration of the functional film is prevented, but peeling still occurs at the interface between the functional film and intermediate bonding layer in outdoor environments
Solution Approach 1:
The patent changes the moisture permeability parameter of the intermediate bonding layer from high to low (50 g/m²·day or less), which fundamentally alters how moisture interacts with the bonding layer. This parameter change allows the layer to actively control moisture migration, preventing both moisture accumulation that causes deterioration and excessive dryness that causes peeling, thus resolving the contradiction between moisture resistance and adhesive strength
Solution Approach 2:
The patent employs a composite structure where the intermediate bonding layer combines low moisture permeability properties with specific adhesive characteristics. This composite material approach allows simultaneous achievement of moisture barrier function and sustained adhesive strength at the interface, preventing both deterioration and peeling in outdoor environments
2Strength
If the end portion thickness is reduced by 5 μm or more compared to the inner region, then peeling is suppressed through controlled reaction forces, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating a thickness gradient in the intermediate bonding layer, where the end portion has different thickness (5 μm or less reduction) compared to the inner region. This local variation in thickness allows the end portion to experience different reaction forces that suppress peeling, while the majority of the structure maintains optimal thickness for strength
Solution Approach 2:
The patent changes the geometric parameter of thickness from uniform to non-uniform, with the end portion thickness being 5 μm or less less than the inner region thickness. This parameter change creates a progressive stress distribution that reduces peak peeling forces at the vulnerable end portions, resolving the contradiction between peeling resistance and manufacturing precision
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 design effectively suppresses peeling phenomena at the interface, enhancing the long-term durability and design properties of laminated glass, particularly in outdoor applications.
Implementation Method 1
at least one of the pair of intermediate bonding layers has the following moisture permeability (A). The moisture permeability (A) indicates that a degree of moisture permeability at a temperature of 40° C. and a humidity of 90% RH measured according to JIS Z 0208: 1976 is 50 g/m2·day or less
Data Source
AI summary
There is provided a laminated glass with a functional film having good design property for a long term by suppressing a peeling at an interface between a functional film and an intermediate bonding layer. A laminated glass includes: a pair of glass plates facing each other; a pair of intermediate bonding layers brought into contact with facing surfaces of the pair of glass plates; and a functional film arranged between the pair of intermediate bonding layers, wherein a thickness measured at an end portion of the laminated glass is smaller by 5 μm or more than a thickness of the laminated glass measured at a position on the inside by 10 mm from the end portion, and at least one of intermediate bonding layers has moisture permeability (A) being a degree of moisture permeability at 40° C. and 90% RH measured by JIS Z 0208: 1976 of 50 g/m2·day or less.