Laminated Glass Interlayer Film Recesses Prevent Autohesion

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Solution Overview

Problem

Interlayer films for laminated glass tend to adhere to each other (autohesion) during storage, making them difficult to peel apart, even after being stacked in a controlled environment.

Innovation Solution

The interlayer film is designed with a large number of recesses on at least one surface, featuring an arithmetical mean height Sa of 200 nm or more, which reduces autohesion and allows for easy peeling without the need for mechanical assistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If interlayer films are stacked for storage, then storage efficiency is improved, but autohesion occurs making peeling difficult

Engineering Contradiction:
Improvestorage efficiencyVSAvoidpeeling ease
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent applies preliminary action by forming recesses on the interlayer film surface before stacking. This pre-formed surface structure prevents autohesion from occurring during storage, allowing films to be stacked efficiently while maintaining easy peelability when needed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by creating recesses at specific locations on the interlayer film surface rather than modifying the entire surface uniformly. This localized surface modification maintains necessary adhesion in contact areas while preventing autohesion in recessed areas, resolving the contradiction between storage efficiency and peeling ease.

Inventive Principle:
Principle #3Local quality

2Reliability

If recesses are formed on interlayer film surface, then deaeration properties are improved, but autohesion increases during storage

Engineering Contradiction:
Improvedeaeration propertiesVSAvoidpeeling ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies parameter changes by carefully controlling the depth, width, and distribution of recesses to achieve an optimal balance. The recess parameters are designed to provide sufficient deaeration channels during lamination while limiting autohesion during storage, resolving the contradiction between these two requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating recesses with specific dimensional characteristics at particular locations on the film surface. This localized structuring provides deaeration functionality where needed while maintaining appropriate surface properties for controlled autohesion behavior during storage.

Inventive Principle:
Principle #3Local quality

3Area of stationary object

If interlayer films are stacked closely for efficient storage, then storage space utilization is improved, but autohesion between films occurs

Engineering Contradiction:
Improvestorage space utilizationVSAvoidautohesion
Core Design Contradiction:
Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-forming recesses on the film surface before stacking operations. This preliminary surface structuring prevents autohesion from developing during close-stack storage, enabling high space utilization without the harmful effect of film adhesion.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by creating recesses that locally modify surface properties. These recessed areas prevent contact and adhesion between stacked films while maintaining necessary film integrity and adhesion in non-recessed areas, allowing efficient storage without autohesion.

Inventive Principle:
Principle #3Local quality

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 solution ensures excellent deaeration properties during the production of laminated glass and prevents autohesion, allowing the interlayer films to be easily peeled apart even after storage, thereby improving manufacturing efficiency.

Implementation Method 1

The surface having the recesses has an arithmetical mean height Sa of 200 nm or more as measured in conformity with ISO 25178... When the pattern of protrusions and recesses on the surface of each interlayer film for a laminated glass is controlled such that the Sa value is 200 nm or more, the resulting interlayer films are easily peelable without autohesion even after storage in a stacked state.

Methodology Applied
Scientific EffectSurface roughness:

Implementation Method 2

In the process for producing a laminated glass, deaeration properties upon stacking a glass plate and an interlayer film for a laminated glass on top of each other is important. The interlayer film for a laminated glass therefore commonly has a large number of recesses formed on at least one surface for the purpose of ensuring the deaeration properties in production of a laminated glass.

Methodology Applied
Scientific EffectDeaeration:

Data Source

PatentEP3851275B1Interlayer for laminated glass, laminated glass, and production method for interlayer for laminated glass
Publication Date: 2025.03.05 SEKISUI CHEMICAL CO LTD
  • EP3851275B1 patent drawingFigure 1~3
  • EP3851275B1 patent drawingFigure 4~5
  • EP3851275B1 patent drawingFigure 6(a)~7

AI summary

The present invention provides an interlayer film for a laminated glass which is easily peelable without autohesion even after storage in a stacked state, a laminated glass prepared using the interlayer film for a laminated glass, and a method for producing the interlayer film for a laminated glass. The present invention provides an interlayer film for a laminated glass, having a large number of recesses on at least one surface, the at least one surface having the recesses having an arithmetical mean height Sa of 200 nm or more as measured in conformity with ISO 25178.