Laminated Glass Interlayer Film Segmentation for Autohesion Control
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Solution Overview
Problem
Interlayer films for laminated glass face challenges in maintaining handleability and preventing autohesion, which affects their flexibility and optical clarity over time, leading to issues with mechanical strength and sound insulation performance.
Innovation Solution
A laminate structure with specific thermoplastic resin layers containing varying amounts of plasticizers, where the outer layers have a higher hydroxyl value and the inner layers have a lower hydroxyl value, along with controlled plasticizer distribution to minimize autohesion and maximize flexibility and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a plasticized polyvinyl acetal with high plasticizer content is used to improve flexibility and sound insulation performance, then the interlayer film becomes softer and more adherent, but handleability deteriorates due to autohesion when stored in roll shape
Solution Approach 1:
The patent divides the interlayer film into multiple layers with different plasticizer contents. The outer layers have lower plasticizer content (4-20 parts by mass per 100 parts resin) to maintain low autohesion and good handleability, while the inner layer has higher plasticizer content (20-40 parts by mass per 100 parts resin) to provide flexibility and sound insulation. This segmentation allows each layer to fulfill its specific function without compromising overall performance.
Solution Approach 2:
Different regions of the interlayer film are assigned different plasticizer concentrations tailored to their functional requirements. The outer layers are designed with lower plasticizer content for handling purposes, while the inner layer uses higher plasticizer content for flexibility and acoustic performance. This local differentiation of material properties resolves the contradiction between handleability and flexibility.
2Strength
If the interlayer film is made softer to improve sound insulation performance, then flexibility increases, but adherence property becomes too strong causing difficulty in handling and autohesion
Solution Approach 1:
The patent segments the interlayer film structure into outer layers and an inner layer with distinctly different plasticizer contents. The outer layers contain 4-20 parts by mass of plasticizer per 100 parts of polyvinyl acetal, maintaining low autohesion. The inner layer contains 20-40 parts by mass of plasticizer per 100 parts of polyvinyl acetal, providing flexibility. This segmentation prevents harmful autohesion while preserving desired flexibility.
Solution Approach 2:
The patent applies local quality by assigning different plasticizer concentrations to different spatial regions of the interlayer film. The outer layers have lower plasticizer content to minimize autohesion, while the inner layer has higher plasticizer content to maximize flexibility. This localized material property distribution eliminates the harmful effect of autohesion while maintaining the beneficial property of flexibility.
3Ease of operation
If a multi-layered structure with different plasticizer contents is used to balance handleability and flexibility, then both properties improve, but the structure becomes more complex
Solution Approach 1:
The patent implements a multi-layered structure segmented into outer layers and an inner layer, each with specific plasticizer contents. While this segmentation improves handleability and flexibility, it does increase structural complexity. However, the segmentation is necessary to achieve the dual objectives of low autohesion and high flexibility simultaneously.
Solution Approach 2:
The patent uses composite material construction by combining multiple layers of polyvinyl acetal resin with different plasticizer contents. This composite structure integrates the advantages of each layer: outer layers provide low autohesion for good handleability, while the inner layer provides flexibility. The composite approach allows the system to achieve properties that cannot be obtained with a single uniform material.
Data Source
AI summary
Provided is a laminate which is excellent in handleability and exhibits excellent safety performance in the case of being used as an interlayer film for safe laminated glass and in which handleability is less likely to be degraded in the case of being stored for long periods. The present invention is a laminate including a layer (1) and a layer (2) on at least one surface of the layer (1), at least one layer of outermost layers being the layer (1), the laminate having a laminated structure with three or more layers, wherein the layer (1) contains a thermoplastic resin (I), the layer (2) contains a thermoplastic resin (II) and contains 4 to 200 parts by mass of a plasticizer A with respect to 100 parts by mass of the thermoplastic resin (II), and in a case where a hydroxyl value of the plasticizer A is designated as HV(A) mgKOH/g, HV(A) ≥ 30.