Laminated Glass Interlayer Film for Uniform Thermal Shrinkage
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Solution Overview
Problem
Interlayer films with varying heat shrinkage ratios between end and center portions lead to gaps in laminated glass, compromising safety and production efficiency.
Innovation Solution
A three or more-layer interlayer film structure with specific thermal shrinkage ratio differences controlled by adjusting polyvinyl acetal resin and plasticizer compositions, ensuring uniform shrinkage across the film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an interlayer film with high softening point is used, then the heat resistance of laminated glass is improved, but the thermal shrinkage ratio varies significantly between end and center portions causing gaps
Solution Approach 1:
The interlayer film is divided into multiple layers (first layer, second layer, third layer) with different compositions. The first and third layers contain polyvinyl acetal resin with specific plasticizers to control thermal shrinkage at surfaces, while the second layer provides different properties in the intermediate region, achieving uniform overall shrinkage while maintaining high heat resistance
Solution Approach 2:
Different layers are assigned different material compositions and plasticizer contents tailored to their specific functions. The surface layers (first and third) have optimized plasticizer content to control thermal shrinkage at the ends, while the intermediate layer (second) has different composition to balance the overall shrinkage behavior, creating local quality variations that solve the uniformity problem
2Manufacturing precision
If the thermal shrinkage ratio is reduced to prevent gaps, then the manufacturing precision is improved, but the heat resistance may be compromised
Solution Approach 1:
The invention optimizes specific parameters including plasticizer content (3-20 parts by mass per 100 parts resin), acetalization degree (60-85%), and layer thickness ratios to achieve the dual goal of reduced thermal shrinkage variation and maintained heat resistance. The softening point is controlled within 50-90°C through these parameter adjustments
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
Prevents gaps in laminated glass by minimizing thermal shrinkage ratio differences, enhancing safety and production efficiency.
Implementation Method 1
when two 5%-inside portions from both ends in the width direction of the film overall width are heated for 30 minutes at 150°C respectively, a value of the thermal shrinkage ratio
Data Source
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AI summary
There is provided an interlayer film for laminated glass with which a gap attributed to the omission of the interlayer film can be made difficult to be generated in a sheet of laminated glass. The interlayer film for laminated glass according to the present invention is an interlayer film for laminated glass having a one-layer structure or a two or more-layer structure and includes a first layer containing a thermoplastic resin, the softening point of the first layer is 60°C or more, the interlayer film has an MD direction and a TD direction, and with regard to thermal shrinkage ratios obtained when the first inside portion, the second inside portion and the central portion are heated for 2 minutes at 80°C respectively, the absolute value of the difference between the thermal shrinkage ratio MDMAX and the thermal shrinkage ratio MDMIN is less than 10%.