Wedge-Shaped Polyvinyl Acetal Interlayer Film for Laminated Glass
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Solution Overview
Problem
Wedge-shaped interlayer films for laminated glass tend to generate wrinkles, leading to poor appearance issues when rolled and used in laminated glass production, especially during heating processes.
Innovation Solution
An interlayer film with a specific configuration, including a polyvinyl acetal resin and a controlled thermal shrinkage ratio, is developed, featuring a wedge angle between 0.01 mrad and 2 mrad, and a thickness gradient to minimize thermal shrinkage differences, thereby reducing wrinkle formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a wedge-shaped interlayer film is used to suppress double images in head-up displays, then the visibility for drivers is improved, but wrinkles are easily generated during rolling and heating processes leading to poor appearance
Solution Approach 1:
The invention changes the thermal shrinkage ratio parameter of the polyvinyl acetal resin to be 30% or less at 150°C, and controls the wedge angle to be 0.1° or less. These parameter changes allow the interlayer film to maintain wedge shape for suppressing double images while reducing differential thermal shrinkage that causes wrinkles during heating and rolling processes.
Solution Approach 2:
The invention uses a composite material system consisting of polyvinyl acetal resin combined with specific additives including silane-modified polyethylene crosslinking agent, metal salt catalyst, and hydroquinone monomethyl ether. This composite material composition enables controlled thermal shrinkage and crosslinking that prevents wrinkle formation while maintaining the wedge shape functionality.
2Manufacturing precision
If the thermal shrinkage ratio is reduced to suppress wrinkles, then the appearance quality is improved, but the heat shrinkage properties may affect the lamination process
Solution Approach 1:
The invention optimizes the thermal shrinkage ratio parameter to be 30% or less at 150°C, which is sufficiently low to prevent wrinkles during lamination and heating processes while still allowing adequate shrinkage for proper bonding and conformability during the lamination process.
Solution Approach 2:
The invention applies preliminary crosslinking action by incorporating silane-modified polyethylene and metal salt catalyst that activate during the lamination heating process. This preliminary crosslinking strengthens the interlayer film before final heating, preventing wrinkles while ensuring reliable lamination bonding.
3Illumination intensity
If the wedge angle is increased to improve double image suppression, then the head-up display performance is enhanced, but the difference in thickness between ends increases causing more wrinkles
Solution Approach 1:
The invention changes the wedge angle parameter to be 0.1° or less, which provides sufficient double image suppression for head-up display functionality while minimizing the thickness difference between ends of the interlayer film, thereby reducing the tendency to generate wrinkles during rolling and heating.
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 suppresses wrinkle generation in the interlayer film and laminated glass, ensuring a better appearance and preventing poor outcomes during both rolling and heating processes.
Implementation Method 1
the absolute value of a difference between the largest thermal shrinkage ratio among three thermal shrinkage ratios of a first thermal shrinkage ratio at 150°C in the MD direction on a first position apart from the one end by 0.05X toward the other end, a second thermal shrinkage ratio at 150°C in the MD direction on a second position apart from the one end by 0.5X toward the other end, and a third thermal shrinkage ratio at 150°C in the MD direction on a third position apart from the one end by 0.95X toward the other end and the smallest thermal shrinkage ratio among the three thermal shrinkage ratios is less than 15%
Data Source
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AI summary
There is provided an interlayer film for laminated glass enabling laminated glass in which a poor appearance is suppressed to be obtained because wrinkles are hardly generated in the interlayer film. The interlayer film for laminated glass according to the present invention has an MD direction and a TD direction and has one end and the other end being at the opposite side of the one end and having a thickness thicker than the one end, the one end and the other end are respectively positioned at both sides in the TD direction of the interlayer film, and when a distance between the one end and the other end is defined as X, the absolute value of a difference between the largest thermal shrinkage ratio among three thermal shrinkage ratios of the first thermal shrinkage ratio at 150°C in the MD direction on a first position apart from the one end by 0.05X toward the other end, the second thermal shrinkage ratio at 150°C in the MD direction on a second position apart from the one end by 0.5X toward the other end, and the third thermal shrinkage ratio at 150°C in the MD direction on a third position apart from the one end by 0.95X toward the other end and the smallest thermal shrinkage ratio among the three thermal shrinkage ratios is 5% or less.