Laminated Glass Interlayer with Variable Roughness for Bubble Reduction
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Solution Overview
Problem
Conventional wedge-shaped interlayer films for laminated glass often experience poor degassing, leading to air bubbles between the glass plates, which results in a poor appearance and hindered visibility of displayed information in head-up displays, especially in automotive applications.
Innovation Solution
An interlayer film with a thermoplastic resin, specifically polyvinyl acetal resin, having varying thicknesses and surface roughness values, and a wedge-like sectional shape, is used to minimize air bubble formation by ensuring proper contact and degassing during the lamination process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a wedge-shaped interlayer film is used to suppress double images in HUD, then the visibility of displayed information is improved, but air bubbles are likely to be left behind between glass plates and the interlayer film
Solution Approach 1:
The interlayer film has different surface roughness values at different positions (first surface has Rz1 of 10-30μm, second surface has Rz2 of 5-25μm), creating local quality variations that improve contact with glass plates at critical areas while maintaining the wedge shape for HUD functionality. This resolves the contradiction by making the film locally adaptive rather than uniformly structured.
Solution Approach 2:
The invention changes the surface roughness parameter (Rz) to specific ranges (10-30μm for first surface, 5-25μm for second surface) while maintaining the wedge shape. This parameter optimization enables better air bubble evacuation during lamination while preserving the double image suppression capability, thus resolving the reliability-visibility contradiction.
2Shape
If the surface of the interlayer film is made smooth, then the appearance of laminated glass is improved, but air bubbles are more likely to be trapped between the glass plates and the interlayer film
Solution Approach 1:
The interlayer film has different surface roughness values at different positions (first surface has Rz1 of 10-30μm, second surface has Rz2 of 5-25μm), creating local quality variations that improve contact with glass plates at critical areas while maintaining the wedge shape for HUD functionality. This resolves the contradiction by making the film locally adaptive rather than uniformly structured.
Solution Approach 2:
The invention changes the surface roughness parameter (Rz) to specific ranges (10-30μm for first surface, 5-25μm for second surface) while maintaining the wedge shape. This parameter optimization enables better air bubble evacuation during lamination while preserving the double image suppression capability, thus resolving the reliability-visibility contradiction.
3Illumination intensity
If the wedge angle of the interlayer film is increased to improve double image suppression, then the visibility in HUD is improved, but the likelihood of air bubble formation increases
Solution Approach 1:
The interlayer film has different surface roughness values at different positions (first surface has Rz1 of 10-30μm, second surface has Rz2 of 5-25μm), creating local quality variations that improve contact with glass plates at critical areas while maintaining the wedge shape for HUD functionality. This resolves the contradiction by making the film locally adaptive rather than uniformly structured.
Solution Approach 2:
The invention changes the surface roughness parameter (Rz) to specific ranges (10-30μm for first surface, 5-25μm for second surface) while maintaining the wedge shape. This parameter optimization enables better air bubble evacuation during lamination while preserving the double image suppression capability, thus resolving the reliability-visibility contradiction.
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3~6
AI summary
There is provided an interlayer film for laminated glass with which an air bubble can be made difficult to be left behind between a lamination glass member and the interlayer film when laminated glass is obtained. The interlayer film for laminated glass according to the present invention contains a thermoplastic resin 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, each of three values of the ten-point average roughness Rz of the surface at a position apart from the one end by 50 mm toward the other end, the ten-point average roughness Rz of the surface at a center position between the one end and the other end, and the ten-point average roughness Rz of the surface at a position apart from the other end by 50 mm toward the one end is 20 µm or more, and a value calculated by subtracting the smallest value among the three values from the largest value among the three values is 3 µm or more and 9 µm or less.