Cyclic Aldehyde Polyvinyl Acetal Interlayers for Low-Haze Recycling
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Solution Overview
Problem
The recycling of multilayer polyvinyl butyral (PVB) interlayers is hindered by the inability to re-extrude scrap materials due to differences in composition between skin and core layers, resulting in high haze and unacceptable visual quality, preventing large-scale recycling.
Innovation Solution
A polyvinyl acetal resin composition is developed, incorporating residues of cyclic aldehydes and C3 to C8 aliphatic aldehydes, with a modified polyvinyl acetal resin blended with plasticizers to form interlayers that can be recycled, reducing haze and enabling re-extrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multilayer interlayers are produced with different polyvinyl butyral compositions in skin and core layers, then enhanced sound insulation is achieved, but the interlayers cannot be recycled due to high haze when re-extruded
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyvinyl acetal resin by incorporating cyclic aldehyde residues (such as furfural) alongside conventional aliphatic aldehydes. This parameter change in resin composition enables the core layer to be chemically compatible with skin layers, allowing multilayer scrap to be re-extruded with acceptable haze levels and enabling recycling while maintaining sound insulation performance
Solution Approach 2:
The patent creates a composite resin system by combining polyvinyl alcohol with both cyclic aldehydes (e.g., furfural) and conventional aliphatic aldehydes (e.g., butyraldehyde). This composite approach produces a core layer resin that maintains the functional benefits of multilayer construction while enabling compatibility for recycling through controlled composition blending
2Ease of manufacture
If conventional polyvinyl butyral resins are used in multilayer interlayers, then production is simplified, but scrap materials exhibit high haze and are unacceptable for visual quality when re-extruded
Solution Approach 1:
The patent changes the chemical parameters of the polyvinyl acetal resin by introducing cyclic aldehyde components (1-30 weight percent of cyclic aldehyde residues) to the conventional composition. This parameter modification enables the resin to maintain visual quality (haze < 5%) when multilayer scrap is re-extruded, while preserving production simplicity through a single extrusion process
3Reliability
If multilayer interlayers with different resin compositions are produced, then enhanced acoustic performance is achieved, but large scale recycling cannot be successfully achieved
Solution Approach 1:
The patent modifies the resin composition parameters to include cyclic aldehyde residues (furfural, thiophene-2-carboxaldehyde, pyridine-2-carboxaldehyde) in combination with conventional aliphatic aldehydes. This parameter change enables the core layer to be chemically compatible with skin layers, allowing multilayer scrap to be re-extruded with acceptable optical properties and enabling large-scale recycling while maintaining acoustic performance
Solution Approach 2:
The patent creates a universal resin composition that serves multiple functions: it provides the acoustic performance enhancement of multilayer construction, maintains visual quality for consumer acceptance, and enables recyclability for environmental sustainability. The cyclic aldehyde-modified polyvinyl acetal resin acts as a multi-functional material that resolves the contradiction between performance and recyclability
Data Source
AI summary
A modified polyvinyl acetal resin comprising residues of a cyclic aldehyde is provided for use in forming interlayers for making laminated glass. Interlayers as described herein exhibit desirable optical and acoustic properties and are more easily recycled than those without the modified polyvinyl acetal resin.