High-Tg Polyvinyl Acetal Interlayer Sheet for Extrusion Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing poly(vinyl acetal) interlayers face a challenge in achieving both high glass transition temperature (Tg) and suitable flowability for extrusion, as reducing plasticizer levels to increase Tg leads to processing difficulties due to reduced flowability and increased pressure drops.
Innovation Solution
A composition comprising at least 60 wt.% poly(vinyl acetal) resin and 5 to 9 parts per hundred parts of plasticizer, with a weight average molecular weight of 160,000 or less, achieving a Tg of at least 46.0°C and a melt flow index of at least 0.65 g/10 min, allowing for extrusion at reasonable rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the amount of plasticizer is reduced to increase Tg, then the glass transition temperature is improved, but the flowability deteriorates making processing difficult
Solution Approach 1:
The patent changes the molecular weight parameter of the poly(vinyl acetal) resin to achieve the desired balance between Tg and flowability. By selecting a specific molecular weight range, the resin provides adequate flowability for extrusion processing while maintaining a high Tg of at least 46.0°C when combined with 5-9 parts per hundred parts of plasticizer.
2Temperature
If the amount of plasticizer is reduced to increase Tg, then the glass transition temperature is improved, but the pressure drop increases making processing unacceptable
Solution Approach 1:
The patent adjusts the molecular weight parameter of the poly(vinyl acetal) resin to control the pressure drop during extrusion. The selected molecular weight range ensures that the resin maintains adequate flowability and acceptable pressure drop characteristics even with reduced plasticizer content, enabling high Tg processing without unacceptable pressure increases.
3Ease of manufacture
If the molecular weight is reduced to improve flowability, then the extrusion processing is improved, but the mechanical strength may deteriorate
Solution Approach 1:
The patent optimizes the molecular weight parameter within a specific range (at least 45,000 and no more than 160,000) to achieve the desired balance between flowability and mechanical strength. This controlled molecular weight range ensures adequate extrusion processing while maintaining necessary mechanical properties for structural applications.
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 enables the production of a monolithic interlayer sheet with enhanced Tg and flowability, suitable for demanding applications, while maintaining acceptable processing conditions and extruder output.
Implementation Method 1
melt blending or melt processing the mix into a sheet by any applicable process or method known to one of skill in the art, including, but not limited to, extrusion
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A polyvinyl acetal poly(vinyl acetal), such as polyvinyl butyral, resin formulation, a method of extruding poly(vinyl acetal) resins, and related materials and products that provide for monolithic poly(vinyl acetal) sheets and glass panes having high Tg of at least 50°C and high modulus at acceptable rates as indicated by their high melt flow index. This is made possible by a reduction in the amount of plasticizer while using a low molecular weight resin not to exceed 160,000 to obtain a thermoplastic resin having a high melt flow index and high Tg. The articles made with these monolithic interlayer sheets can be used in applications that require good modulus at outdoor temperatures.