Biaxially Stretched Polyester Film Decarboxylation Catalyst
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Solution Overview
Problem
Biaxially stretched polyester films used in electrical insulation applications face challenges due to high hydrolysis tendencies and increased costs associated with achieving low carboxyl end group contents, which affect their service life and processing difficulties, especially when regrind materials are reused.
Innovation Solution
A biaxially stretched film comprising predominantly polyester with a copper salt and halide, where the molar ratio of halide to copper is between 0.5 and 3.5, is developed, incorporating a decarboxylation catalyst system to reduce hydrolysis rates and maintain good electrical insulation properties, even when using self-regenerated materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-condensation is used to reduce carboxyl end group content, then hydrolysis resistance is improved, but processing difficulty increases due to high viscosity
Solution Approach 1:
The patent changes the chemical parameter of carboxyl end group content through decarboxylation reaction, reducing it from typical levels to below 15 meq/kg. This parameter change enables both low hydrolysis rates and acceptable processing conditions by eliminating the need for extreme viscosity increases that would make processing difficult
Solution Approach 2:
The patent converts the harmful carboxyl end groups into a benefit by using them as substrates for decarboxylation reaction. The carboxyl groups that cause hydrolysis are transformed through catalytic decarboxylation, removing the harmful effect while maintaining polymer integrity and enabling low hydrolysis rates without compromising processability
2Ease of manufacture
If regrind material is reused to reduce costs, then manufacturing cost is reduced, but hydrolysis tendency increases due to increased carboxyl end group content
Solution Approach 1:
The patent enables the polyester film production system to self-regenerate low carboxyl end group material through the decarboxylation catalyst system. Even when regrind material with higher carboxyl content is reused, the catalyst continuously reduces carboxyl groups during processing, allowing unlimited regrind reuse while maintaining low hydrolysis rates and consistent product quality
Solution Approach 2:
The patent recovers value from what would normally be waste or low-value regrind material by using the decarboxylation catalyst to convert high carboxyl-content regrind back into low carboxyl-content polyester suitable for continued use. This recovery process eliminates the need to discard regrind or blend it with expensive virgin material
3Reliability
If high viscosity is achieved to reduce carboxyl end groups, then hydrolysis rate is reduced, but power consumption increases and shear heat formation occurs
Solution Approach 1:
The patent replaces the mechanical/physical approach of increasing viscosity to reduce carboxyl end groups with a chemical approach using catalytic decarboxylation. Instead of relying on high viscosity and extended residence time, the copper salt catalyst chemically removes carboxyl groups at lower viscosities, significantly reducing power consumption and eliminating excessive shear heat formation
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 film exhibits reduced hydrolysis rates, improved electrical insulation properties, and cost-effectiveness, suitable for long-term use in applications like solar module backside laminates, with dielectric strength of at least 100 kV/mm and minimal increase in hydrolysis when using up to 50% self-regenerated material.
Implementation Method 1
a biaxially stretched film consisting predominantly of a polyester containing at least one copper salt and one halide... which is based on a decarboxylation reaction and not on reactive endcapping with an end group remaining in the product
Data Source
AI summary
Biaxially stretched film comprises polymer components, at least one copper salt and a halide, where the: film has a dielectric strength in alternating current at 23[deg] C and 50 Hz of at least 100 kV/mm; and the polymer components are predominantly polyester. Independent claims are included for: (1) the preparation of the film comprising extruding a melt to a single layer of the film through a flat nozzle, drawing or deterring the obtained film for the solidification of one or more rolls (cool rolls) as an amorphous prefilm, heating the film, biaxially stretching the film, thermofixing the biaxially stretched film and subsequently rolling the film; and (2) a laminate comprising the film and at least one further film.