Multimodal Ethylene-Alpha-Olefin Interpolymer for Photovoltaic Encapsulant
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Solution Overview
Problem
Existing photovoltaic encapsulant materials face challenges in balancing curing performance and processability, as high molecular weight polymers optimize curing but low molecular weight polymers improve extrusion performance, leading to costly and inefficient solutions.
Innovation Solution
A composition comprising a multimodal ethylene/alpha-olefin interpolymer with specific properties, combined with a peroxide and a silane coupling agent, which enhances shear-thinning behavior for improved processability and curing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high molecular weight polymer is used, then curing performance is optimized, but extrusion processability deteriorates
Solution Approach 1:
The patent applies segmentation by using a multimodal molecular weight distribution with distinct peaks. The first peak (lower molecular weight, Mn1 = 10,000-50,000 g/mol) provides low viscosity for extrusion processability, while the second peak (higher molecular weight, Mn2 = 100,000-500,000 g/mol) provides high curing performance. This segmented approach allows each molecular weight fraction to fulfill its specific function independently.
Solution Approach 2:
The patent changes the molecular weight distribution parameters by specifying a multimodal distribution with controlled peak positions and ratios. The weight ratio between the lower and higher molecular weight fractions is optimized (30-70% and 70-30% respectively), and the molecular weight spread (Mw/Mn ≥ 2.0) is carefully controlled to achieve the desired balance between processability and curing performance.
2Ease of manufacture
If low molecular weight resin is used, then extrusion processability is improved, but curing efficiency deteriorates
Solution Approach 1:
The patent segments the molecular weight distribution into two distinct populations. The lower molecular weight fraction (Mn1 = 10,000-50,000 g/mol) ensures low viscosity and good extrusion processability, while the higher molecular weight fraction (Mn2 = 100,000-500,000 g/mol) provides sufficient functional groups and chain length for efficient crosslinking and curing.
Solution Approach 2:
The patent creates a composite molecular weight structure by combining two distinct polymer fractions with different molecular weight characteristics. This composite approach allows the material to exhibit both low viscosity (from the lower MW fraction) and high curing efficiency (from the higher MW fraction) simultaneously.
3Productivity
If high extrusion rate is used, then productivity is improved, but heat generation increases causing premature crosslinking
Solution Approach 1:
The patent changes the viscosity parameter by using a multimodal molecular weight distribution that results in lower overall viscosity despite the presence of high molecular weight fractions. This reduced viscosity allows for higher extrusion rates with correspondingly lower heat generation, preventing premature peroxide decomposition and crosslinking during extrusion.
4Ease of manufacture
If low viscosity resin is used, then extrusion processability is improved, but crosslinking efficiency deteriorates
Solution Approach 1:
The patent segments the polymer into two molecular weight populations where the lower MW fraction dominates the viscosity behavior (providing low viscosity for extrusion) while the higher MW fraction dominates the crosslinking behavior (providing sufficient chain length and functional groups for efficient crosslinking).
Solution Approach 2:
The patent optimizes the viscosity parameter through multimodal molecular weight distribution, achieving low viscosity at processing temperatures while maintaining adequate molecular weight for crosslinking. The specific parameter control includes Mn1 = 10,000-50,000 g/mol, Mn2 = 100,000-500,000 g/mol, and Mw/Mn ≥ 2.0.
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 composition achieves excellent shear-thinning behavior for enhanced processability and improved curing performance, allowing for higher throughput rates and efficient crosslinking, thus addressing the balance between curing and processability.
Implementation Method 1
a peroxide-based reactive curing formulation. The low crystallinity polymer provides high clarity and low modulus, while the curing formulation facilitates a crosslinking reaction, which causes the polymer to form a network
Implementation Method 2
A composition comprising a multimodal ethylene/alpha-olefin interpolymer with specific properties, combined with a peroxide and a silane coupling agent, which enhances shear-thinning behavior for improved processability
Data Source
AI summary
A composition comprising the following components a)-c): a) an alpha composition comprising a multimodal ethylene/alpha-olefin interpolymer, and wherein the alpha composition comprises the following properties: i) an Mz/Mn≥8.0, ii) a density from 0.855 to 0.890 g/cc, iii) a V100 (100° C.)≤2,000 Pa·s, iv) a V1.0 (100° C.)≥15,000 Pa·s, v) a Mn≥16,000 g/mol; b) a peroxide; and c) a silane coupling agent.