Single-Site Polyolefin Sheets With Low Die Lip Buildup
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Solution Overview
Problem
Existing polyolefin sheets face challenges in achieving desired properties while facilitating easy manufacturing without adversely affecting them, particularly due to issues like die lip buildup and organoleptic problems caused by low molecular weight species and wax, and lack of temperature resistance.
Innovation Solution
A polymer sheet comprising greater than 90 wt.% of single-site catalyzed polyolefin, with minimal wax and low molecular weight species, offering superior physical properties and temperature resistance, suitable for applications such as lightweighting and food packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional polyolefin sheets with low molecular weight species and wax are used, then processing is easier, but die lip buildup increases and production downtime increases
Solution Approach 1:
The patent extracts and removes low molecular weight species and wax from the polyolefin composition through controlled polymerization processes, eliminating the source of die lip buildup while maintaining processability of the remaining high molecular weight polymer matrix
Solution Approach 2:
The patent changes the molecular weight distribution parameters by using single-site catalysts to produce polymers with narrow molecular weight distributions and high molecular weights, fundamentally altering the polymer's processing behavior to reduce die lip accumulation
2Weight of moving object
If thin polymer sheets are used for lightweighting, then weight reduction is achieved, but temperature resistance decreases
Solution Approach 1:
The patent creates a composite-like structure within the single polymer material by combining high molecular weight polyolefin with specific additives and using multi-layer coextrusion techniques to achieve both thin gauge and high temperature resistance in the final sheet product
Solution Approach 2:
The patent changes the thermal properties by controlling the polymer's molecular architecture and crystallinity through single-site catalysis, enabling thin sheets to maintain high melting points and temperature resistance unlike conventional thin polyethylene sheets
3Strength
If single-site catalyzed polyolefin with high molecular weight is used, then temperature resistance and physical properties improve, but processing difficulty increases
Solution Approach 1:
The patent applies local quality by using different catalyst systems and processing conditions for different portions of the polymer production process, optimizing each stage to balance molecular weight buildup with processability requirements
Solution Approach 2:
The patent introduces intermediary substances such as process oils and lubricants that facilitate the processing of high molecular weight single-site catalyzed polyolefins by reducing friction and improving flow characteristics during extrusion and forming operations
Data Source
AI summary
Thin polymer sheets and used thereof are described. A polymer sheet can include greater than 90 wt. % of a single-site catalyzed polyolefin (PO) and have a thickness of at least 0.0254 cm. The sheet can be used to produce molded articles.