Dense UHMWPE Film via Paste Processing and Biaxial Stretching
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Solution Overview
Problem
Conventional processes for ultra high molecular weight polyethylene (UHMWPE) polymers are often costly and slow due to high viscosity, and they require high solvent levels, necessitating a more efficient paste-processing method for forming dense films with superior mechanical and optical properties.
Innovation Solution
The development of a paste-processing method for UHMWPE polymers involves forming a dry, porous tape from a UHMWPE polymer with a molecular weight of at least 2,000,000 g/mol and a melt enthalpy of at least 190 J/g, which is then compressed and stretched in multiple directions above the melt temperature to produce a dense UHMWPE film with specific endotherm peaks and enhanced mechanical and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional processes (compression molding, ram extrusion, gel spinning, sintering) are used for UHMWPE, then the polymer can be processed into articles, but the processes are costly and slow due to high viscosity and require high solvent levels
Solution Approach 1:
The patent changes the processing parameters by using paste formulation with controlled solvent content (5-50% by weight) instead of conventional high solvent levels, and by controlling molecular weight (2,000,000-10,000,000 g/mol) and melt enthalpy (>190 J/g) to achieve optimal processing speed and cost efficiency
Solution Approach 2:
The patent creates a paste that replicates the processing benefits of conventional methods while avoiding their drawbacks through controlled composition, allowing the UHMWPE to be processed at lower costs and higher speeds without sacrificing product quality
2Ease of manufacture
If conventional processes are used for UHMWPE, then articles can be formed, but the processes require high solvent levels
Solution Approach 1:
The patent reduces solvent consumption by changing the formulation parameters to use only 5-50% solvent by weight in the paste, while maintaining process feasibility through controlled molecular weight and melt enthalpy characteristics of the UHMWPE polymer
3Productivity
If conventional processes are used for UHMWPE, then articles can be produced, but the processes are costly
Solution Approach 1:
The patent reduces manufacturing cost by optimizing paste composition with controlled solvent levels (5-50%) and selecting UHMWPE with specific molecular weight (2,000,000-10,000,000 g/mol) and melt enthalpy (>190 J/g), which enables faster processing and lower operational costs
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
This method results in dense UHMWPE films with high tensile strength, excellent barrier properties, optical uniformity, low haze, and transparency, while also reducing processing costs and time compared to conventional methods.
Implementation Method 1
a first endotherm from about 135° C. to about 143° C.; and a second endotherm from about 145° C. to about 155° C.
Implementation Method 2
a first endotherm from about 135° C. to about 143° C.; and a second endotherm from about 145° C. to about 155° C.
Implementation Method 3
paste-processed ultra high molecular weight polyethylene expanded into dense articles
Data Source
AI summary
Paste-processed ultra high molecular weight polyethylene (UHMWPE) polymers, and processes for the formation of dense UHMWPE films from a highly crystalline ultra high molecular weight polyethylene polymer are provided. The UHMWPE films described herein may be manufactured by 1) compressing a dry, porous UHMWPE tape and then stretching above the melt temperature of the UHMWPE polymer; 2) expanding a dry, porous UHMWPE tape above the melt of the UHMWPE polymer without compression; or 3) expanding a dry, porous UHMWPE tape below the melt of the UHMWPE polymer to form a porous membrane and subsequently compressing the porous membrane at temperatures above the melt of the UHMWPE polymer to forma dense film. This dense film may be further stretched biaxially to enhance the properties of the dense film.