Nucleated Polypropylene Resin for Contact Lens Packaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing contact lens primary packages face challenges in manufacturing efficiency, optical clarity, impermeability to storage solutions, and additive migration, which affect the maintenance of the lens and solution integrity.
Innovation Solution
A nucleated polypropylene resin formulation with a polypropylene base resin, acid scavenger, and nucleator/clarifier is developed, offering controlled shrinkage, elevated crystallization temperature, improved optical clarity, and reduced additive migration, enabling faster injection molding cycles and maintaining solution integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If non-nucleated polypropylene is used, then the crystallization temperature is lower, but the injection molding cycle time is longer and productivity is reduced
Solution Approach 1:
The patent applies parameter changes by introducing a nucleating agent that fundamentally alters the crystallization temperature parameter of polypropylene from below 110°C to above 110°C. This parameter change enables faster cooling rates and shorter injection molding cycle times while maintaining material properties, directly resolving the contradiction between crystallization temperature and productivity
Solution Approach 2:
The nucleating agent serves as an intermediary substance that facilitates the crystallization process at higher temperatures. This intermediary enables the polymer chains to organize into crystalline structures more rapidly and at elevated temperatures, thereby reducing the cooling time required and improving overall manufacturing productivity without compromising the base polypropylene material
2Device complexity
If non-nucleated polypropylene is used, then the manufacturing process is simpler, but the optical clarity is reduced
Solution Approach 1:
The nucleating agent changes the crystallization behavior parameter of the polypropylene, resulting in a finer and more uniform crystal structure. This parameter change in crystallization morphology directly improves optical clarity by reducing light scattering, while the agent itself is used in small quantities (0.01-10 wt%) to minimize formulation complexity
3Device complexity
If non-nucleated polypropylene is used, then the formulation is simpler, but the shrinkage control is less precise
Solution Approach 1:
The nucleating agent changes the crystallization temperature and rate parameters, which directly influences the shrinkage behavior of the polypropylene during cooling. By controlling when and how rapidly crystallization occurs, the agent enables more predictable and uniform shrinkage, improving manufacturing precision for dimensional accuracy in molded parts
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 nucleated polypropylene resin formulation results in shorter injection molding cycles, stiffer parts with improved optical clarity, reduced leaching of plastic constituents, and the ability to maintain solution integrity, enhancing manufacturing efficiency and product quality.
Implementation Method 1
the polypropylene resin should maintain an elevated temperature of crystallization. A particularly challenging aspect for non-nucleated materials is the lower temperature of crystallization, which results in longer injection molding cycle times
Implementation Method 2
at least one nucleator/clarifier
Data Source
AI summary
A primary package for holding contact lenses is disclosed. It is primarily made from a nucleated polypropylene resin. It has been determined that the nucleated polypropylene resin should be formulated with a polypropylene base resin with greater than 99% polypropylene homopolymer and a primary and secondary stabilizer, which also contains a catalyst acid scavenger; at least one nucleator/clarifier; and at least one catalyst acid scavenger.