Multi-Material Contact Lens Packaging With Thermal Bonding
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Solution Overview
Problem
Existing contact lens packaging materials face challenges in being environmentally sustainable, interacting with additives, and requiring expensive specialty materials that do not thermally bond well with conventional plastics, while also needing to maintain sterility and aesthetic flexibility.
Innovation Solution
The use of injection molded packages formed from at least two thermally bondable polymer materials, where the bowl and flange are made from different polymers, allowing for a durable thermal bond without mechanical interlocks, enabling flexibility in design and sustainability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional packaging plastics like polypropylene are used for the bowl, then the package can be made from common and inexpensive materials, but the plastics can absorb additional components such as wetting agents, pharmaceuticals and nutraceuticals
Solution Approach 1:
The package base is divided into two separate components: a bowl made from non-absorptive material (cyclic olefin polymer or copolymer) that contacts the lens and solution, and a flange made from conventional plastic (polypropylene) that provides structural support. This segmentation allows each component to be optimized for its specific function without compromise.
Solution Approach 2:
Different regions of the package base are made from different materials with different properties. The bowl region has non-absorptive properties to prevent interaction with lens components, while the flange region has the mechanical properties needed for sealing and structural integrity.
2Reliability
If the bowl is made from non-absorptive materials such as cyclic olefin polymer, then the package does not absorb additional components, but such materials can be expensive and difficult to mold
Solution Approach 1:
The package is segmented into a bowl made from expensive non-absorptive material and a flange made from inexpensive conventional plastic. This allows the expensive material to be used only where necessary (in contact with lens and solution) rather than throughout the entire package.
Solution Approach 2:
The non-absorptive material property is applied locally only to the bowl region where it is needed for material compatibility, while the flange region uses standard materials that are easier and cheaper to manufacture.
3Strength
If structural interlocks are used to bond dissimilar mold materials, then good strength against lateral pull force is achieved, but the interlocks can break upon imposition of flexural stress such as would occur at the joint between bowl and flange
Solution Approach 1:
The mechanical interlock bonding system is replaced with a thermal bonding system. The flange and bowl are thermally bonded together through heating and pressing, creating a more reliable bond that can withstand flexural stress during package opening without breaking.
4Reliability
If the entire package base is made from specialty materials that do not absorb components, then compatibility with additives is ensured, but cost increases and manufacturing difficulty increases
Solution Approach 1:
The package base is segmented into a bowl made from non-absorptive specialty material and a flange made from conventional plastic. This segmentation ensures compatibility where needed while maintaining ease of manufacture for the overall package.
Solution Approach 2:
The non-absorptive material property is applied locally only to the bowl region where it contacts the lens and solution, rather than throughout the entire package base, reducing overall cost and manufacturing complexity.
5Ease of manufacture
If the flange is made from conventional plastics, then manufacturing is easier and cost is lower, but the flange cannot be made from recycled or colored materials due to interaction concerns
Solution Approach 1:
The package base is segmented into a bowl made from non-absorptive material and a flange made from conventional plastic. Since the flange does not contact the lens or solution, it can be made from recycled or colored materials without interaction concerns, increasing material selection flexibility.
Solution Approach 2:
The material selection flexibility is applied locally to the flange region, which can use recycled or colored conventional plastics, while the bowl region maintains the non-absorptive property requirement.
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 approach provides a wide range of design options for contact lens packages that are environmentally sustainable, compatible with additives, and maintain sterility and aesthetic flexibility, while avoiding the limitations of conventional materials.
Implementation Method 1
a flange comprising a bonding overlay which is durably thermally bonded to the interface tab at an interface
Data Source
AI summary
There is described a contact lens package containing a bowl for holding a contact lens and a flange around the bowl which may be made from a different polymer material than the bowl. The packages comprise at least one interface tab with at least one slot so that the second polymer material forming the flange can encapsulate the tab providing a mechanical interlock displaying good flexural strength.