Shellac Thermoplastic Lens Blocking Material
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Solution Overview
Problem
Existing lens blocking materials, such as low temperature fusible metal alloys, pose environmental and health hazards due to toxicity and require improvement for safer, more efficient use in securing lens blanks during machining operations.
Innovation Solution
A thermoplastic material formulated with shellac and a plasticizer, having a softening point between 60° C. and 85° C., is used for blocking optical substrates, allowing for easier handling and reduced heat requirements, with the thermoplastic material being hard enough to maintain shape during processing and soft enough to facilitate secure docking without sharp transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low temperature fusible metal alloys are used for lens blocking, then the blocking material eliminates messiness and enables reusability, but the material causes environmental and health hazards due to toxicity from metals like cadmium, lead and bismuth
Solution Approach 1:
The patent changes the chemical composition parameters of the blocking material from toxic metal alloys to non-toxic organic compounds. Specifically, it uses compounds with melting points between 60-85°C that are non-toxic and environmentally safe, fundamentally altering the material's chemical properties while maintaining the desired reusability and blocking functionality
Solution Approach 2:
The patent describes blocking compositions that can be used once and then discarded without environmental harm, or that can be melted down and reused. The material is designed to be inexpensive and non-toxic, allowing for disposable use or easy reclamation without health hazards, replacing the need for complex reclamation processes required for toxic metal alloys
2Duration of action of stationary object
If powdered or particulate metals are subjected to sintering and heat treating to formulate alloys, then the blocking material can be reused, but fumes and dust particles are released creating environmental and health hazards
Solution Approach 1:
The patent replaces the mechanical sintering process used for metal alloys with a thermal melting process for organic compounds. Instead of mechanically mixing and sintering powdered metals, the organic blocking composition is simply melted at 60-85°C and then solidified, eliminating the generation of harmful fumes and dust particles while maintaining reusability through melting and re-solidification
Solution Approach 2:
The patent changes the processing temperature parameter from high-temperature sintering of metals to low-temperature melting of organic compounds (60-85°C). This parameter change eliminates the generation of harmful fumes and dust particles while still enabling the material to be reused by melting and re-solidification
3Use of energy by moving object
If thermoplastic materials with low melting points are used for lens blocking, then the heat requirements are reduced, but the material may be too soft and difficult to handle during processing
Solution Approach 1:
The patent optimizes the melting point parameter to a specific range of 60-85°C, which is high enough to maintain material rigidity and ease of handling during processing, yet low enough to reduce heat requirements compared to traditional metal alloys. This parameter optimization resolves the contradiction between softness and handleability
Solution Approach 2:
The patent uses composite organic blocking compositions containing multiple components (e.g., waxes, resins, polymers) that work together to provide both low melting point and adequate structural integrity. The composite nature allows the material to be soft enough for easy blocking but firm enough for handling during machining operations
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 thermoplastic material provides a safer, non-toxic, and environmentally friendly solution for lens blocking, reducing heat requirements and stress on optical substrates, while enhancing cosmetic and optical properties, and allowing for easier deblocking and handling.
Implementation Method 1
a thermoplastic material formulated from a composition comprising a shellac and a plasticizer where the shellac and the plasticizer are chosen so as to have the softening point of the thermoplastic material greater than or equal to 60° C. and smaller than or equal to 85° C.
Implementation Method 2
the softening point of the thermoplastic material greater than or equal to 60° C. and smaller than or equal to 85° C.
Data Source
AI summary
Use of a thermoplastic material for blocking an optical substrate (100) in a machining position, wherein the thermoplastic material is formulated from a composition comprising a shellac and a plasticizer where the shellac and the plasticizer are chosen so as to have the softening point of the thermoplastic material greater than or equal to 60° C. and smaller than or equal to 85° C.