Extruded Plastic Sheet Strain Suppression
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Solution Overview
Problem
Plastic eyeglass lenses and helmet shields produced by injection molding often have high strain, leading to eye strain, headaches, and increased susceptibility to cracking, making them difficult to wear for extended periods and process effectively.
Innovation Solution
A thin sheet with suppressed strain is achieved by subjecting specific plastics to extrusion molding, followed by vacuum or air-pressure forming, using resins like polyamide, polycarbonate, cellulose acrylate, and acrylic resins, with alicyclic polyamide resins and specific repeating units, to produce sheets with low retardation and haze values, ensuring excellent transparency and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If injection molding is used to produce plastic lenses or shields, then the production efficiency is improved, but the strain in the product increases
Solution Approach 1:
The patent changes the molding method parameter from injection molding to extrusion molding. This parameter change fundamentally alters the flow pattern and stress distribution during forming, resulting in significantly reduced strain in the final product while maintaining production efficiency. The extrusion process allows plastic to flow more uniformly through the mold, avoiding the high-speed narrow passage flow that causes strain in injection molding.
2Weight of moving object
If the lens or shield is made thinner to improve aesthetics and weight, then the visibility and comfort are improved, but the strain increases and cracking susceptibility increases
Solution Approach 1:
The patent changes the molding method from injection molding to extrusion molding, which fundamentally alters how stress is distributed during forming. This parameter change enables production of thin lenses and shields with uniformly distributed low strain, preventing stress concentration that would lead to cracking. The extrusion process maintains structural integrity even at reduced thickness by avoiding the high-speed flow through narrow passages that creates strain in injection molding.
3Speed
If injection molding is used to produce thin lenses, then the production speed is improved, but the strain and eye discomfort increase
Solution Approach 1:
The patent changes the molding method parameter from injection molding to extrusion molding. This parameter change maintains production speed while fundamentally reducing the strain in the final product. The extrusion process allows plastic to flow more gradually and uniformly, avoiding the high-speed narrow passage flow that causes strain, thereby eliminating eye strain and headaches caused by high-strain lenses.
4Ease of manufacture
If injection molding is used to produce lenses or shields, then the manufacturing capability is improved, but the processability and yield decrease due to cracking
Solution Approach 1:
The patent changes the molding method from injection molding to extrusion molding, which fundamentally improves the strain distribution in the final product. This parameter change enhances processability by reducing strain-induced cracking during subsequent processing operations. The uniformly distributed low strain in extrusion-molded products allows for better handling, machining, and assembly, thereby improving yield and reducing waste.
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 resulting sheets are lightweight, comfortable to wear, resistant to cracking, and suitable for eyeglasses, helmets, and medical shields, offering improved visibility and durability while reducing eye strain and processing issues.
Implementation Method 1
subjecting a plastic containing at least one resin selected from polyamide resins, polycarbonate resins, cellulose acylate resins, and acrylic resins to extrusion molding
Implementation Method 2
subjecting the resulting plastic in the form of a sheet to vacuum forming, air-pressure forming, or vacuum air-pressure forming
Implementation Method 3
subjecting the resulting plastic in the form of a sheet to vacuum forming, air-pressure forming, or vacuum air-pressure forming
Implementation Method 4
a difference between a maximum value and a minimum value of retardation of the sheet is 3000 nm or less
Data Source
AI summary
The present invention provides a thin sheet with suppressed strain. The sheet according to the present invention has a thickness from 0.1 to 5 mm and is formed of a plastic that contains at least one resin selected from polyamide resins, polycarbonate resins, cellulose acrylate resins, and acrylic resins. A difference between a maximum value and a minimum value of retardation of the sheet is 3000 nm or less. The sheet according to the present invention can be obtained, for example, by subjecting a plastic containing at least one resin selected from polyamide resins, polycarbonate resins, cellulose acylate resins, and acrylic resins to extrusion molding to obtain a plastic in the form of a sheet, and subjecting the resulting plastic in the form of a sheet to vacuum forming, air-pressure forming, or vacuum air-pressure forming.