Polypropylene Resin Composition for Precision Optical Molding
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Solution Overview
Problem
Precision-injection-molded bodies made from polypropylene resin compositions tend to deform after molding, which can alter their shape and compromise their precision.
Innovation Solution
A polypropylene resin composition with a propylene-based polymer copolymerized with ethylene or α-olefins, containing 3-5% monomer units by mass, and incorporating a nucleating agent such as metal salts or amide-based organic compounds, with a molecular weight distribution of 3 or less and a crystallization half-time of 20 seconds or shorter, is used to reduce deformation by controlling crystal size and rapid crystallization during injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polypropylene resin composition is used as molding material, then cost is reduced, but deformation after molding occurs
Solution Approach 1:
The patent applies parameter changes by precisely controlling the copolymerization monomer content (3-5% by mass) and molecular weight distribution (3 or less) of the polypropylene-based polymer, and by optimizing the nucleating agent content (50-3500 ppm), to achieve rapid crystallization (half-time ≤20 seconds) that prevents post-molding deformation while maintaining cost-effectiveness
Solution Approach 2:
The patent uses composite materials by combining polypropylene-based polymer with specific copolymerization monomers (ethylene or α-olefins) and nucleating agents to create a resin composition that achieves both low cost and high dimensional precision through controlled crystallization behavior
2Manufacturing precision
If rapid crystallization is achieved, then deformation is reduced, but crystal size control becomes critical
Solution Approach 1:
The patent controls crystal size through parameter changes by adjusting the copolymerization monomer content to 3-5% by mass, which modifies the polymer chain structure to promote formation of numerous small crystals rather than few large crystals, achieving rapid crystallization with half-time of 20 seconds or less
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 solution significantly reduces deformation in precision-injection-molded bodies, enhancing their mechanical strength, transparency, and stability, allowing for the production of optical members with high dimensional precision.
Implementation Method 1
The crystallization half-time at 110°C of the polypropylene resin composition is 20 seconds or shorter
Implementation Method 2
As the proportion of monomer units derived from the copolymerization monomer is 3 to 5% by mass, there is a tendency that size of crystals formed in a molded body is small
Data Source
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AI summary
Disclosed is a polypropylene resin composition which contains a polypropylene-based polymer containing, as monomer units, propylene and at least one copolymerization monomer of ethylene or α-olefins with carbon atom number of 4 or more. Proportion of the monomer units derived from the copolymerization monomer in the polypropylene-based polymer is 2 to 10% by mass based on the mass of the polypropylene-based polymer. A crystallization half-time at 110°C of the polypropylene resin composition is 20 seconds or shorter.