3D Molding Sheet Scratch Resistance via Particle Size Control
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Solution Overview
Problem
Resin molded articles for three-dimensional molding face challenges in achieving excellent scratch resistance and moldability while minimizing interference fringes, particularly when using inorganic particles in the surface protective layer, which can lead to cracks and design impairments.
Innovation Solution
A sheet for three-dimensional molding with a surface protective layer formed from a cured resin composition containing ionizing radiation curable resin and inorganic particles with an average particle size of 100 nm or more, where the inorganic particles are 40% by mass or more, and the particle size ranges from 100 to 500 nm, ensuring saturated crosslinking density and improved adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If inorganic particles with large particle size are blended in the surface protective layer, then scratch resistance is improved, but cracks are easily generated during molding
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size of inorganic particles to be 0.1 μm or more but less than 1 μm, and setting the content to 10-60 mass%. This optimization of physical parameters allows the surface protective layer to achieve excellent scratch resistance while preventing crack generation during molding, resolving the contradiction between strength and reliability.
Solution Approach 2:
The patent uses composite materials by combining ionizing radiation curable resin with specifically sized inorganic particles (silica, alumina, or zirconia) to create a surface protective layer that exhibits both high scratch resistance and molding reliability. The composite structure allows the inorganic particles to provide hardness and scratch resistance while the resin matrix maintains flexibility and prevents cracking.
2Strength
If inorganic particles are blended in the surface protective layer, then scratch resistance is improved, but interference fringes occur on the surface
Solution Approach 1:
The patent eliminates interference fringes by optimizing the particle size parameter to be 0.1 μm or more but less than 1 μm. This specific size range prevents light diffraction and interference effects that cause rainbow-colored unevenness, while still providing sufficient scratch resistance. The particle size is carefully controlled to be below the wavelength of visible light to avoid optical interference.
3Ease of manufacture
If the surface protective layer is uncured in the state of sheet for three-dimensional molding, then moldability is improved, but the process becomes complicated
Solution Approach 1:
The patent applies preliminary action by pre-blending ionizing radiation curable resin with inorganic particles in the surface protective layer before molding. This preliminary preparation ensures that the material is ready for curing after molding, eliminating the need for post-molding curing processes and simplifying the overall manufacturing process while maintaining excellent moldability.
Solution Approach 2:
The patent replaces traditional thermal curing or chemical curing methods with ionizing radiation curing (electron beam or ultraviolet irradiation). This substitution allows for rapid, on-demand curing after molding without requiring complex heating systems or chemical catalysts, thereby simplifying the manufacturing process while maintaining ease of manufacture.
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 provides excellent scratch resistance and moldability while effectively reducing interference fringes, enhancing the quality and design integrity of resin molded articles.
Implementation Method 1
the surface protective layer is formed of a cured product of a resin composition containing an ionizing radiation curable resin and inorganic particles... wherein the curing of the resin composition uses an amount of irradiation with ionizing radiation with which the crosslinking density of the surface protective layer is saturated
Data Source
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Figure 3
AI summary
The present invention provides a sheet for three-dimensional molding, said sheet having excellent scratch resistance and moldability and effectively suppressing interference fringes. Provided is a sheet for three-dimensional molding, said sheet having at least a surface protection layer laminated upon a substrate, wherein the surface protection layer is formed from a cured product of a resin composition that includes an ionizing radiation-curable resin and inorganic particles having an average particle size of 100 nm or more, and the content of the inorganic particles in the surface protection layer is 40 mass% or more.