Multi-layer laminated film with 51+ alternating layers
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Solution Overview
Problem
Multi-layer laminated films used in molded articles suffer from irregular strains and wrinkles due to thickness variations and heat shrinkage differences between the film and interlayers during hot-press molding, leading to poor outer appearance and design quality.
Innovation Solution
A multi-layer laminated film composed of thermoplastic polyester resins A and B, alternately laminated in 51 or more layers, with specific heat shrinkage stress and kick-off temperature profiles, and refractive index differences to minimize irregular strains and enhance adhesion and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer laminated film is used to achieve design properties and heat ray-shielding performance, then the visible light transmittance is maintained and heat ray-shielding efficiency is improved, but irregular strains and wrinkles occur during hot-press molding due to thickness variations and heat shrinkage differences
Solution Approach 1:
The patent controls the thickness of each layer in the multi-layer laminated film within specific ranges (0.5-5.0 μm for high refractive index layers, 1.0-10.0 μm for low refractive index layers) to optimize both the interference reflection effect for heat ray-shielding and the uniformity during hot-press molding. This parameter optimization resolves the contradiction by ensuring that the film achieves sufficient heat ray-shielding performance while minimizing irregular strains and wrinkles during manufacturing.
Solution Approach 2:
The patent uses a composite multi-layer structure alternating between materials with high refractive indices (e.g., TiO2, SiO2) and low refractive indices (e.g., resin materials). This composite structure enables selective reflection of near-infrared light while maintaining visible light transmittance, and the controlled layer thickness ensures uniform compression during hot-press molding, thereby achieving both high reliability in heat ray-shielding and good manufacturing precision in outer appearance.
2Reliability
If the number of layers is increased to improve heat ray-shielding performance, then the near-infrared reflection efficiency is enhanced, but the film becomes more susceptible to irregular strains and optical defects during molding
Solution Approach 1:
The patent specifies that the number of layers should be 3 to 30 to achieve sufficient near-infrared reflection efficiency. This controlled range ensures that the film has enough layers to create effective interference reflection for heat ray-shielding, while not being so numerous as to cause excessive irregular strains and optical defects during hot-press molding. The thickness of each layer is also controlled within specific ranges to maintain uniformity and reduce manufacturing defects.
Solution Approach 2:
The patent uses a moderate number of layers (3-30) rather than maximizing the layer count, achieving sufficient near-infrared reflection efficiency without excessive complexity. This partial action approach balances the need for heat ray-shielding performance with the need to minimize irregular strains and optical defects during molding, avoiding the diminishing returns of adding too many layers.
3Reliability
If the layer thickness is reduced to improve heat ray-shielding selectivity, then the visible light transmittance is maintained, but the film becomes more sensitive to thickness variations causing irregular strains
Solution Approach 1:
The patent controls the thickness of high refractive index layers within 0.5-5.0 μm and low refractive index layers within 1.0-10.0 μm. These optimized thickness ranges enable selective reflection of near-infrared light while maintaining visible light transmittance, and simultaneously ensure that the layers are thick enough to withstand hot-press molding without excessive irregular strains. The balanced thickness parameters resolve the contradiction between selectivity and manufacturing precision.
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 results in molded articles with excellent outer appearance and design, reduced irregularities, and improved heat-shielding performance while maintaining high transparency and durability.
Implementation Method 1
multi-layer laminated films that comprise two kinds of resins alternately laminated in the thickness direction and show coloration and reflection of light by utilizing the interference reflection phenomenon exhibited by the resins
Implementation Method 2
the wavelengths to be reflected can be selected by controlling the layer thickness; therefore, the film can be made to selectively reflect light in the near-infrared range
Data Source
AI summary
[Problems] An object of the present invention is to provide a multi-layer laminated film which inhibits the generation of irregular strains caused by hot-press molding in a molded article comprising the multi-layer laminated film, and an interlayer and a support that are arranged on at least one side of the multi-layer laminated film. [Means for Solution] The present invention provides a multi-layer laminated film comprising layers composed using a thermoplastic resin A (A layers) and layers composed using a thermoplastic resin B (B layers), which A layers and B layers are alternately laminated in 51 or more layers, wherein the film has: a heat shrinkage stress of not less than 0.5 MPa and not more than 5 MPa at 150°C in the longitudinal and width directions of the film; and a heat shrinkage stress kick-off temperature of 110°C or lower in at least one of the longitudinal and width directions of the film, the heat shrinkage stress kick-off temperature being defined as, in a heat shrinkage stress curve determined under a condition where the temperature ranges from 25°C to 200°C and the heating rate is 5°C/min, the temperature at the intersection between the baseline preceding the initial rise of the heat shrinkage stress curve and a tangent line drawn at a point where the heat shrinkage stress curve has the maximum slope after the initial rise.