Transparent Multilayer Body for Backlit Decorative Layer Molding
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Solution Overview
Problem
Existing methods for producing multilayer components with thermo- or pressure-sensitive decorative layers, such as those used in automotive interiors, suffer from high reject rates due to thermal burns, deformations, and mechanical damage during injection molding, leading to unsatisfactory appearance and functionality.
Innovation Solution
A multilayer body comprising a carrier layer made of a thermoplastic molding compound, specifically aromatic polycarbonate or aromatic polyester carbonate, combined with a decorative layer of materials like stone, animal hide, or textile, optimized for low melt viscosity and high light transmission and diffusivity, allowing for improved processing and reduced reject rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high temperatures and pressures are used in the IMD process, then the thermoplastic molding compound can be properly injected and bonded, but the decorative layer suffers thermal burns, deformations, and mechanical damage leading to high reject rates
Solution Approach 1:
The patent applies parameter changes by modifying the thermal and rheological properties of the polycarbonate molding compound. Specifically, it controls the melt temperature range (240-320°C) and adjusts molecular weight parameters to achieve optimal melt flow without excessive pressure, thereby preventing decorative layer damage while ensuring proper injection and bonding.
Solution Approach 2:
The patent uses composite materials by combining polycarbonate with specific additives and modifiers that enhance processability while maintaining structural integrity. The molding compound comprises a base polycarbonate resin combined with processing aids and modifiers that reduce melt viscosity and improve flow characteristics, allowing lower injection pressures that protect the decorative layer.
2Illumination intensity
If the decorative layer is made thin to allow good light transmission, then luminous efficacy is improved, but the layer becomes more susceptible to thermal and mechanical damage
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness parameters of the decorative layer within specific ranges (0.01-1.0 mm depending on material type) and adjusting the thermal parameters of the molding process. This allows sufficient light transmission for good luminous efficacy while maintaining enough structural integrity to prevent thermal burns and mechanical damage during injection molding.
3Productivity
If high injection pressure is used to ensure complete mold filling, then productivity is improved, but the decorative layer suffers mechanical damage such as cracks, chips, and bursting
Solution Approach 1:
The patent applies parameter changes by modifying the rheological parameters of the polycarbonate molding compound to achieve lower melt viscosity. This enables complete mold filling at reduced injection pressures (specifically controlling pressure to prevent decorative layer damage), thereby maintaining productivity while preventing mechanical damage such as cracks, chips, and bursting of the decorative layer.
4Illumination intensity
If the carrier layer has high light transmission for good backlighting, then illumination quality is improved, but the material requires higher processing temperatures that can damage the decorative layer
Solution Approach 1:
The patent applies parameter changes by selecting and optimizing the molecular weight parameters of the polycarbonate carrier layer to achieve a balance between light transmission and processability. By controlling the weight-average molecular weight within specific ranges and adjusting the melt flow rate, the patent achieves high light transmission for good backlighting quality while reducing the required processing temperatures to prevent decorative layer damage.
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 a diffusely translucent multilayer body with enhanced light yield and aesthetic appearance, reducing production rejects and ensuring uniform illumination, while meeting automotive industry requirements for durability and appearance.
Implementation Method 1
the multilayer body is illuminated with light from a light source arranged such that the multilayer body is illuminated with light emitted by the light source
Implementation Method 2
the base layer made of thermoplastic molding compound also exhibits sufficient light transmission in the visible wavelength range... can be used as a diffuse lighting element
Data Source
Figure 1
AI summary
The invention relates to a multi-layer body, comprising (I) a carrier layer made of a special thermoplastic polycarbonate molding compound and (II) a layer made of a material selected from the group consisting of stone products, hide products, textile fabrics containing synthetic fibers, materials of plant origin or materials containing components of plant origin, or laminates containing one or more of the aforementioned materials, wherein the layer (II) has either a specified minimum transmission or at least one recess in the shape of at least one symbol, a pattern, a hole, a line, or a sign, or the layer has punctiform recesses. The invention also relates to a lighting unit, comprising the multi-layer body and a light source, to a method for producing the multi-layer body, and to the use of the special thermoplastic polycarbonate molding compound as a carrier layer of such a multi-layer body.