Reinforced Polyamide Moulding Compounds with Low Haze
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Solution Overview
Problem
The existing methods for producing glass-filled polyamide molding compounds with optimal optical and mechanical properties are hindered by the need for precise control of refractive index matching between glass and polymer, which is costly and impractical for cost-effective production, and result in compromised haze and transparency.
Innovation Solution
A polyamide molding compound comprising 50-95% of a mixture of transparent, partially aromatic polyamides and 5-50% of glass filler with a refractive index between 1.510 and 1.539, along with optional additives, to achieve low haze and high transparency while maintaining mechanical strength and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass fillers are added to increase stiffness and strength, then mechanical properties are improved, but optical properties (haze and transparency) deteriorate
Solution Approach 1:
The patent changes the refractive index parameter of the glass filler from conventional values (1.49-1.509) to a higher range (1.510-1.539) to match the refractive index of transparent polyamides more closely. This parameter change reduces light scattering at the glass-polymer interface, thereby maintaining transparency while preserving the mechanical reinforcement benefits of glass fillers.
Solution Approach 2:
The patent creates a composite material system combining transparent polyamides with specifically selected glass fillers (having refractive indices of 1.510-1.539) to achieve a synergistic effect where both mechanical strength and optical transparency are maintained. The composite leverages the high strength of glass and the transparency of polyamide while minimizing optical degradation through refractive index matching.
2Illumination intensity
If refractive index of glass is matched to polymer with high precision (deviation ≤0.002), then optical properties are maintained, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent broadens the acceptable refractive index range for glass fillers from a narrow tolerance (±0.002) to a wider range (1.510-1.539), which simplifies manufacturing by reducing the precision requirements for glass composition control, melt homogeneity, and temperature regime while still achieving good optical properties.
Solution Approach 2:
The patent employs conventional glass compositions that are easier and more cost-effective to produce, eliminating the need for expensive, highly precise glass formulations. By accepting a broader refractive index range, the patent uses more economically viable glass materials that do not require stringent production controls.
3Temperature
If aromatic polyamides with high glass transition temperature are used to improve heat resistance, then heat resistance is enhanced, but processing properties deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyamide by incorporating aromatic structural units (at least 25 mol% based on total diamines and dicarboxylic acids), which increases the glass transition temperature and heat resistance while maintaining processability through careful selection of aromatic monomers and their ratios.
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 polyamide molding compounds with excellent transparency, low haze, and enhanced mechanical properties, including high heat resistance, without the need for precise refractive index matching, thus improving processing efficiency and reducing production costs.
Implementation Method 1
match the refractive index of the glass to that of the polymer... the refractive index can be set in the range from 1.510 to 1.540 measured at a wavelength of 589 nm (nD)... the refractive index to be set for the glass should not deviate from that of the polymer by more than 0.002
Data Source
AI summary
The present invention relates to a polyamide molding compound containing or consisting of the following components: (A) 50 to 95 wt.% of a mixture consisting of the specific polyamides (A1) and (A2), (B) 5 to 50 wt.% of at least one glass filler having a refractive index in the range of 1.510 to 1.539; (C) 0 to 10 wt.% of at least one additive; wherein the weight percentages of components (A) to (C) supplement each other to 100 wt.%; wherein the content of (A1) in the mixture (A) is > 50 wt% if the ratio Δ2/Δ1 is > 1 and the content of (A2) in the mixture (A) is > 50 wt% if the ratio Δ2/Δ1 ≤ 1, wherein Δ1 = n (A1) - n(B) and Δ2 = n(B) - n(A2); wherein the transparent polyamides (A1) and (A2) have a transparency of at least 90% and a haze of at most 3%; and wherein the mixture (A) has a transparency of at least 88% and a haze of at most 5%.Furthermore, the present invention relates to molded bodies made from these polyamide molding compounds.