Molding Composition Scratch Resistance Gloss Stability
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Solution Overview
Problem
Current polymer compositions for soft touch materials lack improved tactile characteristics, low gloss, mar resistance, scratch resistance, low temperature ductility, and dimension stability, particularly in automotive interiors where durability and frequent contact are concerns.
Innovation Solution
A molding composition comprising 15-80 wt.% hydrogenated styrenic block copolymers, 10-60 wt.% high-flow polypropylene, and 5-25 wt.% thermoplastic vulcanizate with a cured elastomeric phase dispersed in a thermoplastic matrix, which provides enhanced scratch resistance and reduced gloss change after aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer compositions are used for soft touch materials, then the material provides basic tactile characteristics, but the material lacks improved scratch resistance and exhibits high gloss increase after aging
Solution Approach 1:
The patent employs a composite material system consisting of hydrogenated styrenic block copolymer, polypropylene, and thermoplastic vulcanizate. This multi-component composition creates a heterogeneous structure where each component contributes specific properties: the HSB copolymer provides scratch resistance and soft touch feel, the polypropylene offers structural stability and dimensional control, and the TPV phase enhances durability. The composite nature allows simultaneous achievement of scratch resistance and gloss stability that single-component materials cannot provide.
Solution Approach 2:
The patent specifies precise parameter ranges for each component to optimize performance: HSB copolymer melt index of 12-300 g/10min, polypropylene melt flow index greater than 300 g/10min, TPV Shore A hardness of 60-90, and specific composition ratios (15-80 wt% HSB, 10-60 wt% polypropylene, 5-25 wt% TPV). These parameter controls ensure the material achieves the desired balance between scratch resistance, soft touch characteristics, and gloss retention after aging.
2Ease of operation
If the material is designed for soft touch feel, then tactile characteristics are improved, but durability against frequent touching and scratching deteriorates
Solution Approach 1:
The patent creates local quality differentiation through the thermoplastic vulcanizate structure, where cured elastomeric phases are dispersed within the thermoplastic matrix. The HSB copolymer domains provide localized soft touch and flexibility, while the cross-linked TPV phases provide localized durability and scratch resistance. This spatial distribution of different properties within the material allows simultaneous achievement of soft touch feel and scratching durability.
3Ease of manufacture
If high polypropylene content is used to improve flow and molding, then manufacturing ease is improved, but tactile characteristics and soft touch feel worsen
Solution Approach 1:
The patent specifies precise parameter ranges to balance manufacturing ease with tactile properties: polypropylene melt flow index greater than 300 g/10min ensures good flow and molding, while the overall composition (10-60 wt% polypropylene combined with 15-80 wt% HSB copolymer and 5-25 wt% TPV) maintains soft touch characteristics. The high melt flow index of polypropylene compensates for its potential to reduce softness, allowing easier molding while preserving tactile quality.
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 composition achieves improved scratch resistance and reduced gloss retention after heat and UV-aging, maintaining a soft touch feel while withstanding frequent contact and scratches, making it suitable for automotive interior applications.
Implementation Method 1
hydrogenated styrenic block copolymers having a general formula: S-E-S, (S-E1)n, (S-E1)nS, (S-E1)nX
Implementation Method 2
a thermoplastic vulcanizate, in which a cured elastomeric phase is dispersed in a thermoplastic material in a matrix
Implementation Method 3
forming the injection molded article from the molding composition by injection molding
Data Source
AI summary
Injection molded articles having improved scratch resistance and reduced gloss change after heat and UV aging are disclosed. The article is formed from a molding composition having a melt flow index of 50-350 g/10 (230°C, 2.16 kg) as measured by ASTM D1238-04, the composition consisting essentially of: a) 15-80 wt. % of a hydrogenated styrenic block copolymer having a melt index of at least 12 grams/10 minutes according to ASTM D1238 at 230°C and 2.16 kg weight; b) 10-60 wt. % of a polypropylene having a melt flow index greater than 300g/10 min, measured under 230°C/2.16 kg according to ISO 1133-1; and c) 5-25 wt. % of a thermoplastic vulcanizate having a Shore A hardness from 60-90 (15 sec, 23°C) as measured according to ISO 868. The article has a gloss increase after 10 days of aging at 120°C of less than 100%, relative to an initial gloss, as determined by PSA D47 1850.