High Melt Flow Hydrogenated SBS Block Copolymers
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Solution Overview
Problem
Styrenic block copolymers have limitations due to their low melt flow rates, which restrict their applications in high-performance composite materials, low viscosity coatings, and adhesives, as they typically exhibit high viscosity and poor mechanical properties, making it difficult to achieve the necessary balance between low volatile organic compounds (VOC), high solids content, and low viscosity.
Innovation Solution
Development of high melt flow rate styrenic block copolymers with a melt flow rate greater than 100 g/10 min at 230°C, characterized by a minimum linear molecular weight of 45,000 to 65,000, polystyrene content between 18 to 45 wt.%, vinyl content of 65 to 80 mole%, and coupling efficiency of 60 to 97%, allowing for enhanced strength, elasticity, and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the melt flow rate of styrenic block copolymers is increased, then the viscosity decreases and processability improves, but the mechanical properties deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight (45,000-65,000), polystyrene content (18-45 wt.%), vinyl content (65-80 mole%), and coupling efficiency (60-97%) to achieve a unique balance where high melt flow rate (>100 g/10 min) is obtained while maintaining good mechanical properties, resolving the traditional trade-off between processability and strength
Solution Approach 2:
The patent creates a composite-like structure within the block copolymer itself, combining polystyrene blocks (providing strength and elasticity) with polydiene blocks (providing flow characteristics), where the specific composition and coupling create a material that exhibits both high melt flow and retained mechanical performance
2Object-generated harmful factors
If the solids content of coatings is increased to reduce VOC, then the viscosity increases and applicability decreases
Solution Approach 1:
The patent changes the fundamental parameter of the polymer's melt flow characteristics by achieving >100 g/10 min melt flow rate, which allows coating formulations to maintain low viscosity even at high solids content, enabling VOC reduction without sacrificing ease of application through spraying or rolling
3Strength
If the molecular weight of styrenic block copolymers is increased to improve strength, then the melt flow rate decreases and processability worsens
Solution Approach 1:
The patent identifies and controls critical parameters including molecular weight (45,000-65,000), polystyrene content (18-45 wt.%), vinyl content (65-80 mole%), and coupling efficiency (60-97%) to achieve the optimal balance point where sufficient strength is obtained while maintaining high melt flow rate for good processability
4Strength
If traditional composite designs use fiberglass mat plies with reactive resins to achieve impact resistance, then the manufacturing complexity and cure time increase
Solution Approach 1:
The patent extracts the toughening function from the complex traditional system (fiberglass mats with reactive resins requiring curing) and incorporates it directly into the thermoplastic block copolymer structure itself, providing impact resistance through the polymer's inherent elastomeric properties without requiring additional reinforcement layers or curing processes
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
Enables new applications in toughened fiberglass, low VOC polymer coatings, high-performance adhesives, and film/non-woven personal hygiene products by providing improved impact resistance, elasticity, and processability while maintaining low viscosity and VOC compliance.
Implementation Method 1
subsequent to hydrogenation about 0-10% of the styrene double bonds have been hydrogenated and at least 80% of the conjugated diene double bonds have been hydrogenated
Data Source
Figure 1~2
AI summary
The invention relates to unique applications for novel high melt flow, low viscosity, selectively hydrogenated styrene-butadiene-styrene (hSBS) or selectively hydrogenated controlled distribution styrene-butadiene/styrene-styrene (hSBSS) block copolymers, wherein the melt flow rate of said block copolymer is at least 100 g/10 min at (230°C / 2.16 kg) according to ASTM D1238. These block copolymers have exceptionally high melt flow rate while also possessing high strength and elasticity. The inventive styrenic block copolymers have applications that prior to the present invention were not normally possible due to the normal low melt flow rate of styrenic block copolymers. The present invention also encompasses various fields of use such as a fiberglass hSBS or hSBSS reinforced mat, low viscosity hSBS or hSBSS coatings for industrial uses, hot melt adhesives prepared from hSBS or hSBSS blended with polyalpha-olefins, and elastic film, fiber, and nonwoven constructions using hSBS or hSBSS.