High Flow hSBS Block Copolymers for Low Temp Adhesives
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Solution Overview
Problem
Current styrenic block copolymers with high melt flow rates often compromise on mechanical properties, making them unsuitable for applications requiring both high strength and low viscosity, especially at low spray temperatures and in textile applications.
Innovation Solution
A laminating adhesive comprising a blend of selectively hydrogenated styrene-diene-styrene or controlled distribution styrene-diene/styrene-styrene block copolymers with a melt flow rate greater than 100 g/10 min, a linear true peak molecular weight of 45,000 to 65,000, a polystyrene content of 18 to 45%, a vinyl content of 65 to 80%, and a coupling efficiency of 60 to 97%, combined with a tackifying resin, to achieve high strength and low viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If styrenic block copolymers use high diblock content (>60 wt.%) to achieve high melt flow rate, then melt flow rate is improved, but mechanical properties deteriorate
Solution Approach 1:
The patent changes the molecular weight parameter of the block copolymer to a specific range (40,000-70,000) and adjusts the polystyrene content (13-25%) and vinyl content (60-85%) to achieve high melt flow rate (81 g/10 min) while maintaining good mechanical properties, resolving the contradiction between productivity and strength
Solution Approach 2:
The patent creates a composite structure by coupling block copolymers with specific architectural design (diblock content 20-40 wt.%) to achieve a material that simultaneously provides high melt flow rate and high elasticity, overcoming the limitation of using high diblock content alone
2Strength
If traditional hSBS block copolymers are used to ensure good mechanical properties, then strength is improved, but viscosity increases making them unsuitable for low spray temperature applications
Solution Approach 1:
The patent adjusts key parameters including linear true peak molecular weight (45,000-65,000), polystyrene content (18-45%), and vinyl content (65-80%) to achieve a balance where the adhesive maintains high strength while having low enough viscosity for spray application at reduced temperatures
Solution Approach 2:
The patent creates local quality differentiation through the block copolymer structure with specific diblock content (20-40 wt.%) and coupling efficiency (60-97%), where different regions of the polymer provide different functions - the hard segments provide strength while the soft segments provide flowability at lower temperatures
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 adhesive exhibits superior adhesive strength and elasticity, enabling its use in textile applications and other markets that require high performance at low viscosity and low spray temperatures, such as fiberglass reinforcement and low VOC coatings.
Implementation Method 1
selectively hydrogenated styrene-butadiene-styrene (hSBS, also known as SEBS) or selectively hydrogenated controlled distribution styrene-butadiene/styrene-styrene (hS-B/S-S, also known as styrene-ethylene butadiene/styrene-styrene (S-EB/S-S)) block copolymers
Data Source
Figure 1~2
AI summary
The invention relates to unique applications for the 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 under 2.16 kg mass according to ASTM D1238. These block copolymers are novel and have the highest melt flow rate of any styrenic block copolymer also possessing high strength and elasticity. It has applications that prior to the present invention were not normally possible due to the normal low melt flow rate of styrenic block copolymers.