Hydrogenated Block Copolymer Gel Compositions for High-Temperature Stability
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Solution Overview
Problem
Existing gel compositions, such as elastosols, UV curable gels, and chemically curable gels, often lack the necessary properties for high-temperature applications and processability, particularly in automotive paint baking ovens and other demanding scenarios, where they may become too soft or liquid, and current methods for preparing these gels are inefficient.
Innovation Solution
A method involving the use of selectively hydrogenated block copolymers and ester compounds to create solid, rubbery gel compositions that can be processed at ambient temperatures, incorporating specific molecular weight ranges, vinyl content, and crosslinking agents to achieve improved thermal stability and processability, allowing for the formation of coherent, elastic compositions suitable for sealants, caulks, and various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional gel compositions are used, then they can be prepared and handled easily, but they become too soft or liquid at high temperatures, losing their structural integrity
Solution Approach 1:
The patent changes the chemical parameters of the gel composition by incorporating specific block copolymers with controlled hydrogenation levels (0-10% of arene double bonds reduced, at least 90% of conjugated diene double bonds reduced) and specific molecular weight distributions. This parameter optimization allows the gel to maintain structural integrity at high temperatures while remaining processable at ambient temperatures.
Solution Approach 2:
The patent creates a composite gel system combining block copolymer networks with ester compounds (70-90 wt% esters, 10-30 wt% polymer). This composite structure integrates the thermal stability of hydrogenated block copolymers with the processability of ester compounds, resolving the contradiction between high-temperature stability and ambient-temperature handleability.
2Strength
If high molecular weight block copolymers are used to improve gel strength, then the gel becomes too viscous and difficult to process at ambient temperatures
Solution Approach 1:
The patent optimizes the molecular weight parameters of the block copolymer components, specifying A blocks with Mn 25,000-35,000, B blocks with Mn 100,000-150,000, and C blocks with Mn 50,000-75,000. This controlled molecular weight distribution provides sufficient gel strength while maintaining adequate fluidity for processing at ambient temperatures.
Solution Approach 2:
The patent applies different molecular weight characteristics to different blocks within the copolymer structure. The A blocks provide strength with moderate molecular weight, while the B and C blocks with higher molecular weights provide elasticity and processability. This local differentiation of molecular weight properties resolves the contradiction between strength and processability.
3Ease of manufacture
If conventional elastosol preparation methods are used, then the preparation process is simple, but the resulting gels lack the necessary properties for high-temperature applications such as sealants in automotive paint baking ovens
Solution Approach 1:
The patent performs preliminary selective hydrogenation of the block copolymer before gel formation, reducing 90% or more of the conjugated diene double bonds while leaving 0-10% of arene double bonds intact. This preliminary modification ensures the gel will maintain its properties at high temperatures without requiring complex post-processing or formulation adjustments.
Solution Approach 2:
The patent segments the hydrogenation process into selective stages, first hydrogenating the conjugated diene blocks extensively (≥90% reduction) while preserving the arene blocks (0-10% reduction). This segmented approach creates a copolymer with differentiated thermal properties that ensure high-temperature reliability while maintaining ease of manufacture.
4Stability of the object's composition
If UV curable and chemically cured gels are used to improve crosslinking and stability, then the gel structure improves, but the preparation process becomes more complex and requires additional curing steps
Solution Approach 1:
The patent enables the gel system to self-crosslink through the controlled hydrogenation of the block copolymer, which creates inherent crosslinking sites that react during gel formation without requiring external UV irradiation or additional chemical curing agents. This self-service mechanism achieves stable crosslinked structures while maintaining simple preparation 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
The method results in gel compositions that can be handled as pastes at ambient temperatures, fusing into coherent, elastic materials at high temperatures, offering improved utility as heat fusible sealants and coatings, and simplifying the preparation of solid, rubbery gels and UV cured gels by enabling incorporation of expandable microspheres and chemical blowing agents at lower temperatures.
Implementation Method 1
mixing 5 to 50 parts by weight of a block copolymer and 95 to 50 parts by weight of a benzoate ester having a melting point between about 70° C. and about 170° C. and mixing at a temperature above the melting point of the ester
Implementation Method 2
subsequent to hydrogenation about 0-10 % of the arene double bonds have been reduced, and at least about 90% of the conjugated diene double bonds have been reduced
Data Source
AI summary
Disclosed are four gel compositions that have improved properties over the prior art. These gels include elastosols, solid rubbery gels, UV cured gels and chemically cured gels. The gels are formed from selectively hydrogenated styrene/diene block copolymers, unhydrogenated styrene/diene block copolymers, and selectively hydrogenated styrene/diene block copolymers that have been maleated.