Block Copolymer Adhesive Bonding Nonpolar Substrates
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Solution Overview
Problem
Existing adhesive systems based on polyesters struggle to bond nonpolar materials like polyethylene or polypropylene due to incompatibility and require surface pretreatment, and are ineffective on contaminated surfaces, with polybutadienes also being incompatible with polyester-based systems, leading to longer curing times and processing challenges.
Innovation Solution
A composition comprising the reaction product of a block copolymer based on OH-functional polybutadiene and cyclic esters, with the inclusion of 0.0001% to 40% by weight of titanium and at least 0.1% by weight of free isocyanate groups, which forms a polyol that reacts with an excess of diisocyanate to create a low-viscosity, moisture-curing adhesive with improved processing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyester-based adhesive systems are used, then rapid curing and high formulation flexibility are achieved, but bonding to nonpolar materials like polyethylene or polypropylene fails due to poor wetting and incompatibility
Solution Approach 1:
The patent creates a composite adhesive system combining polyester polyol with polybutadiene block copolymer. The polyester component provides rapid curing through moisture reaction, while the polybutadiene component provides compatibility with nonpolar materials through its nonpolar hydrocarbon segments. This composite structure allows the adhesive to bond both polar and nonpolar substrates effectively.
Solution Approach 2:
The block copolymer structure contains distinct regions with different polarities: polar polyester blocks for bonding to polar substrates and nonpolar polybutadiene blocks for bonding to nonpolar substrates. This local quality variation within the same adhesive material enables versatile bonding capabilities across different material types.
2Adaptability or versatility
If polybutadiene is used to bond contaminated surfaces, then bonding capability improves, but compatibility with polyester-based systems deteriorates
Solution Approach 1:
The patent forms a true composite material where polybutadiene blocks are covalently bonded to polyester blocks within the same polymer chain. This molecular-level integration ensures compatibility and stability of the adhesive system while retaining the ability to bond contaminated surfaces through the nonpolar polybutadiene segments.
Solution Approach 2:
The block copolymer contains localized nonpolar polybutadiene segments that can interact with contaminated surfaces, while the polar polyester segments maintain compatibility with the adhesive system and provide curing functionality. This spatial separation of functions within the polymer structure resolves the compatibility issue.
3Adaptability or versatility
If thermoplastic polyolefins are used for bonding nonpolar materials, then compatibility improves, but curing time increases
Solution Approach 1:
The adhesive combines polyolefin-like polybutadiene blocks for nonpolar material compatibility with reactive polyester blocks that can cure rapidly through moisture reaction. The block copolymer structure allows both functionalities to coexist, achieving fast curing without sacrificing compatibility with nonpolar substrates.
Solution Approach 2:
The patent modifies the chemical structure by creating block copolymers with specific compositions and molecular weights, optimizing the balance between nonpolar character (for compatibility) and reactive content (for curing speed). This parameter optimization enables fast curing while maintaining versatility.
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 enables bonding of substrates including nonpolar materials and contaminated surfaces with rapid curing and low viscosity, maintaining stability during temperature-controlled storage, addressing the limitations of existing adhesive systems by providing reactive NCO groups and improved compatibility.
Implementation Method 1
the reaction product of a block copolymer based on OH-functional unhydrogenated polyolefin, preferably OH-functional polybutadiene, and cyclic esters in the form of a polyol having at least 1.8 OH groups and at least one isocyanate compound having at least two isocyanate groups
Implementation Method 2
The reactive end groups result in a reaction with air humidity, such that the polymer cures further
Implementation Method 3
the composition includes 0.0001% to 40% by weight of titanium
Data Source
AI summary
The present invention relates to a composition comprising the reaction product of a block copolymer based on OH-functional polyolefin which is unhydrogenated, preferably polybutadiene, and cyclic esters in the form of a polyol having at least 1.8, preferably at least two, OH groups and at least one isocyanate compound having at least two isocyanate groups, which is notable in that the composition includes at least 0.0001% to 40% by weight of titanium and has a content of free isocyanate groups of at least 0.1% by weight based on the overall composition, to a process for preparation thereof and to the use of the composition for bonding of substrates.