Epoxy-Functionalized Copolymers for Adhesive Squeezing Control
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Solution Overview
Problem
Current adhesive systems, particularly reactive adhesive tapes, face challenges in achieving high bond strength while minimizing squeezing during activation and ensuring good flow behavior under pressing conditions, with limited options for reactive resins that balance these requirements effectively.
Innovation Solution
Epoxy-functionalized (co)polymers with a specific molecular weight range (5,000 g/mol to 200,000 g/mol) are developed, which exhibit excellent viscoelastic behavior, reducing squeezing and enhancing bonding strength through controlled molecular weight build-up during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low molecular weight reactive resins are used, then reactivity and curing speed are improved, but squeezing out increases due to plasticizing effect
Solution Approach 1:
The patent changes the molecular weight parameter of the reactive resin from low (conventional) to medium-high (invention: 5,000-200,000 g/mol). This parameter change eliminates the plasticizing effect that causes squeezing out, while maintaining adequate reactivity through the epoxy-functional groups. The molecular weight is optimized to balance flow behavior during application with resistance to squeezing during curing.
Solution Approach 2:
The patent creates a composite adhesive system combining the epoxy-functionalized (co)polymer (main component: 70-95 wt%) with low molecular weight epoxy resin (secondary component: 5-30 wt%). This composite structure allows the polymer matrix to provide structural integrity and resistance to squeezing, while the low molecular weight resin provides reactivity and curing capability. The synergistic combination resolves the contradiction between reactivity and squeezing resistance.
2Object-generated harmful factors
If high molecular weight polymers are used, then resistance to squeezing out is improved, but flow behavior under pressing conditions deteriorates
Solution Approach 1:
The patent optimizes the molecular weight parameter to a specific range (5,000-200,000 g/mol) that balances two opposing requirements: high enough to resist squeezing out, but low enough to maintain adequate flow behavior during hot pressing. This intermediate molecular weight range achieves both objectives simultaneously, unlike conventional low or high molecular weight resins.
Solution Approach 2:
The patent utilizes the temperature-dependent viscoelastic behavior of the epoxy-functionalized (co)polymer. During hot pressing, the polymer exhibits increased flowability due to thermal softening, enabling good wetting and contact. During curing, the polymer maintains structural integrity and resistance to squeezing. This dynamic response to temperature changes resolves the contradiction between flow behavior and squeezing resistance.
3Strength
If reactive adhesive systems are activated, then bond strength is improved, but squeezing out occurs during activation
Solution Approach 1:
The composite structure of epoxy-functionalized (co)polymer with low molecular weight epoxy resin provides differential behavior during activation: the polymer matrix maintains dimensional stability and resists squeezing out, while the low molecular weight resin provides the reactive epoxy groups that cure to achieve high bond strength. The hardener system (5-30 wt%) facilitates rapid curing without excessive flow.
Solution Approach 2:
The patent incorporates the epoxy-functionalized (co)polymer as a pre-formed matrix that provides structural cushioning before activation. This matrix prevents squeezing out during the subsequent curing process, while allowing the embedded low molecular weight epoxy resin and hardener to react and develop bond strength. The polymer matrix acts as a cushion that contains the curing reaction without allowing material ejection.
4Area of stationary object
If adhesive systems require good flow behavior onto substrates, then contact surface is improved, but squeezing out increases under pressing conditions
Solution Approach 1:
The patent exploits the dynamic viscoelastic properties of the epoxy-functionalized (co)polymer that change with temperature and stress conditions. During application and pressing, the polymer exhibits flow behavior that enables good substrate wetting and contact surface formation. During curing, the polymer transitions to a more rigid state that resists squeezing out. This dynamic property transition resolves the contradiction between flow behavior and squeezing resistance.
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
These polymers achieve a balance between flowability and reduced squeezing, leading to high bond strengths and resilient bonding conditions, with the molecular weight dependence of glass transition temperature ensuring optimal viscoelastic properties during the bonding process.
Implementation Method 1
a reaction that leads to a molecular weight increase and / or cross-linking of the polymer or at least one component of the preparation
Implementation Method 2
Radiation (in particular UV radiation) can take part as an additional stimulus in a reaction that leads to a molecular weight increase and / or cross-linking
Implementation Method 3
exhibit excellent viscoelastic behavior, reducing squeezing and enhancing bonding strength through controlled molecular weight build-up during curing
Implementation Method 4
the molecular weight dependence of glass transition temperature ensuring optimal viscoelastic properties during the bonding process
Data Source
Figure 1a~1b
Figure 2
AI summary
The invention relates to a polymer obtainable by the radical polymerization of at least one monomer, namely one or more (meth)acrylate monomers and optionally, in addition, vinylic comonomers, wherein the polymer has a molar mass MW of at least 5,000 g/mol and at most 200,000 g/mol and at least one of the monomers is functionalized with at least one epoxy group, wherein the proportion of the epoxide-functionalized monomer(s) (a) is more than 30 wt%.