UV-Crosslinkable HMPSA Composition for High-Temperature Adhesion
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Solution Overview
Problem
Conventional hotmelt pressure sensitive adhesives (HMPSAs) lack sufficient adhesive strength at high temperatures, making them unsuitable for applications requiring stability over a wide temperature range, such as in the automotive and packaging industries.
Innovation Solution
A UV-crosslinkable HMPSA composition comprising 10-24% block copolymer with a polybutadiene block containing at least 25% 1,2-vinyl units, 43-65% tackifying resin, 10-25% liquid plasticizer, and a photoinitiator, which is applied and crosslinked to provide enhanced tack and adhesive strength up to 160°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hotmelt pressure sensitive adhesive compositions are used, then immediate tack at ambient temperature is achieved, but adhesive strength at high temperature deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the adhesive by incorporating UV-crosslinkable functional groups into the hotmelt polymer chains. This chemical modification enables the adhesive to undergo crosslinking transformation when exposed to UV radiation, fundamentally altering its molecular architecture from linear to three-dimensional network structure, thereby achieving both immediate tack and high-temperature strength
Solution Approach 2:
The patent creates a composite adhesive system by combining hotmelt polymer with UV-crosslinkable functional groups and crosslinking agents. This composite structure integrates the advantageous properties of hotmelt adhesives (immediate tack, ease of application) with the high-temperature stability provided by crosslinked polymer networks, resolving the contradiction between ambient temperature performance and high temperature strength
2Strength
If UV-crosslinkable HMPSA composition is used to improve high-temperature strength, then adhesive strength at high temperature is improved, but complexity of composition increases
Solution Approach 1:
The patent merges the UV-crosslinkable functional groups directly into the hotmelt polymer chains during synthesis, rather than using separate additives. This integration approach combines multiple functions (adhesion, high-temperature stability, and crosslinking capability) into a single polymer material, reducing composition complexity while maintaining improved high-temperature strength
Solution Approach 2:
The UV-crosslinkable functional groups within the hotmelt polymer chains enable self-crosslinking when exposed to UV radiation, eliminating the need for separate crosslinking agents or complex multi-component systems. The polymer essentially crosslinks itself through UV irradiation, simplifying the overall composition while achieving the desired high-temperature strength
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 composition achieves improved adhesion and tack at ambient temperatures, with a Shear Adhesion Failure Temperature (SAFT) of at least 160°C, ensuring secure bonding across a broad temperature range.
Implementation Method 1
UV-crosslinkable hotmelt pressure sensitive adhesive compositions are already known in the prior art as being strong at high temperature
Implementation Method 2
a polybutadiene block A2 comprising at least 25% by weight of the 1,2-vinyl unit... which is deposited (or coated) on a carrier in the melted state, and provide the latter, after cooling, with a high tack and high adhesive strength
Data Source
AI summary
A UV-crosslinkable HMPSA composition comprises 10-24% by weight of a block copolymer comprising a styrenic block and a polybutadiene block comprising at least 25% by weight of the 1,2-vinyl unit; 43-65% by weight of a tackifying resin obtained by polymerization, then complete or partial hydrogenation of a C9 fraction, having a softening point of 80-150° C.; 10-25% by weight of a petroleum-derived hydrocarbon oil; and an appropriate amount of a photoinitiator (D). A self-adhesive article comprises a carrier layer (b) coated with a self-adhesive layer (a) comprising the HMPSA composition in the crosslinked state.