Pressure-Sensitive Adhesive Sheet With Urethane Anchor Layer
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Solution Overview
Problem
Pressure-sensitive adhesive (PSA) sheets with acrylic PSA layers formed from water-dispersed compositions face challenges in achieving high adhesive strength and ease of rework simultaneously, as greater adhesive strength often leads to cohesive or anchor fractures, and conventional methods like isocyanate-based crosslinking can result in inconsistent quality due to reactivity issues.
Innovation Solution
A PSA sheet with a urethane-based anchor layer and a tackifier resin, where the PSA layer comprises an acrylic polymer with a high percentage of alkyl (meth)acrylate monomers and a tackifier resin, ensuring anchoring strength of 15 N/20mm or greater and peel strength of 6 N/20mm or greater, allowing for excellent anti-residue properties and high initial wettability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive strength is increased, then bonding performance improves, but ease of rework deteriorates due to cohesive or anchor fractures
Solution Approach 1:
The invention divides the adhesive system into two distinct functional layers: a PSA layer for providing adhesive strength and bonding performance, and an anchor layer for enabling ease of rework and preventing residue. This segmentation allows each layer to be optimized independently - the PSA layer can be formulated for strong bonding while the anchor layer provides controlled release properties, thus resolving the contradiction between adhesive strength and ease of rework.
Solution Approach 2:
The invention applies local quality by giving different regions of the adhesive composition different properties. The PSA layer has high adhesive strength for bonding, while the anchor layer has specific compositional characteristics (including solvents and adhesion promoters) that enable easy removal without residue. This spatial differentiation of properties allows simultaneous achievement of strong bonding and easy rework.
2Object-affected harmful factors
If water-dispersed PSA composition is used, then environmental health improves, but anchoring to plastic film deteriorates
Solution Approach 1:
The invention introduces an anchor layer as an intermediary between the water-dispersed PSA composition and the plastic film substrate. This anchor layer contains solvents and adhesion promoters that facilitate strong anchoring to the plastic film, compensating for the inherently weaker anchoring properties of water-dispersed compositions. The intermediary layer enables water-based environmentally friendly formulations to achieve sufficient anchoring strength.
Solution Approach 2:
The invention uses composite materials by combining the water-dispersed PSA composition with an anchor layer containing solvents and adhesion promoters. This composite structure leverages the environmental benefits of water-based formulations while the anchor layer provides the necessary anchoring strength to plastic film, thus resolving the contradiction between environmental health and anchoring performance.
3Strength
If isocyanate-based crosslinking agent is used, then anchoring improves, but manufacturing consistency deteriorates due to reactivity with water
Solution Approach 1:
The invention changes the chemical parameters of the anchor layer formulation by including solvents and adhesion promoters with controlled reactivity characteristics. This parameter adjustment allows achieving strong anchoring while maintaining manufacturing consistency, avoiding the quality issues associated with highly reactive isocyanate-based crosslinking agents that react unpredictably with water in the emulsion.
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 PSA sheet achieves a balance of high adhesive strength and ease of rework, preventing residue and ensuring strong anchoring without cohesive or anchor fractures, with improved initial wettability for quick bonding to adherends.
Implementation Method 1
a PSA sheet that combines adhesive strength and ease of rework at a high level
Implementation Method 2
an anchor layer placed between the PSA layer and the carrier film
Implementation Method 3
a urethane-based anchor layer
Implementation Method 4
The PSA layer comprises an acrylic polymer as the base polymer
Implementation Method 5
high initial wettability for quick bonding to adherends
Data Source
Figure 1~3
AI summary
[Problem] To provide a PSA sheet that combines adhesive strength and ease of rework at a high level. [Solution] Provided is a PSA sheet that comprises a PSA layer formed from a water-dispersed PSA composition, carrier film supporting the PSA layer, and an anchor layer placed between the PSA layer and the carrier film. The carrier film includes plastic film forming at least its anchor layer side. The PSA layer comprises, as its base polymer, an acrylic polymer that is a polymer of monomers including more than 50 % (by weight) C6-10 alkyl (meth)acrylate. The PSA sheet shows a peel strength to stainless steel of 6 N/20mm or greater and the PSA layer shows an anchoring strength of 15 N/20mm or greater.