Adhesive Patch Edge Geometry for Cold-Flow Prevention
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Solution Overview
Problem
Existing patches with soft or thick pressure-sensitive adhesive layers often experience the cold-flow phenomenon, leading to protrusion or flow-out during storage, which results in adhesion to packaging and sticky hands, and existing solutions like the dry edge technique are not fully satisfactory as they may still allow protrusion or flow-out from the backing edge and limit backing material selection.
Innovation Solution
Regulating the pressure-sensitive adhesive layer to have a specific sectional shape at the edge, with at least part of the edge located on the center side of the patch relative to the backing or release liner, and ensuring the edge is not covered by either, thereby inhibiting protrusion or flow-out and facilitating easy liner removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pressure-sensitive adhesive layer is made soft or thick to reduce physical stimulus and enable soft wear feeling, then the comfort and adhesion performance are improved, but the adhesive layer protrudes or flows out during storage due to cold-flow phenomenon
Solution Approach 1:
The patent applies different structural characteristics to different regions of the adhesive layer. The edge portion is designed with a specific sectional shape that differs from the central portion, creating localized structural optimization to prevent protrusion and flow-out at the edges while maintaining the soft and thick characteristics needed for comfort and adhesion in the central area.
Solution Approach 2:
The patent addresses the cold-flow problem by introducing a new dimensional aspect - the sectional shape at the edge portion. By controlling the geometry in the thickness dimension (creating a specific sectional shape rather than a simple flat edge), the invention prevents protrusion without compromising the overall softness and thickness of the adhesive layer.
2Object-generated harmful factors
If the release liner is projected from the edges to prevent adhesive protrusion (dry edge technique), then adhesive flow-out is reduced, but the adhesive may still protrude from the backing edge and user cannot easily pinch the release liner
Solution Approach 1:
The patent applies the dry edge technique selectively - the release liner is projected only at the edge portion where it is needed to prevent adhesive flow-out, while the central area maintains normal alignment. This localized application prevents adhesive protrusion from the backing edge while preserving the ability of users to easily pinch and remove the release liner from the edges.
3Stability of the object's composition
If the edge of the backing covers the edge of the pressure-sensitive adhesive layer, then adhesive protrusion is prevented, but the backing material selection and shape design freedom are limited
Solution Approach 1:
The patent applies different configurations to different regions: at the edge portion, the release liner is projected to prevent adhesive flow-out, while the central area allows for flexible backing material selection and shape design. This localized approach maintains adhesive position stability at critical edges while preserving design freedom for the majority of the patch area.
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 patch effectively prevents adhesive layer protrusion or flow-out during storage, allowing easy removal from packaging and reducing sticky hands, while enabling easy peeling of the release liner without excessive stickiness, thus providing a smoothly usable patch.
Implementation Method 1
pressure-sensitive adhesive layer
Implementation Method 2
soft pressure-sensitive adhesive layers obtained by incorporating an organic liquid ingredient into pressure-sensitive adhesive layers
Implementation Method 3
the pressure-sensitive adhesive layer protrudes from an edge of the patch or flows out during patch storage due to the so-called cold-flow phenomenon
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
The invention relates to a patch including a backing, a pressure-sensitive adhesive layer, and a release liner, the patch at an edge part thereof having such a sectional shape that, when a perpendicular segment is drawn from an edge of the backing at the edge part of the patch to the release liner, at least a part of an edge of the pressure-sensitive adhesive layer at the edge part of the patch is located on the center side of the patch with respect to the segment, and the edge of the pressure-sensitive adhesive layer being exposed. According to the invention, a patch and an adhesive preparation in each of which the pressure-sensitive adhesive is less apt to protrude or flow out from the edges thereof can be provided.