Multilayer Pressure Sensitive Adhesive for Polyolefin Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pressure sensitive adhesives (PSAs) with acrylic polymers face challenges in achieving good adhesion to polyolefin substrates while minimizing the use of tackifier, as existing solutions often require higher tackifier amounts and may not effectively bond due to surface energy mismatches between polar acrylic polymers and non-polar polyolefins.
Innovation Solution
A pressure sensitive adhesive article comprising a tackifier-free acrylic polymer layer with a weight-average molecular weight of 50,000 or higher, in contact with a tackifier-containing hydrocarbon polymer layer, both having glass transition temperatures of -10°C or lower, and a total tackifier amount of 12% or less by weight, forming a bonded article with improved adhesion and reduced tackifier migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tackifier-free acrylic polymer layer is used, then adhesion to polyolefin substrates is improved, but bonding strength deteriorates
Solution Approach 1:
The adhesive article is divided into multiple layers: a tackifier-free acrylic polymer layer (Lb) in contact with the substrate, and a tackifier-containing hydrocarbon polymer layer (Lc) providing bonding strength. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between adhesion and bonding strength.
Solution Approach 2:
Different layers are assigned different material properties: the acrylic polymer layer has low surface energy for polyolefin adhesion, while the hydrocarbon polymer layer has high tackifier content for bonding strength. This local differentiation of material qualities allows simultaneous achievement of both adhesion and bonding strength.
2Reliability
If tackifier amount is reduced, then adhesion to polyolefin substrates is improved, but bonding strength deteriorates
Solution Approach 1:
The adhesive system is segmented into two functional layers: Layer Lb contains minimal or no tackifier for polyolefin adhesion, while Layer Lc contains the tackifier for providing bonding strength. This segmentation resolves the contradiction by spatially separating the conflicting requirements.
Solution Approach 2:
The adhesive article uses a composite structure combining acrylic polymer (for adhesion) and hydrocarbon polymer with tackifier (for bonding strength). This composite material approach allows the system to simultaneously achieve both adhesion to polyolefin and adequate bonding strength.
3Strength
If tackifier amount is increased, then bonding strength is improved, but adhesion to polyolefin substrates deteriorates
Solution Approach 1:
The adhesive is segmented into Layer Lb (tackifier-free acrylic polymer for polyolefin adhesion) and Layer Lc (tackifier-containing hydrocarbon polymer for bonding strength). This segmentation allows high tackifier content in Layer Lc without compromising polyolefin adhesion in Layer Lb.
Solution Approach 2:
Different layers have different tackifier concentrations: Layer Lb has zero or low tackifier for optimal polyolefin adhesion, while Layer Lc has high tackifier for bonding strength. This local quality differentiation resolves the contradiction between bonding strength and adhesion.
4Reliability
If acrylic polymer with high molecular weight is used, then adhesion to polyolefin substrates is improved, but processing difficulty increases
Solution Approach 1:
The high molecular weight acrylic polymer is processed as a latex dispersion (aqueous emulsion) in Layer Lb, which improves processability while maintaining the high molecular weight for adhesion performance. The latex form allows easier application and drying compared to pure high molecular weight polymer.
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 provides enhanced adhesion to polyolefin surfaces and other substrates, with improved resistance to shear and minimal tackifier migration, while maintaining a low tackifier content, thus addressing the limitations of existing PSA technologies.
Implementation Method 1
A pressure sensitive adhesive article comprising (a) a substrate (Sa), (b) in contact with said substrate (Sa), a layer (Lb) of a tackifier-free composition (Cb) that comprises one or more acrylic polymer (POLb)
Implementation Method 2
a layer (Lc) of a tackifier-containing composition (Cc) that comprises one or more tackifier and one or more hydrocarbon polymer (POLc) having Tg determined according to the method described herein of -10°C
Data Source
Figure 1~2
AI summary
Provided is a pressure sensitive adhesive article comprising (a) a substrate (Sa), (b) in contact with said substrate (Sa), a layer (Lb) of a tackifier-free composition (Cb) that comprises one or more acrylic polymer (POLb) having Tg of -10°C or lower, and (c) in contact with said layer (Lb), a layer (Lc) of a tackifier-containing composition (Cc) that comprises one or more tackifier and one or more hydrocarbon polymer (POLc) having Tg of 10°C. Also provided is a bonded article made by a process comprising contacting a substrate (Sd) with such a pressure sensitive adhesive article, wherein said substrate (Sd) is in contact with said layer (Lc).