Heat-Activated PSA Composition for Linerless Labels
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Solution Overview
Problem
Existing heat-activated pressure-sensitive adhesives lack both good adhesive properties and blocking properties, which are essential for effective label production without a liner.
Innovation Solution
A composition comprising 20-75 dry wt% of a styrene-diene block copolymer, 0.5-20 dry wt% of a plasticizer, and 20-75 dry wt% of a tackifier, combined and coated on paper or plastic film, with specific solubility parameters and processing conditions to achieve optimal adhesive and blocking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat-activated pressure-sensitive adhesive is used for label production without a liner, then productivity is improved, but adhesive properties and blocking properties are insufficient
Solution Approach 1:
The patent uses a composite adhesive system combining a styrene-diene block copolymer (providing thermal activation and blocking resistance) with a polyester polymer (providing adhesive strength). This composite approach allows the adhesive to simultaneously achieve good adhesive properties, good blocking properties, and suitability for linerless label production, resolving the technical contradiction between productivity improvement and reliability maintenance.
2Strength
If adhesive polymer and tackifier are combined to improve adhesive properties, then adhesive strength increases, but blocking properties deteriorate
Solution Approach 1:
The patent carefully controls the ratio of adhesive polymer to tackifier within specific ranges (adhesive polymer: 5-50 wt%, tackifier: 50-45 wt%) to optimize the balance between adhesive strength and blocking resistance. By adjusting these compositional parameters, the adhesive achieves both strong bonding and resistance to blocking failures, resolving the contradiction between adhesive strength and blocking properties.
Solution Approach 2:
The patent creates a composite adhesive system where the styrene-diene block copolymer provides thermal activation and blocking resistance, while the polyester polymer provides adhesive strength. This composite approach allows simultaneous achievement of good adhesive properties and good blocking properties, resolving the technical contradiction between adhesive strength and blocking resistance.
3Ease of operation
If plasticizer is added to improve adhesive flexibility, then adhesive properties improve, but the adhesive becomes susceptible to blocking
Solution Approach 1:
The patent controls the plasticizer content within a specific range (0.5-20 wt%) to maintain adhesive flexibility while preventing excessive softening that would lead to blocking. By optimizing this parameter, the adhesive achieves adequate flexibility for application while maintaining resistance to blocking failures during storage and use.
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 a heat-activated pressure-sensitive adhesive with improved adhesive and blocking properties, enabling effective label production without a liner, as demonstrated by increased peel force and reduced blocking failures.
Implementation Method 1
heat-activated pressure-sensitive adhesive
Implementation Method 2
coating the adhesive composition on paper or plastic film
Data Source
AI summary
A composition having three components. The first component is from 20 to 80 wt% of a styrene-diene block copolymer having from 10-30 wt% polymerized units of styrene, wherein the block copolymer is present as a dispersion of copolymer in water, and the dispersion contains less than 5 wt% organic solvent based on total dispersion weight. The second component is from 0.5 to 20 wt% of a plasticizer. The third component is from 20 to 80 wt% of a tackifier.