Low Anisotropy Pressure-Sensitive Adhesive Melt Strip Control
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Solution Overview
Problem
Current methods for producing pressure-sensitive adhesives (PSAs) do not achieve high enough anisotropy, which limits their specialized applications due to insufficient control over the stretching process during coating.
Innovation Solution
The method involves controlling the stretching process of the free melt plume in PSA production using an effective ratio Γ, characterized by the effective time Δt and stretching rate R, to optimize anisotropy generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the stretching process of the free melt plume is not controlled, then the production process is simple, but the anisotropy of the PSA is insufficient
Solution Approach 1:
The patent applies parameter changes by controlling the stretching process through the ratio Γ (Gamma) of stretching rate R to effective time Δt. By adjusting these parameters during the coating process, the anisotropy of the PSA can be precisely controlled without requiring fundamentally new equipment or processes.
Solution Approach 2:
The patent implements dynamics by making the stretching process controllable and adjustable during production. The stretching rate and effective time can be dynamically modified to achieve desired anisotropy levels, allowing the process to adapt to different production requirements.
2Manufacturing precision
If the stretching rate is increased to maximize anisotropy, then molecular orientation is improved, but the effective time for stretching is reduced
Solution Approach 1:
The patent resolves this contradiction by controlling the ratio Γ = R/Δt rather than simply increasing R. This allows optimization of both stretching rate and effective time by adjusting their relationship, ensuring maximum molecular orientation within the available processing time.
Solution Approach 2:
The patent applies preliminary action by pre-heating the PSA to its melting point before the stretching process. This preparation ensures the material is in the appropriate state for stretching, maximizing the effectiveness of the subsequent stretching process within the limited time available.
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
This approach enables the production of PSAs with increased anisotropy, enhancing their mechanical and adhesive properties for specific applications by maximizing molecular orientation and chain stretching.
Implementation Method 1
Within any processing process, the PSA system to be processed is typically exposed to a flow. Depending on the throughput and geometry of the space occupied by the PSA system or the space made available to the PSA system, flow profiles arise which are based on shear flows and/or expansion flows to varying degrees.
Implementation Method 2
One result of such deformation is the formation of oriented polymer chains. The oriented state is associated with structural anisotropy.
Data Source
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AI summary
The invention relates to a method for producing pressure-sensitive adhesives that have low or no anisotropy, the process elements including an adhesive supply system, an application unit and a placement element. A melt strip of the pressure-sensitive adhesive is produced between the outlet of the application unit and the point of placement on the placement element and is stretched. The invention is characterized by controlling the stretching of the pressure-sensitive adhesive in the free melt strip by adjusting an effective ratio G which is defined as the ratio of the effective time ?t of the stretching to the stretching rate R, and which is adjusted to a value of at least 0.006 s2 or to a value of not more than 0.004 s2. The effective time ?t is defined by the formula 2Lr/[vstrip(1 +r)] wherein L is the length of the melt strip, r is the stretching ratio and vstrip is the speed of the melt strip, and the stretching rate R is defined as a temporal derivative of the stretching ratio r.