Sanitary Membrane Leaf Packet Adhesive Curing
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Solution Overview
Problem
In spiral-wound filtration elements, the adhesive-tape configuration at creases can weaken over time, leading to low-flow channels that trap organic material and promote bacterial growth, especially during frequent cleaning cycles, and the use of UV curing, pressure, and swelling solvents adds complexity and cost.
Innovation Solution
A membrane leaf packet with adhesive on the backside of the membrane, cured in contact with a non-stick protective sheet, eliminating the need for tape and reducing surface energy and roughness, thereby minimizing microbial biofilm formation and maintaining sanitary conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive-tape configuration is used at creases, then the adhesive is covered and handled easily, but the tape-adhesive bond weakens over time creating low-flow channels that trap organic material and promote bacterial growth
Solution Approach 1:
The patent removes the tape component from the adhesive-tape configuration, leaving only the adhesive applied to the backside of the membrane at the crease area. This extraction eliminates the interface between tape and adhesive that causes delamination and low-flow channel formation, while maintaining the adhesive's function of holding the membrane layers together during handling and operation.
Solution Approach 2:
The patent employs a removable non-stick protective sheet that is discarded after use. This protective sheet is applied over the adhesive during manufacturing to prevent contamination, then removed before the membrane element is put into service. This disposable approach ensures the adhesive surface remains clean and sanitary without requiring permanent protective structures.
2Reliability
If UV curing is used to cure adhesive, then adhesive curing is achieved, but cost and complexity increase due to photoinitiators and UV curing equipment
Solution Approach 1:
The patent replaces UV curing (an optical/chemical process requiring photoinitiators and UV equipment) with thermal curing or ambient curing of the adhesive. The adhesive is formulated to cure through heat treatment or natural drying, eliminating the need for UV curing systems, photoinitiators, and associated complex equipment while achieving adequate adhesive bonding.
Solution Approach 2:
The patent uses a disposable non-stick protective sheet that simplifies the curing process by preventing contamination during adhesive application and curing. The protective sheet is removed after curing, leaving a clean adhesive surface without requiring complex contamination control systems.
3Strength
If pressure and heat are used to fuse reinforcing strip, then structural strength is improved, but cost and complexity increase
Solution Approach 1:
The patent removes the reinforcing strip component entirely, relying on the adhesive applied to the membrane backside to provide sufficient structural strength. This extraction eliminates the need for separate reinforcing elements and their associated fusing processes, simplifying the manufacturing while maintaining adequate mechanical integrity.
Solution Approach 2:
The patent combines the functions of the reinforcing strip and adhesive into a single adhesive system. The adhesive serves both as the bonding agent for holding membrane layers together and as the structural reinforcement element, eliminating the need for separate reinforcing strips and their complex fusing processes.
4Reliability
If swelling solvent is used to solidify reverse osmosis layer, then membrane layer formation is achieved, but cost and complexity increase
Solution Approach 1:
The patent replaces the swelling solvent method (a chemical process requiring specialized equipment) with alternative membrane formation methods such as phase inversion, dry-jet wet spinning, or thermal curing. These alternative methods achieve the same membrane layer solidification without requiring swelling solvents, reducing equipment complexity and operational costs.
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 enhances sanitary properties by preventing bacterial growth and reducing surface roughness, maintaining cleanliness during service, and eliminating the need for UV curing, pressure, and swelling solvents, thus simplifying the filtration process.
Implementation Method 1
curing the adhesive in contact with the removable non-stick/protective sheet... the adhesive cures with chemical moieties preferentially oriented to minimize energy differences with the protective sheet... the resulting cured adhesive surface can have a lower surface energy than would be generated if the adhesive were covered by a tape
Data Source
AI summary
The disclosure relates to a membrane leaf packet, and a spiral membrane element including a plurality of such membrane leaf packets, including such elements exhibiting enhanced sanitary properties. Such membrane elements can be used for filtration, for example, in food-related fields, including filtering dairy, sugar and/or other liquid streams.