Hot Melt Membrane Spacers for Coating-Safe Printing

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Solution Overview

Problem

Existing spiral-wound membrane elements face issues with reduced flux and salt rejection due to damage from traditional printing methods that use UV or light-cured adhesives, which can impair the polyamide coating, and inefficiencies in spacer design leading to stress concentrations and reduced performance.

Innovation Solution

The use of thermally cured hot melt materials applied as edge and intermediate spacers on the membrane surface, which are designed to minimize damage and enhance printing speed, allowing for flexible and efficient spacer configurations that reduce stress concentrations and improve fluid flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If UV or light-cured adhesives are used for printing spacers on the membrane surface, then the spacers can be applied efficiently, but the polyamide coating of the membrane is damaged

Engineering Contradiction:

Improveprinting efficiencyVSAvoidmembrane coating damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the curing mechanism from UV/light-based to thermal curing. Hot melt adhesive is applied in a molten state and then cured by cooling and thermal treatment, completely avoiding UV or light exposure that damages the polyamide coating while still achieving efficient spacer application

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the photochemical curing system (UV/light) with a thermal system. The hot melt adhesive is applied at elevated temperature and cured through controlled cooling and thermal treatment, substituting the harmful optical energy with a controllable thermal process that does not damage the membrane

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If traditional feed spacer mesh is used, then flow distribution is maintained, but stress concentrations occur and membrane performance decreases

Engineering Contradiction:

Improveflow distributionVSAvoidmembrane performance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent transitions from uniform mesh spacers to localized printed spacers with varying patterns, densities, and heights. Different regions of the membrane surface receive customized spacer configurations that locally optimize flow distribution while reducing stress concentrations at critical areas

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent divides the continuous mesh spacer structure into discrete, segmented printed spacer features. These individual spacer elements are distributed across the membrane surface in specific patterns, maintaining flow distribution functions while eliminating the continuous stress concentration problems of traditional mesh

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If multi-pass UV or light cured ink jet processes are used to build spacer height, then precise spacer configuration is achieved, but the process time increases

Engineering Contradiction:

Improvespacer configuration precisionVSAvoidprinting process time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies the adhesive in a pre-molten state with the correct viscosity and flow characteristics before application. This preliminary preparation allows the material to be deposited in the desired height and configuration in a single pass, eliminating the need for multiple building passes required by UV-cured materials

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes the phase transition of hot melt adhesive from liquid (molten) to solid state. The adhesive is applied in liquid form, allowing easy flow and precise positioning, then rapidly solidifies upon cooling to achieve the final spacer configuration in one step, avoiding multi-pass processes

Inventive Principle:

Principle #36Phase transitions

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 hot melt spacers provide improved flux and salt rejection by avoiding damage to the membrane surface, enabling more efficient fluid flow and reducing operational costs through recyclability and faster printing processes.

Implementation Method 1

thermally cured hot melt materials applied as edge and intermediate spacers on the membrane surface

Methodology Applied

Scientific EffectThermal curing: Phase Change

Data Source

PatentUS20250222407A1Hot melt membrane spacers

Publication Date: 2025.07.10 AQUA MEMBRANES INC

AI summary

Hot melt printed spacer membrane elements offer the unique advantage of applying any pattern on the membrane surface to act as the feed spacer material. This technique also eliminates damage to the active surface of the membrane by avoiding photo curing, either UV, light or other wavelengths of energy. By printing narrow features, the bending moment at the membrane surface imparted by the printed feature will be less than the bending moment imparted by a wider printed feature, thereby minimizing damage to the sensitive membrane coating.