Core-Sheath Filament Adhesive for Complex Substrates

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Solution Overview

Problem

Traditional adhesive transfer tapes require die-cutting, leading to waste and limitations in applying adhesives to complex or irregular surfaces, and they often necessitate the use of release liners, which are not ideal for precise or intricate applications.

Innovation Solution

The development of core-sheath filaments with a non-tacky sheath and an adhesive core, where the sheath has a low melt flow index and the core is a polyisobutylene polymer, allowing for precise deposition and handling without the need for release liners or die-cutting, enabling printing on thin or complex substrates with reduced waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If adhesive transfer tapes are used, then adhesive application is simple, but die-cutting is required leading to waste and limitations in applying to complex surfaces

Engineering Contradiction:
Improveadhesive application simplicityVSAvoidmaterial waste from die-cutting
Core Design Contradiction:
Ease of operationVSLoss of substance

Solution Approach 1:

The invention changes the physical state and delivery form of the adhesive from pre-cut tape to a dispensable hot-melt composition delivered through a nozzle, eliminating the need for die-cutting and enabling application to complex surfaces

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

A non-tacky sheath material serves as an intermediary that encapsulates the adhesive core, allowing the adhesive to be handled and dispensed without premature adhesion, replacing the function of release liners

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If release liners are used with adhesive tapes, then adhesive handling is easier, but precise or intricate applications are limited

Engineering Contradiction:
Improveadhesive handlingVSAvoidprecision for intricate applications
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The invention extracts the adhesive from the tape format and delivers it directly through a nozzle as a hot-melt composition, eliminating release liners entirely and enabling precise control for intricate applications

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical tape-and-liner system with a thermal processing system where the adhesive is melted, dispensed, and applied with precision control

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If traditional adhesive tapes are used, then adhesive delivery is straightforward, but application to thin or complex substrates is difficult

Engineering Contradiction:
Improveadhesive deliveryVSAvoidability to print on complex substrates
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The invention introduces dynamic control through programmable nozzle movement and temperature control, allowing the adhesive application process to adapt to complex substrate geometries and patterns

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the adhesive from a solid tape to a hot-melt composition that can be precisely controlled in terms of temperature, flow rate, and deposition pattern, enabling application to diverse substrates

Inventive Principle:
Principle #35Parameter changes

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 solution provides a hot-melt processable adhesive system that can be used in FFF for precise and controlled adhesive placement on complex surfaces with minimal waste and no need for post-processing, offering high barrier properties and design flexibility.

Implementation Method 1

an adhesive core, wherein the adhesive core comprises: a polyisobutylene polymer having an average weight average molecular weight of 125000 grams per mole (g/mol) to 800000 g/mol

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

a non-tacky sheath, wherein the non-tacky sheath exhibits a melt flow index of less than 15 grams per 10 minutes (g/10 min)

Methodology Applied
Scientific EffectTackiness control:

Implementation Method 3

providing a high barrier to air and moisture which is beneficial in many applications

Methodology Applied
Scientific EffectBarrier properties:

Data Source

PatentEP4017930B1Core-sheath filaments including polyisobutylene compositions and methods of printing the same
Publication Date: 2023.08.16 3M INNOVATIVE PROPERTIES CO
  • EP4017930B1 patent drawingFigure 1~2

AI summary

Provided are amorphous polyolefin compositions that can be dispensed digitally as the core in a core-sheath construction. These formulations provide dependable adhesion to both polar and non-polar surface in addition to providing a high barrier to air and moisture which is beneficial in many applications. These formulations and the method of processing these formulations provide many benefits, including low VOCs, avoiding die cutting, design flexibility, achieving intricate nonplanar bonding patterns, printing on thin and/or delicate substrates, and printing on an irregular and/or complex topography, no need for release liners or low-adhesion backsize, and no need for a post-processing step.