Direct Adhesive Coating on Curved Surfaces

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Solution Overview

Problem

Adhesive sheets with resin layers face challenges in bending and handling due to predetermined thickness and hardness, making it difficult to join them to curved surfaces and requiring pre-cutting to fit specific workpieces, which complicates storage and application.

Innovation Solution

A method and apparatus that apply an adhesive resin coating to a workpiece with a predetermined width, followed by joining a reinforcing substrate with a width smaller than the coating using a joining roller or nozzle, allowing for flexible shaping and easy handling without pre-cutting the adhesive sheet.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pressure-sensitive adhesive sheet is applied to a curved surface using conventional methods, then the adhesive can be applied to the surface, but air bubbles remain trapped between the adhesive and the surface preventing proper adhesion

Engineering Contradiction:
Improveadhesion qualityVSAvoidair bubbles
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The adhesive sheet is pre-laminated to the curved surface in a controlled environment before final application, allowing air to be expelled during the lamination process rather than during final application. This preliminary bonding action prevents air bubble entrapment that would occur with conventional direct application methods.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A release film serves as an intermediary between the adhesive sheet and the curved surface during the lamination process. The release film allows the adhesive to be applied uniformly while preventing direct contact that would trap air bubbles, then is removed after bonding is established.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Area of stationary object

If a pressure-sensitive adhesive sheet is cut into a specific shape after application, then the adhesive can be applied to the entire surface, but time is required to cut and remove excess adhesive

Engineering Contradiction:
Improveadhesive coverage areaVSAvoidcutting time
Core Design Contradiction:
Area of stationary objectVSLoss of time

Solution Approach 1:

The adhesive sheet is pre-cut into the specific required shape before application to the curved surface. This preliminary shaping eliminates the need for post-application cutting and removal of excess adhesive, saving time while ensuring precise fit to the target surface area.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The adhesive sheet is pre-shaped to match the exact contour and dimensions of the target curved surface area. By creating a copy of the required shape beforehand, the adhesive can be applied directly without subsequent trimming or removal operations.

Inventive Principle:
Principle #26Copying

3Reliability

If a pressure-sensitive adhesive sheet is applied to a curved surface, then adhesion can be achieved, but the adhesive tends to peel off at the edges reducing adhesion

Engineering Contradiction:
Improveadhesion durabilityVSAvoidedge adhesion strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The lamination process applies dynamic pressure and heat that gradually increases from the center outward, allowing the adhesive to bond progressively across the surface. This dynamic application method ensures strong edge adhesion by maintaining pressure on the edges throughout the bonding process, preventing peeling.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The lamination process changes physical parameters including temperature and pressure during application. By controlling these parameters to increase gradually and maintain optimal levels at the edges, the adhesive achieves maximum bonding strength at the edges, preventing peeling that would occur with static application methods.

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

Enables direct adhesion to workpieces regardless of surface conditions, prevents air bubbles, and allows for easy storage and handling of the adhesive sheet, ensuring strong and uniform bonding.

Implementation Method 1

a heating unit configured to heat the pressure-sensitive adhesive sheet

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 2

a pressing unit configured to press the pressure-sensitive adhesive sheet on the curved surface

Methodology Applied
Scientific EffectMechanical pressure: Compression

Data Source

PatentEP3381991B1Method for applying pressure-sensitive adhesive sheet and device for applying pressure-sensitive adhesive sheet
Publication Date: 2020.09.09 NITTO DENKO CORP
  • EP3381991B1 patent drawingFigure 1
  • EP3381991B1 patent drawingFigure 2~3
  • EP3381991B1 patent drawingFigure 4~6

AI summary

A die coater 10 as a coating member directly applies an adhesive resin G to a joining portion of a workpiece W by a predetermined width while a holding table 1 holding the workpiece W placed thereon moves. A reinforcing substrate T supplied from an original master roll is joined to the resin G applied to the workpiece W while being pressed by a joining roller 15, and the reinforcing substrate T is cut by a predetermined length. That is, an adhesive sheet is directly formed on the workpiece W.