Shrink-Wrap Film with Tear-Initiating Cuts and Pull Tab

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Solution Overview

Problem

Existing shrink-wrap films for consumer products are difficult to remove cleanly and quietly, often requiring tools or significant force, and can damage the underlying packaging due to noisy perforations or unpredictable tear paths.

Innovation Solution

Non-crosslinked polyolefin (POF) and doped crosslinked POF films with strategically placed tear-initiating cuts and a tab that propagate straight, parallel tears when pulled, eliminating the need for perforations and reducing noise and effort in removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional shrink-wrap films are used, then the packaging is protected and sealed, but the films are difficult to remove and require significant force or tools

Engineering Contradiction:

ImproveEase of removalVSAvoidFilm strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The film is segmented into different functional zones: a strong seal portion that maintains packaging integrity and a tear-initiating portion with controlled weakness that enables easy opening. The tear-initiating cuts create designated opening paths that separate the opening function from the sealing function, allowing the film to be both strong and easy to remove.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Tear-initiating cuts are pre-formed in the film during manufacturing, creating predetermined opening paths before the product reaches the consumer. These pre-formed cuts eliminate the need for tools or significant force during removal, as the user simply needs to initiate tearing at the pre-weakened points.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If perforations are added to enable easy opening, then removal becomes easier, but noise increases and packaging may be damaged

Engineering Contradiction:

ImproveEase of openingVSAvoidNoise and damage

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

Instead of perforating the entire film, the weakness is localized to specific tear-initiating cuts at predetermined positions. The majority of the film maintains its full strength and integrity, preventing damage to the underlying packaging while enabling controlled opening at specific locations without generating noise from widespread perforations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention converts the potential harm of film strength (difficulty to open) into a benefit by creating controlled weakness points. The tear-initiating cuts create localized failure points that guide the tearing process along safe paths, preventing uncontrolled tearing that could damage packaging, while still enabling easy opening.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If the film is made easier to tear, then removal requires less force, but the tear paths become unpredictable

Engineering Contradiction:

ImproveForce required for removalVSAvoidTear path consistency

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The film's mechanical properties are modified locally at the tear-initiating cuts, creating zones of controlled weakness with different tensile strength and elasticity compared to the rest of the film. This parameter change enables predictable tear propagation along specific paths while maintaining overall film strength for packaging protection.

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 easy, controlled, and quiet removal of shrink-wrap films without tools, providing consistent tactile feedback and minimizing noise, while being a cost-effective alternative to other materials.

Implementation Method 1

When the tab is pulled, a tear forms at each of the first and second cuts and both tears propagate in straight, parallel lines in the machine direction of the shrink-wrap film

Methodology Applied

Scientific EffectFracture Mechanics: Fracture Mechanics

Implementation Method 2

heating the film to shrink wrap the film around the box, which creates high-strain areas in the machine direction of the film at edges of the box

Methodology Applied

Scientific EffectThermal Contraction: Thermal Contraction

Data Source

PatentUS11014706B2Opening configuration for shrink-wrapped package

Publication Date: 2021.05.25 APPLE INC

AI summary

Non-crosslinked polyolefin films or doped crosslinked polyolefin films (i.e., crosslinked polyolefin films that include a tear-alignment additive) may be used to shrink-wrap packages to create a wrapped package that is protected from tampering and damage but is also easy to open with little effort required by the customer. There is no need for perforations, and the films are quiet when torn, folded, cut, etc. Tear initiating cuts may be formed in the film. A tab may be placed over the film, and when the tab is pulled it applies enough force to start a pair of straight tears. The tears may be parallel or perpendicular to each other. The tears propagate in non-crosslinked polyolefin easily in the machine direction of the film as the tab continues to be pulled. In a doped crosslinked polyolefin, the tears propagate in the machine direction or perpendicular to the machine direction of the film.