Curled Container Flange Structure for Stable Heat Sealing and Opening

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Solution Overview

Problem

Existing containers for food and beverages experience deformation of the flange part during sealing and opening, leading to poor fitting and openability issues, especially under strong sealing conditions.

Innovation Solution

A container design featuring a flange part with a first curl portion and a second curl portion bonded at one location, creating a space inside the second curl portion, which acts as a cushion during sealing, and a step portion to stabilize the outer diameter and facilitate easy opening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the flange part is formed with a curl shape to improve sealing contact, then the seal member bonding is enhanced, but the flange part deforms during sealing causing outer diameter change and poor lid fitting

Engineering Contradiction:
Improveseal member bonding strengthVSAvoidouter diameter dimensional stability
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The flange part is segmented into multiple functional zones: a first curl portion for seal contact, a bonding portion for structural integrity, and a second curl portion forming a hollow space for cushioning. This segmentation allows each zone to perform its specific function without interfering with the outer diameter stability required for lid fitting.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the flange part are given different structural properties: the first curl portion has a curled shape for sealing contact, the bonding portion provides structural support, and the second curl portion creates a hollow space for cushioning during sealing. This local differentiation resolves the contradiction by allowing deformation in specific zones while maintaining overall dimensional stability.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If the flange part is pressed flat to reduce deformation, then the outer diameter stability improves, but the sealing contact and openability are deteriorated

Engineering Contradiction:
Improveouter diameter dimensional stabilityVSAvoidseal member openability
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The flange part is divided into functional segments where the first curl portion maintains contact with the seal member for opening, the bonding portion ensures structural integrity, and the second curl portion with hollow space provides cushioning. This segmentation enables both dimensional stability and ease of opening.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hollow space in the second curl portion acts as a pre-formed cushion that absorbs sealing load before it reaches the flange structure. This beforehand cushioning prevents excessive deformation while maintaining the curl shape needed for easy opening.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If strong sealing is applied to resin cups, then the sealing strength is sufficient, but the seal member cannot be opened easily under the same sealing conditions for paper cups

Engineering Contradiction:
Improvesealing strengthVSAvoidseal member openability
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The hollow space in the second curl portion serves as a pre-designed cushion zone that absorbs sealing load. This allows strong sealing to be applied without making the seal member difficult to open, as the cushion space prevents excessive bonding strength that would hinder opening.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The flange part structure changes the effective parameters of sealing: the hollow space modifies the pressure distribution and bonding characteristics, allowing strong sealing under controlled conditions while maintaining ease of opening through the curl portions that can deform to initiate peeling.

Inventive Principle:
Principle #35Parameter changes

4Strength

If the flange part is given a curl shape to facilitate seal member bonding, then the sealing contact is improved, but the flange part deforms during opening making stable opening impossible

Engineering Contradiction:
Improveseal member bonding strengthVSAvoidflange part shape stability during opening
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The flange part is segmented into a first curl portion that maintains shape for seal contact, a bonding portion for structural support, and a second curl portion with hollow space for cushioning. This segmentation allows the first curl to remain stable while the second curl absorbs deformation during opening.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the flange have different structural qualities: the first curl portion maintains its shape for stable seal contact, while the second curl portion with hollow space is designed to deform in a controlled manner during opening, providing local flexibility without compromising overall stability.

Inventive Principle:
Principle #3Local quality

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 design suppresses deformation of the flange part during sealing and opening, allowing for stable and easy opening even under strong sealing conditions by forming a notch for easy peeling.

Implementation Method 1

a seal member that has a thermoplastic resin to be bonded to an upper surface of the flange part by heat sealing

Methodology Applied
Scientific EffectHeat sealing: Melting

Implementation Method 2

the space works as a cushion during the heat sealing of the seal member (springback effect)

Methodology Applied
Scientific EffectSpringback effect: Elasticity

Data Source

PatentEP4722117A1Container and container manufacturing method
Publication Date: 2026.04.08 TOKAN KOGYO CO LTD
  • EP4722117A1 patent drawingFigure 1
  • EP4722117A1 patent drawingFigure 2
  • EP4722117A1 patent drawingFigure 3~4

AI summary

A container includes: a cylindrical body part that is formed from a body member; a flange part that is formed by rolling one end of the body member outward; a bottom part that is formed from another end of the body member and a bottom member; and a seal member that has a thermoplastic resin to be bonded to an upper surface of the flange part by heat sealing. The flange part includes a first curl portion located on an outermost circumference of the body part in a radial direction, and a second curl portion overlapping with the first curl portion on an inside of the first curl portion. The flange part also includes a bonding portion that bonds the first curl portion and the second curl portion to each other in at least one location in a cross-sectional view in the radial direction, and has a space inside the second curl portion, the space having a thickness equal to or larger than a thickness of the body member.