Medical Cap Variable-Thickness Wall for Leak-Resistant Sealing

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Solution Overview

Problem

The existing medical caps with rubber stoppers suffer from airtightness issues due to clearances formed at notched portions, leading to potential liquid leakage and contamination.

Innovation Solution

A medical cap design featuring a tubular inner wall with varying thicknesses in the radial direction, including thin and thick portions arranged circumferentially, combined with a tubular mouth portion using a thermoplastic resin, and a manufacturing method involving heating to ensure contact between internal and external contact portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the internal wall is provided with a notched portion to facilitate deformation, then the ease of manufacture is improved, but the airtightness deteriorates due to clearance formation between the inner stopper and elastic stopper body

Engineering Contradiction:
Improveease of deformationVSAvoidairtightness
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The inner wall is designed with localized thin portions at specific positions rather than being uniformly thin throughout. These thin portions are strategically placed to enable deformation at critical locations while maintaining sufficient thickness elsewhere to prevent clearance formation and maintain airtightness between the inner stopper and elastic stopper body.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The inner wall thickness is segmented into different regions: thin portions for deformation and thick portions for maintaining structural integrity and airtightness. This segmentation allows the wall to perform multiple functions - deforming where needed while preventing clearance formation in other areas.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If the inner wall is made thinner to facilitate deformation, then the ease of manufacture is improved, but the structural strength deteriorates potentially compromising seal integrity

Engineering Contradiction:
Improveease of deformationVSAvoidstructural strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The inner wall employs non-uniform thickness distribution with thin portions localized at deformation-required positions and thick portions at positions requiring structural support. This ensures adequate strength is maintained in critical areas while enabling deformation where needed.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The wall structure is divided into functional segments: thin-walled sections for deformation and thick-walled sections for structural support. This segmentation allows the structure to be both deformable and strong simultaneously by assigning different thickness characteristics to different functional zones.

Inventive Principle:
Principle #1Segmentation

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

Prevents a decrease in airtightness, maintaining seal integrity and preventing liquid leakage and contamination.

Implementation Method 1

a step of changing the medical cap and the mouth portion from a state in which an internal contact portion which is disposed on an outer circumference surface of the mouth portion is separated from an external contact portion which is disposed on an inner circumferential surface of the outer wall to a state in which the internal contact portion is in contact with the external contact portion by heating the medical cap and the mouth portion which have been combined

Methodology Applied
Scientific EffectThermal softening of thermoplastic resin: Heating

Data Source

PatentEP4643839A1Medical cap, medical container, and production method for medical container
Publication Date: 2025.11.05 OTSUKA PHARMACEUTICAL FACTORY INC
  • EP4643839A1 patent drawingFigure 1A~1B
  • EP4643839A1 patent drawingFigure 2~3
  • EP4643839A1 patent drawingFigure 4~5

AI summary

A medical cap includes a stopper which is arranged inside a tubular mouth portion that forms an opening and a case. The case includes a tubular inner wall which is arranged between the stopper and the mouth portion in a state of being in contact with the stopper and the mouth portion and a tubular outer wall which surrounds the inner wall via a tubular space that houses the mouth portion. The inner wall includes a thin portion and a thick portion which are different from each other in thickness in a radial direction of the case. The thin portion and the thick portion are arranged in a circumferential direction of the case.