Paper Lid Reverse-Taper Structure for Leak-Resistant Fit

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Solution Overview

Problem

Existing paper cups with paper lids suffer from leakage issues when inclined due to mismatched tapers between the cup and lid, and usability has not been adequately addressed in previous designs.

Innovation Solution

A paper lid design featuring a reverse-tapered portion that fits securely into a container, combined with a sealable drinking spout, air holes, and a holder for improved fit and sealability, utilizing a paper material with optional coatings for enhanced durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plastic lid is used to cover the paper cup, then the sealability is improved, but the environmental friendliness deteriorates

Engineering Contradiction:
ImprovesealabilityVSAvoidenvironmental impact
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material parameter from plastic to paper, and optimizes the geometric parameters (taper angle, wall thickness, flange dimensions) of the paper lid to achieve sealability comparable to plastic lids while maintaining environmental friendliness

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite structure combining paper material with waterproof coating or lamination to achieve both environmental friendliness and sealability, creating a paper-based composite lid that prevents liquid penetration

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If the paper cup and lid are both tapered forward, then the manufacturing is simplified, but the sealability deteriorates when the container is inclined

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidsealability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent inverts the taper direction of the lid wall relative to the cup, making the lid wall taper backward while the cup tapers forward. This creates an interference fit that prevents leakage when the container is inclined, while still allowing for simple manufacturing processes

Inventive Principle:
Principle #13The other way round (Inversion)

3Object-affected harmful factors

If a paper lid is used instead of plastic lid, then the environmental friendliness is improved, but the sealability deteriorates

Engineering Contradiction:
Improveenvironmental impactVSAvoidsealability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent optimizes geometric parameters including wall thickness, taper angle, and flange dimensions of the paper lid to achieve adequate sealability. The wall thickness is specifically controlled to prevent liquid penetration while maintaining the paper material's environmental benefits

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs waterproof coatings or laminations on the paper lid surface to create a composite structure that prevents liquid penetration. This allows the lid to maintain environmental friendliness while achieving sealability comparable to plastic lids

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3895999B1Paper cover and method for manufacturing paper cover
Publication Date: 2025.09.10 YAMADA CO LTD
  • EP3895999B1 patent drawingFigure 1A~1B
  • EP3895999B1 patent drawingFigure 2A~2B
  • EP3895999B1 patent drawingFigure 2C~2D

AI summary

In order to provide a paper lid with good usability, a paper lid includes a lid body portion that includes a paper material to be mounted on a container including an opening portion, a taper, and a curl portion, a first engaging portion that is provided in the lid body portion, includes a taper in the same direction as a direction of the taper, and engages with the curl portion from outside the curl portion, and a body portion side curl portion that is provided in the lid body portion and is positioned above the first engaging portion.