Medical Packaging Coating for Clean, Non-Resealing Seals

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Solution Overview

Problem

Existing packaging materials for medical use suffer from high residual solvent content, excessive adhesive application weight, reduced machine productivity, poor seal strength, and inability to prevent resealing after opening, which affects the quality and efficiency of medical packaging.

Innovation Solution

A packaging material coated with a release varnish over its entire surface and a sealing medium in a grid pattern, using a polyamide-based release varnish and ethylene-vinyl acetate copolymer dispersion, ensuring clean detachment and preventing resealing, while maintaining gas permeability for ethylene oxide sterilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hot melt adhesive is applied using solvent, then the packaging material can be bonded and sealed, but high proportion of residual solvent remains in the packaging material

Engineering Contradiction:
Improvebonding capabilityVSAvoidresidual solvent content
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the coating by using a polyamide-based release varnish instead of traditional solvent-based hot melt adhesive. This parameter change eliminates the need for high levels of residual solvent while maintaining bonding capability through the release varnish coating applied at 3-7 g/m².

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The release varnish coating is designed to be completely transferred to the counterpart during opening, effectively making it a single-use protective layer that ensures clean detachment while preventing resealing. This disposable approach eliminates the need for durable adhesive bonds that would require solvent for proper adhesion.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Strength

If high application weight of hot melt adhesive is used, then bonding strength is improved, but final product weight increases and residual solvent problem is exacerbated

Engineering Contradiction:
Improvebonding strengthVSAvoidfinal product weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent optimizes the coating weight parameter to 3-7 g/m², which is significantly lower than traditional hot melt adhesive applications (6-11 g/m² or higher). This parameter change achieves sufficient bonding strength through the release varnish mechanism while reducing final product weight and minimizing solvent absorption capacity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The release varnish acts as an intermediary layer between the paper packaging base material and the sealing surface. This intermediary provides the necessary bonding and sealing capabilities without requiring high adhesive application weights, thus reducing overall weight while maintaining bond strength.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If direct hot melt adhesive application is used, then machine speed is maintained, but thick hot melt adhesive layer leads to poor hot tack and reduced initial seal strength

Engineering Contradiction:
Improvemachine speedVSAvoidinitial seal strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The patent changes the coating thickness parameter by applying release varnish at a controlled weight of 3-7 g/m², creating a thin uniform layer rather than a thick adhesive layer. This parameter change enables fast machine operation while achieving adequate initial seal strength through the release varnish properties.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The release varnish is applied uniformly across the packaging surface, providing consistent local bonding properties throughout. This uniform local quality ensures reliable sealing performance at high machine speeds without the variability associated with thick adhesive layers.

Inventive Principle:
Principle #3Local quality

4Ease of operation

If packaging material is designed for clean detachment, then opening is simplified, but resealing becomes possible unless specifically prevented

Engineering Contradiction:
Improveopening easeVSAvoidresealing prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent extracts the bonding function from the paper substrate by applying a release varnish coating that completely transfers to the counterpart during opening. This extraction ensures clean detachment without paper fiber tearing while simultaneously preventing resealing, as the release varnish is completely removed from the original packaging surface.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The release varnish coating functions as a disposable bonding layer that is completely transferred to the counterpart upon opening. This single-use approach simplifies opening through clean detachment while inherently preventing resealing, as the bonding surface is completely removed with the coating transfer.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 solution provides a lightweight, efficiently producible packaging material with optimal seal strength, preventing resealing and allowing ethylene oxide sterilization, while minimizing solvent residues and ensuring high machine productivity.

Implementation Method 1

the release varnish ensures that the coating of the packaging base material, which consists of release varnish and sealing medium, can be completely detached from the packaging base material, i.e. from the paper, according to a first variant, without the paper fibers tearing

Methodology Applied
Scientific EffectRelease varnish adhesion reduction: Adhesive

Implementation Method 2

the sealing medium remains entirely on the counterpart with which the sealing medium was sealed during formation and/or closing of the container or packaging

Methodology Applied
Scientific EffectSealing medium adhesion: Adhesive

Implementation Method 3

The paper material used to produce the packaging material is plasma-treated according to the invention, which advantageously prevents fraying of the paper.

Methodology Applied
Scientific EffectPlasma treatment: Plasma

Data Source

PatentEP3749805B1Packaging material, method for producing said packaging material, and use thereof
Publication Date: 2025.08.20 HUHTAMAKI FLEXIBLE PACKAGING GERMANY GMBH & CO KG
  • EP3749805B1 patent drawingFigure 1~2

AI summary

The invention relates to a packaging material for medical purposes. The packaging material comprises a packaging base material having an outer paper surface, a release lacquer that coats an entirety of the outer paper surface, and a sealing medium that is applied on the release lacquer in a grid pattern. The invention further relates to a method for producing the packaging material and its use.