UV Absorbent Ink Security Marking on Non-Brightened Carton

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Solution Overview

Problem

Existing methods for applying invisible security marks on packaging materials face interference from UV curable overprint varnishes containing optical brighteners, leading to visibility issues and hardware problems like gloss differential and inkjet nozzle clogging, especially on non-optically brightened carton stock.

Innovation Solution

Printing with UV-absorbent ink on carton stock without optical brighteners, followed by a UV curable varnish that fluoresces under UV illumination, ensuring the security mark remains hidden until revealed under UV light, and optionally using a transparent UV fluorescent sheet for enhanced security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If UV curable overprint varnish containing optical brighteners is applied to protect the packaging surface, then the durability and scuff resistance of the surface is improved, but the UV fluorescence of the security marks is interfered with and optical brighteners create visibility issues

Engineering Contradiction:

Improvesurface durabilityVSAvoidUV fluorescence interference

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

Instead of making the security mark fluorescent to stand out against the varnish, the invention inverts the approach by making the security mark UV-absorbing (dark) so it appears as a negative image against the fluorescent background of the varnish. This allows the varnish to be applied without interfering with the security mark's visibility under UV light.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention uses materials that change their optical properties under different lighting conditions. The security mark uses UV-absorbing ink that appears invisible under normal light but creates a dark pattern under UV illumination, while the varnish contains optical brighteners that fluoresce under UV light, creating a contrasting background that makes the security mark visible.

Inventive Principle:

Principle #32Color changes

2Ease of manufacture

If digital printing of radiation curable varnish is used to apply hidden information, then the security mark can be applied, but gloss differential becomes visible to the unaided eye and inkjet nozzles clog due to high viscosity and crosslinking

Engineering Contradiction:

Improvesecurity mark applicationVSAvoidgloss differential visibility

Core Design Contradiction:

Ease of manufactureVSDifficulty of detecting and measuring

Solution Approach 1:

The invention inverts the traditional approach by making the security mark appear as a dark pattern (negative image) rather than a light pattern. This allows the use of standard printing methods without creating visible gloss differentials, as the security mark is detected through UV fluorescence patterns rather than visual inspection of the printed varnish itself.

Inventive Principle:

Principle #13The other way round (Inversion)

3Difficulty of detecting and measuring

If UV absorbing ink is printed on substrate with optical brighteners to create negative image, then the security mark is visible under UV light, but this approach is not feasible on carton stock that does not contain optical brighteners

Engineering Contradiction:

Improvesecurity mark visibilityVSAvoidsubstrate compatibility

Core Design Contradiction:

Difficulty of detecting and measuringVSAdaptability or versatility

Solution Approach 1:

The invention makes the UV-absorbing security mark compatible with both optically brightened and non-optically brightened substrates by applying the fluorescent varnish as a universal background layer. This varnish layer provides the fluorescent background needed for the negative image effect regardless of whether the underlying substrate contains optical brighteners, thus achieving universality across different packaging materials.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 robust, uniform, and secure method for embedding information on non-optically brightened substrates, resistant to removal and visible only under UV light, enhancing authentication and counterfeiting prevention.

Implementation Method 1

information (e.g. text, logos, numbers, or barcodes) is printed using a UV-absorbent ink onto the substrate

Methodology Applied

Scientific EffectUV absorption: Absorption (EM radiation)

Implementation Method 2

a UV curable varnish that fluoresces under UV illumination is applied

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS9162513B2Method of authenticating an item

Publication Date: 2015.10.20 AUTHENTIX INC

AI summary

A method of authenticating an item with a security mark includes providing a substrate (100); printing the security mark on the substrate with invisible ultraviolet (UV) absorbing ink (102); applying a coating comprised of UV fluorescent varnish (104) over the security mark and substrate; illuminating an area comprising the security mark and coating with UV light; identifying a reduced fluorescence image of the security mark; comparing the reduced fluorescence image with the security mark; and authenticating the item if the reduced fluorescence image matches the security mark.