Thermoplastic Marking via UV Laser Absorption

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Solution Overview

Problem

Current methods for marking thermoplastic compositions with lasers face challenges such as inconsistent marks due to low absorption, damage to underlying materials, and difficulty in creating light-colored marks on transparent compositions, especially when these materials are used in applications like automotive glazing or electronic devices where surface confinement and minimal topography change are desired.

Innovation Solution

A method involving thermoplastic compositions that absorb light with wavelengths less than or equal to 500 nanometers, allowing for the generation of light-colored marks through thermal interactions using laser beams, which can be customized for visibility and durability, and enabling laser welding of components without damaging underlying materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If 1064 nm laser light is used to mark transparent thermoplastic compositions, then marking capability is achieved, but inhomogeneous interaction and localized superheating occur due to low absorption

Engineering Contradiction:

Improvemark qualityVSAvoidmark consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the laser wavelength parameter from 1064 nm to wavelengths less than 500 nm (such as 355 nm or 266 nm), which fundamentally alters the absorption characteristics of the thermoplastic material. This parameter change enables homogeneous interaction and consistent mark quality without localized superheating.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal interaction mechanism (heating-based marking) with a photochemical interaction mechanism (cold marking). This substitution eliminates the problems of inhomogeneous heating and localized superheating by using photochemical reactions that occur uniformly throughout the irradiated area.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If carbon black or near infrared absorbing pigments are added to increase absorption, then mark quality improves, but visible transmission decreases and haze increases

Engineering Contradiction:

Improvemark qualityVSAvoidvisible transmission

Core Design Contradiction:

Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent changes the operating wavelength parameter from the near infrared region (1064 nm) to the visible/UV region (less than 500 nm). This allows the use of thermoplastic compositions with high visible transmission, as these materials naturally absorb strongly in the UV/blue region without requiring carbon black or other absorbing additives that would reduce visible transmission.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If ultraviolet lasers are used for cold marking, then thermal effects are minimized, but the laser beam passes through the substrate and damages underlying materials

Engineering Contradiction:

Improvethermal effectVSAvoiddamage to underlying materials

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an absorbing additive (such as carbon black, titanium dioxide, or zinc oxide) as an intermediary layer within the thermoplastic composition. This intermediary absorbs the ultraviolet laser energy and converts it to localized thermal energy, creating a controlled thermal effect that confines the marking process to the intended area and prevents damage to underlying materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates local quality by incorporating absorbing additives at specific locations within the thermoplastic composition (such as at the surface or at the interface between layers). This localized absorption ensures that thermal effects are confined to specific regions, enabling precise marking without affecting the entire substrate or underlying materials.

Inventive Principle:

Principle #3Local quality

4Illumination intensity

If swelling from void formation is used to create light colored marks, then light colored marks are achieved, but mark durability is poor due to easy compression of voids

Engineering Contradiction:

Improvemark colorVSAvoidmark durability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent utilizes controlled phase transitions (such as melting and resolidification) of the thermoplastic material during laser marking. This creates durable light-colored marks through structural changes in the polymer matrix rather than through void formation, significantly improving mark durability while maintaining the desired light color appearance.

Inventive Principle:

Principle #36Phase transitions

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

This approach allows for the creation of customizable, machine-readable light-colored marks on transparent and opaque thermoplastics with minimal profile change, ensuring durability and preventing damage to underlying components, while enabling laser welding with precise thermal control.

Implementation Method 1

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

allowing for the generation of light-colored marks through thermal interactions using laser beams

Methodology Applied

Scientific EffectThermal interaction: Heating

Implementation Method 3

enabling laser welding of components without damaging underlying materials

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Implementation Method 4

The heat is conducted to the first layer, which melts and a weld is created upon re-solidification of both components

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 5

Depending on the composition and/or the lasering parameters, the heat generated either causes a char, i.e., carbonization, to form a dark mark

Methodology Applied

Scientific EffectCarbonization: Pyrolysis

Implementation Method 6

or, alternatively a swelling from the formation of voids just below the surface and yields a light colored mark on a dark background, i.e., foaming

Methodology Applied

Scientific EffectFoaming: Foam

Data Source

PatentUS9168696B2Marked thermoplastic compositions, methods of making and articles comprising the same, and uses thereof

Publication Date: 2015.10.27 SHPP GLOBAL TECH BV

AI summary

In an embodiment, a method of inscribing a substrate comprises contacting the substrate with a laser beam to generate a mark, wherein the mark results from increasing the reflectivity of the thermoplastic material, wherein the substrate comprises a composition comprising a non-reflective thermoplastic material. In an embodiment, a method for generating a mark on an article comprises bonding a first component to a second component with a laser beam having a wavelength of greater than or equal to 800 nanometers, wherein the first component composition comprises a thermoplastic composition absorbing light having a wavelength of less than or equal to 500 nanometers and wherein the second component comprises a thermoplastic composition absorbing light having a wavelength of greater than or equal to 800 nanometers.