Laser Surface Marking of Polymeric Sheets for Durable Traceability
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Solution Overview
Problem
Current methods for imprinting information on polymeric sheets, such as flexographic ink printing and thermal ink transfer, face challenges with non-toxicity, abrasion resistance, and logistical issues, particularly in the food and pharmaceutical sectors, where stringent standards and increased reuse requirements complicate traceability and storage.
Innovation Solution
A method using a laser beam to locally modify the surface of polymeric sheets, creating durable markings without inks or ribbons, ensuring non-toxicity and preventing sheet adhesion during stacking, which includes setting a predefined pattern for marking and optionally creating surface hollows to prevent mutual adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexographic ink printing or thermal ink transfer is used to imprint information on polymeric sheets, then traceability information can be added, but the markings are not resistant to abrasion and chemical-physical agents, causing loss of information
Solution Approach 1:
The patent replaces mechanical/chemical printing systems (flexographic ink printing, thermal ink transfer) with a laser-based system. The laser beam directly modifies the polymeric sheet surface through ablation or melting, creating permanent markings without requiring inks or ribbons. This substitution eliminates the inherent weakness of ink-based markings being susceptible to abrasion and chemical agents, as the laser-marked features are integral to the sheet structure.
Solution Approach 2:
The patent utilizes laser parameters (wavelength, power, pulse duration, scanning speed) to control the marking process. By adjusting these parameters, the laser can create different types of surface modifications (ablation, melting, charring) that produce durable markings with varying depths and appearances. The marking depth and intensity can be precisely controlled to optimize both visibility and durability for different application requirements.
2Reliability
If conventional printing methods are used, then markings can be applied, but toxic inks may be used which do not comply with non-toxicity standards in food and pharmaceutical sectors
Solution Approach 1:
The patent replaces ink-based printing systems with a laser-based system that uses only energy to create markings. The laser beam interacts with the polymeric sheet material itself, vaporizing or melting portions to create permanent features. Since no external inks or chemical substances are applied, there is zero risk of toxic contamination, ensuring full compliance with non-toxicity standards for food and pharmaceutical applications.
Solution Approach 2:
The patent eliminates the need for consumable printing materials such as inks, ribbons, and printing plates. The laser system uses only energy from the laser beam, which is a non-consumable resource. This eliminates all associated toxicity concerns and reduces waste from disposable printing materials.
3Productivity
If polymeric sheets are stacked for storage and transport, then logistical efficiency is improved, but sheets adhere to each other due to suction or electrostatic effects, causing machine jamming
Solution Approach 1:
The patent applies local quality modification by creating specific surface features (hollows, ridges, or textured patterns) at particular locations on the sheet surface through laser treatment. These localized modifications create air pockets or reduce contact area between stacked sheets, preventing adhesion while maintaining the overall integrity and stackability of the sheets for efficient storage and transport.
4Reliability
If laser beam is used to mark polymeric sheets, then durable and non-toxic markings are achieved, but the process requires precise control of laser parameters to prevent excessive material removal
Solution Approach 1:
The patent employs periodic action by using pulsed laser beams instead of continuous irradiation. The laser operates in discrete pulses with controlled duration, frequency, and duty cycle. This allows precise control over energy delivery to the polymeric sheet, enabling the operator to achieve the desired marking depth without excessive material removal. The pulse timing and duration can be adjusted to match the thermal diffusion time in the material, confining the effect to the surface layer.
Solution Approach 2:
The patent implements feedback control by monitoring the marking process in real-time and adjusting laser parameters accordingly. Sensors detect the actual marking depth, surface temperature, or material removal rate, and this information feeds back to the laser control system to dynamically adjust power, pulse duration, or scanning speed. This closed-loop control ensures consistent marking quality and prevents excessive material removal even when processing conditions vary.
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 method provides durable, non-toxic markings that resist chemical and physical agents, ensuring traceability and reducing storage and production costs, while preventing sheet adhesion during stacking, thus enhancing operational reliability and reducing machine downtimes.
Implementation Method 1
a) striking at least one face of at least one polymeric sheet with a laser beam, with prolonged exposure of the sheet to the beam until the color of a surface portion struck by the beam changes
Implementation Method 2
striking at least one face of at least one polymeric sheet with a laser beam, with prolonged exposure of the sheet to the beam until the color of a surface portion struck by the beam changes
Implementation Method 3
striking at least one face of at least one polymeric sheet with a laser beam, with prolonged exposure of the sheet to the beam
Implementation Method 4
localized modification of at least one surface portion and the consequent surface alteration of the face
Data Source
Figure 1
Figure 2
AI summary
A method for processing polymeric sheets, which provides, in a step a., for striking at least one face of at least one polymeric sheet (1) with a laser beam for the localized modification of at least one surface portion of the sheet (1) and the consequent superficial alteration of the face.