Laser-Weldable Polymers Using Copper Phosphate Absorbers
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Solution Overview
Problem
Current laser-welding techniques for polymers face challenges in achieving stable welds for pale colors and transparent plastics due to limitations with existing absorbers like carbon black and other additives, which result in long process times and surface weld seams, and do not allow for efficient welding of polymers with low absorber concentrations.
Innovation Solution
Incorporating copper hydroxide phosphate and/or copper phosphate as the absorber in the laser-absorbent part, along with scattering additives in the laser-transparent part, to enhance weldability and strength, allowing for faster and more efficient laser welding of polymers with minimal absorber usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon black is used as absorber in laser-absorbent part, then absorption of laser light is improved, but colour variety is limited to black only
Solution Approach 1:
The patent changes the chemical composition parameter of the absorber from carbon black to copper hydroxide phosphate and copper phosphate compounds. These copper-based compounds have different optical properties that allow absorption of laser light while permitting pale colours and transparent systems, thus resolving the contradiction between absorption efficiency and colour variety.
2Adaptability or versatility
If absorber paste is applied in interlayer method, then welding of all colours including transparent plastics is enabled, but process complexity increases due to additional application step
Solution Approach 1:
The patent combines the absorber function with the polymer material itself by incorporating copper hydroxide phosphate and copper phosphate directly into the polymer formulation during manufacturing. This eliminates the need for separate absorber paste application steps, thus reducing process complexity while maintaining the capability to weld all colours including transparent plastics.
Solution Approach 2:
The absorber compounds are pre-incorporated into the polymer material during the manufacturing process before the actual welding operation. This preliminary incorporation ensures that the material is ready for welding without requiring additional absorber application steps, thereby simplifying the overall process.
3Adaptability or versatility
If TiO2 is used as absorber, then pale colours are enabled, but absorption strength is reduced leading to longer process times
Solution Approach 1:
The patent changes the absorber material from TiO2 to copper hydroxide phosphate and copper phosphate compounds. These copper-based compounds provide stronger laser light absorption compared to TiO2, enabling faster welding processes while still supporting pale colours and transparent systems.
Solution Approach 2:
The patent uses composite copper-based compounds (hydroxide phosphate and phosphate) that combine the benefits of strong laser absorption with compatibility for pale colours and transparent polymers, overcoming the limitations of single-material absorbers like TiO2.
4Productivity
If strongly absorbent additives are used in laser-absorbent part, then welding speed is improved, but stable welding cannot be achieved due to plastic melting
Solution Approach 1:
The patent optimizes the concentration parameter of the copper hydroxide phosphate and copper phosphate absorbers to achieve a balance between absorption strength and weld stability. The specific dosage ranges provided ensure sufficient laser absorption for fast welding while preventing excessive heat generation that would cause plastic melting and unstable welding.
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 significantly improves welding speed and strength, enabling efficient laser welding of pale colors and transparent plastics with reduced absorber amounts, achieving welds that are stronger and faster than conventional methods, while maintaining processability and color variability.
Implementation Method 1
The laser beam passes through the transparent plastic element and is absorbed by the second, opaque plastic element. This causes the opaque plastic element to warm
Implementation Method 2
The lasers used are usually diode lasers or Nd:YAG lasers having wavelengths between 808-1100 nm
Implementation Method 3
the laser-absorbent part comprises, as absorber, a copper hydroxide phosphate and/or copper phosphate
Implementation Method 4
a scattering additive, such as, for example, TiO2, CaCO3 or MgCO3, or other white pigments or fillers, etc., known to the person skilled in the art can optionally be added to the laser-transparent part
Data Source
AI summary
The present invention relates to laser-weldable polymers which consist of a laser-transparent part and a laser-absorbent part and can be welded to one another by means of laser light and are distinguished by the fact that the laser-absorbent part comprises, as absorber, copper hydroxide phosphate and/or copper phosphate.