TCDDM Copolyester Composition for Uniform Laser Welding
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Solution Overview
Problem
Achieving high and consistent laser transmissivity in laser weldable materials is challenging, particularly in achieving uniform transmittance while maintaining strong welding strength.
Innovation Solution
Compositions comprising inorganic fillers, copolymers derived from tricyclodecane dimethanol (TCDDM) and terephthalic acid, and polyesters such as polybutylene terephthalate (PBT), with TCDDM content between 1 wt% and 70 wt%, ensuring consistent light transmittance across different locations and enhanced bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If amorphous sections and nucleating agents are added to improve laser transmittance, then laser transmittance is improved, but uniformity of laser transmittance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by introducing TCDDM as a specific comonomer in copolyester compositions. This parameter change achieves both high laser transmittance (≥80% at 1064nm wavelength) and uniform transmittance distribution throughout the molded article, resolving the contradiction between improving transmittance and maintaining uniformity.
Solution Approach 2:
The patent creates a composite material system consisting of copolyester resins containing TCDDM units combined with specific inorganic fillers (such as TiO2, SiO2, Al2O3) in controlled amounts. This composite approach enables the material to achieve high laser transmittance while maintaining structural uniformity and consistency throughout the molded article.
2Manufacturing precision
If laser transmittance is increased to improve welding quality, then welding quality is improved, but welding strength deteriorates
Solution Approach 1:
The patent optimizes the TCDDM content parameter within a specific range (0.1-10 mol% in the copolyester) to achieve the optimal balance between laser transmittance and welding strength. This parameter optimization ensures that sufficient laser energy passes through the first article to weld the second article while maintaining the structural integrity and strength of the welded assembly.
Solution Approach 2:
The patent introduces inorganic fillers with specific laser absorption characteristics at controlled concentrations (0.1-10 wt% TiO2, 0.1-5 wt% SiO2, 0.1-5 wt% Al2O3) to create local variations in laser energy absorption. This enables precise control of the welding zone where energy is concentrated at the interface between articles while keeping the bulk material transparent to laser energy, thus achieving both high welding quality and strong welds.
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 compositions provide consistent light transmittance with a maximum 12% difference across various locations and achieve strong welding strengths, exceeding the bonding strength of comparative examples without TCDDM-modified polyesters.
Implementation Method 1
the laser light is turned into thermal energy as it is absorbed by the lower joining partner
Implementation Method 2
intense laser light rapidly heats the material. The beam of laser—light amplification by stimulated emission of radiation—is a single-phase light of a single wavelength with a low beam divergence and high energy content and thus will create heat when it strikes a surface
Implementation Method 3
some of the thermal energy is transferred to the upper layer in order for melting to occur in both parts
Data Source
AI summary
Laser weldable compositions are provided which in various examples include a tricyclodecane dimethanol-modified copolymer, a terephthalate-type polyester and an inorganic filler. Compared with compositions without the tricyclodecane dimethanol-modified copolymer, the compositions of the invention have improved, uniform laser transmittance, thereby welded products including the compositions have improved bonding strength and require stronger tensile strength to be torn apart.