Laser-Weldable Polyester Composition for Uniform Transmittance
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Solution Overview
Problem
Achieving high and uniform laser transmissivity in laser weldable materials is challenging, particularly in achieving strong welding strength while maintaining consistent transmittance across different locations in molded products.
Innovation Solution
The compositions include one or more 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 transmittance and enhanced bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If amorphous sections and nucleating agents are added to improve laser transmittance, then laser beam scattering is reduced, but achieving uniform laser transmittance across the material remains challenging
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific cyclic carbonate monomers (epoxide groups) into the polymer structure. This chemical modification alters the material's optical properties to achieve both high laser transmittance and uniformity, resolving the contradiction between improving transmittance and maintaining uniformity.
Solution Approach 2:
The patent creates a composite polymer system combining polyesters with cyclic carbonate monomers containing epoxide groups. This composite structure leverages the complementary properties of the components to achieve high laser transmittance while maintaining uniform optical properties throughout the material.
2Strength
If conventional polyester compositions are used, then material availability is good, but welding strength is insufficient
Solution Approach 1:
The patent modifies the polyester composition by incorporating cyclic carbonate monomers with epoxide groups, changing the chemical parameters to enhance welding strength while maintaining compatibility with conventional manufacturing processes and material availability.
3Manufacturing precision
If laser transmissive parts are designed for laser welding, then precise control of welding area is achieved, but surrounding materials may be damaged by laser heat
Solution Approach 1:
The patent optimizes the optical parameters of the polyester material by incorporating cyclic carbonate monomers, which enhance laser transmittance and allow for more precise heat localization at the weld interface, thereby reducing thermal damage to surrounding materials while maintaining precise welding area control.
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, achieving strong welding strength and improved uniformity in laser weldable products.
Implementation Method 1
the laser light is turned into thermal energy as it is absorbed by the lower joining partner
Implementation Method 2
the weld is formed as intense laser light rapidly heats the material
Implementation Method 3
some of the thermal energy is transferred to the upper layer in order for melting to occur in both parts
Implementation Method 4
The heat created at the interface creates a molten weld seam and the two plastics are fused
Data Source
Figure 1~3
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.