Laser Welding Bonding Material for Stronger Polypropylene Joints
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Solution Overview
Problem
Laser welding efficiency is reduced in plastic materials containing additives due to energy dispersion and absorption, particularly in those with high crystallinity, leading to decreased joining strength and reliability.
Innovation Solution
A joining material for laser welding is developed, comprising a polypropylene resin with a specific melt index and a needle-like inorganic filler with an optimized aspect ratio, which minimizes energy dispersion and enhances mechanical properties, allowing for effective laser welding with improved strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plastic materials containing additives such as organic and inorganic fillers are used to reinforce physical properties, then mechanical strength is improved, but laser welding efficiency is reduced due to energy dispersion and absorption
Solution Approach 1:
The invention changes the physical and chemical parameters of the polymer matrix by selecting specific polyolefin resins with controlled melt indices (3-300 g/10 min) and incorporating needle-like inorganic fillers with optimized aspect ratios (5:1 to 50:1). These parameter changes enable the material to maintain high mechanical strength while achieving adequate laser transmission for efficient welding.
Solution Approach 2:
The invention creates a composite material system combining polyolefin resin matrix with needle-like inorganic fillers. This composite structure allows the material to simultaneously achieve enhanced mechanical properties from the filler reinforcement and sufficient laser transmission by optimizing the filler geometry and distribution, thus resolving the contradiction between strength and welding efficiency.
2Strength
If plastic materials with high crystallinity are used to improve mechanical properties, then strength is enhanced, but laser welding efficiency is reduced due to energy scattering and absorption
Solution Approach 1:
The invention optimizes the crystallinity parameter of the polyolefin resin within a specific range (30-80%) to balance mechanical strength and laser transmission. By controlling crystallinity rather than maximizing it, the material maintains structural integrity while reducing excessive energy scattering and absorption during laser welding.
3Device complexity
If a simple laser welding process is used to join plastic parts, then manufacturing complexity is reduced, but joining efficiency is insufficient when additives are present
Solution Approach 1:
The invention modifies the material parameters (polymer type, melt index, filler aspect ratio) to enable simple laser welding processes to achieve high joining efficiency. The optimized material composition allows the laser beam to transmit effectively through the material despite the presence of additives, maintaining process simplicity while improving joining efficiency.
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 joining material achieves excellent mechanical strength, flexural modulus, and impact resistance, enabling efficient laser welding with reduced energy scattering and improved product reliability, suitable for various applications including automotive and electronic devices.
Implementation Method 1
irradiating with a laser to form a welding region in a region where the joining material and the material to be joined are laminated
Implementation Method 2
there is a problem in that the these additives greatly reduce the joining efficiency by dispersing or absorbing energy during laser transmission
Data Source
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AI summary
A joining material for laser welding, a laser welding method using the same, and a laser joined body using the laser welding method. The joining material includes a polymer matrix and a needle-like inorganic filler. The polymer matrix includes a polypropylene resin having a melt index of 80 g/10 min or more to 95 g/10 min or less as measured at a temperature of 230°C and a load of 2.16 kg, and the needle-like organic filler has an aspect ratio of 10:1 to 20:1.