Propane Flame Activation for Plastic Bonded Structures
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Solution Overview
Problem
Existing methods for bonding polymeric materials face challenges due to the inherent incompatibility of the materials, leading to difficulties in achieving strong adhesion, and there is a need for an improved method to activate the bonding surfaces effectively.
Innovation Solution
A process involving the treatment of plastic parts with a flame of a propane-comprising gas mixture, followed by application of a bonding agent and optionally a primer, to enhance the surface energy and adhesion properties, suitable for preparing automotive parts such as tailgates, roof spoilers, and instrument panel carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bonding agent is applied to polymeric material surfaces, then bonding is achieved, but adhesion is difficult due to chemical incompatibility between the bonding agent and polymeric material
Solution Approach 1:
The patent applies preliminary surface activation treatments (flame treatment, plasma treatment, corona treatment, or chemical etching) to the polymeric material surfaces before applying the bonding agent. This preliminary action modifies the surface chemistry and topology to create sites that are chemically compatible with the bonding agent, thereby enabling strong adhesion without requiring complex bonding agents or primers.
Solution Approach 2:
The patent changes the surface parameters of the polymeric material through activation treatments. Flame treatment introduces oxygen-containing functional groups and increases surface energy, while plasma and corona treatments modify surface chemistry by introducing polar groups. These parameter changes make the surface more receptive to the bonding agent, resolving the chemical incompatibility issue.
2Strength
If surface activation is performed to enhance adhesion, then bonding strength is improved, but process complexity increases
Solution Approach 1:
The patent replaces complex mechanical or chemical surface preparation systems with simpler thermal-field-based activation methods. Flame treatment uses a controlled flame to activate surfaces rapidly, while plasma and corona treatments use electrical discharges in gas environments. These substitutions achieve surface activation without requiring mechanical abrasion equipment or complex chemical etching facilities, thereby reducing overall process complexity.
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 significantly improves the adhesion strength and reduces adhesion failure, enabling the production of high-quality bonded structures suitable for automotive applications by increasing the surface energy and wettability of the plastic parts.
Implementation Method 1
treating at least part of a first bonding surface of said first plastic part with a flame of a propane-comprising gas
Implementation Method 2
during treatment with a flame of the propane-comprising gas, a flame is produced by burning a mixture of air and the propane-comprising gas
Data Source
AI summary
The invention relates a process for the preparation of a bonded structure (4) comprising at least a first plastic part (1) having a first bonding surface (1a), said process comprising the step of a) treating at least part of a first bonding surface of said first plastic part with a flame of a propane-comprising gas, said propane-comprising gas being propane or a mixture comprising at least 50 wt. % of propane based on the weight of the propane-comprising gas with one or more gases selected from the group consisting of methane, ethane, butane, pentane, and hexane, wherein, during treatment with a flame of the propane-comprising gas, a flame is produced by burning a mixture of air and the propane-comprising gas, wherein the gas-to-air ratio is chosen such that the propane gas to oxygen volume ratio is equal to or less than 1:5.01, for example less than 1:5.00 and preferably at least 3.50 to obtain a first plastic part having a flame-treated first bonding surface.