Structure Adhesive Composition for Stitch Coating and Shower Resistance
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Solution Overview
Problem
Existing structure adhesive compositions for vehicle body panels have low shower resistance and exhibit stringiness during stitch-coating, leading to poor adhesion and anticorrosive properties.
Innovation Solution
A structure adhesive composition containing dispersed rubber particles in an epoxy resin with a latent curing agent, without liquid rubber, offering a viscosity range suitable for stitch-coating and improved shower resistance, used in a weld-bonding technique.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the viscosity at 40°C is kept low (around 200 Pa·s) for easy coating, then the adhesive can be easily applied, but shower resistance becomes low and the adhesive may be blown away by shower
Solution Approach 1:
The patent changes the temperature parameter for viscosity measurement from 40°C to 50°C, and specifies a viscosity range of 190-380 Pa·s at the higher temperature. This parameter change allows the adhesive to maintain appropriate viscosity for coating at application temperature while developing sufficient shower resistance as it cools and cures.
Solution Approach 2:
The patent uses a composite adhesive formulation containing rubber particles dispersed in epoxy resin, combined with a latent curing agent. This composite structure provides both the necessary workability during application and the required shower resistance after curing, resolving the contradiction between ease of coating and shower resistance.
2Strength
If liquid rubber component is used to improve adhesion, then bonding strength is enhanced, but the adhesive stretches out like a string during stitch-coating and attaches to unintended places
Solution Approach 1:
The patent extracts and eliminates the liquid rubber component from the adhesive formulation, replacing it with rubber particles dispersed in epoxy resin. This removal of the problematic liquid rubber eliminates the stringing issue during stitch-coating while maintaining adhesion strength through the alternative rubber particle reinforcement mechanism.
Solution Approach 2:
The patent changes the physical state of the rubber component from liquid to particulate form, with rubber particles having a specific size distribution (0.01-10 μm). This parameter change in the rubber component's physical state prevents the adhesive from stretching into strings during stitch-coating while still providing adhesion enhancement.
3Area of stationary object
If the adhesive is stretched out like a string during stitch-coating, then coating coverage increases, but the adhesive attaches to unintended places and adversely affects electrodeposition coating
Solution Approach 1:
By removing the liquid rubber component that causes excessive stretching and stringing, the patent prevents the adhesive from attaching to unintended areas. This extraction of the problematic component maintains adequate coating coverage through proper application while eliminating placement accuracy issues.
Solution Approach 2:
The patent changes the rheological parameters of the adhesive by using rubber particles instead of liquid rubber, and by specifying viscosity at 50°C rather than 40°C. These parameter changes control the adhesive's flow behavior during stitch-coating, preventing excessive stretching while ensuring adequate coverage.
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 adhesive composition provides favorable thread breakage, enhanced shower resistance, and prevents stringiness, enabling effective adhesion and improved workability in vehicle production lines.
Implementation Method 1
an epoxy resin in which rubber particles are dispersed as primary particles
Implementation Method 2
an epoxy resin latent curing agent
Data Source
AI summary
Provided are: a structure adhesive composition which exhibits favorable thread breakage and improves shower resistance, and prevents stringiness when stitch-coating is performed; a method for producing a vehicle structure using the same; and a vehicle structure. A structure adhesive composition exhibiting favorable thread breakage, the structure adhesive composition being a structure adhesive composition containing no liquid rubber component,the structure adhesive composition contains:(A) an epoxy resin in which rubber particles are dispersed as primary particles; and(B) an epoxy resin latent curing agent;a compounded proportion of the rubber particles in the structure adhesive composition is from 10 to 45 mass %; anda viscosity at 50° C. of the structure adhesive composition is from 190 to 380 (Pa·s) when a shearing speed is 5 (sec−1) and is from 1 to 30 (Pa·s) when the shearing speed is 200 (sec−1).