Unsaturated Polyester Battery Pack Housing With Low Shrinkage
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Solution Overview
Problem
Molded articles made from unsaturated polyester resin compositions exhibit poor dimensional stability when combined with light metals due to differences in linear expansion coefficients, leading to issues such as warping and deformation, and require improved flame retardancy and low shrinkage.
Innovation Solution
An unsaturated polyester resin composition containing specific ratios of polybasic acid, polyhydric alcohol, polyvinyl acetate, aluminum hydroxide, and a fire retardant, along with a reinforced fiber, to achieve low shrinkage, flame retardancy, and dimensional stability when integrated with light metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional unsaturated polyester resin composition is used, then the molded article has good mechanical properties and water resistance, but poor dimensional stability when combined with light metal due to linear expansion coefficient difference
Solution Approach 1:
The patent modifies the chemical composition parameters of the unsaturated polyester resin by incorporating specific ratios of polybasic acid (80 mol% or more), polyhydric alcohol, and additives like aluminum hydroxide (50-150 parts by mass) and fire retardants. These parameter changes adjust the linear expansion coefficient of the cured resin to match that of light metals, thereby improving dimensional stability when combined with aluminum alloy components.
Solution Approach 2:
The patent creates a composite resin system by combining unsaturated polyester with multiple functional components including aluminum hydroxide, fire retardants, and specific polybasic acids. This composite approach allows simultaneous achievement of matched linear expansion coefficient, flame retardancy, and mechanical properties, resolving the dimensional stability issue when paired with light metal structures.
2Weight of moving object
If the molded article is designed for lightweight application, then weight reduction is achieved, but flame retardancy and low shrinkage properties are insufficient
Solution Approach 1:
The patent incorporates aluminum hydroxide (50-150 parts by mass) which serves dual functions: it acts as a flame retardant that releases water upon heating to suppress combustion, and simultaneously functions as a filler that maintains the lightweight characteristic. This converts the potential harm of added filler weight into a benefit by achieving flame retardancy while keeping the overall structure lightweight compared to traditional metal components.
Solution Approach 2:
The resin composition is formulated with specific parameter ranges including polybasic acid content (80 mol% or more), aluminum hydroxide (50-150 parts by mass), and fire retardant (15-70 parts by mass relative to aluminum hydroxide). These parameter optimizations ensure the cured resin achieves both low shrinkage during curing and superior flame retardancy, meeting safety requirements for lightweight vehicle components.
3Object-affected harmful factors
If aluminum hydroxide is increased to improve flame retardancy, then flame retardancy is enhanced, but the linear expansion coefficient difference with light metal increases
Solution Approach 1:
The patent defines a precise parameter range for aluminum hydroxide content (50-150 parts by mass per 100 parts by mass of resin component) and fire retardant content (15-70 parts by mass per 100 parts by mass of aluminum hydroxide). Within this optimized range, the composition achieves a balance where flame retardancy is sufficiently enhanced while the linear expansion coefficient remains matched to light metals, preventing dimensional instability.
Solution Approach 2:
The patent creates a balanced composite formulation combining aluminum hydroxide with specific ratios of polybasic acid (80 mol% or more), polyhydric alcohol, and fire retardants. This composite approach ensures that the flame retardant properties are optimized while the overall linear expansion coefficient of the cured resin remains compatible with aluminum alloy components, simultaneously achieving both flame retardancy and dimensional stability.
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 composition results in molded articles with excellent low shrinkage, flame retardancy, and dimensional stability, making them suitable for battery pack housings in electric vehicles.
Implementation Method 1
aluminum hydroxide is blended in an amount of 50 parts by mass or more and less than 150 parts by mass relative to 100 parts by mass of the resin component
Implementation Method 2
an unsaturated polyester resin composition including: a resin component containing an unsaturated polyester, a polymerizable monomer
Implementation Method 3
the low profile agent contains polyvinyl acetate, the polyvinyl acetate is blended in an amount of 3 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the resin component
Data Source
AI summary
An unsaturated polyester resin composition includes: a resin component comprising an unsaturated polyester, a polymerizable monomer, and a low profile agent; aluminum hydroxide; and a fire retardant. The unsaturated polyester is a polymerized product of polybasic acid and polyhydric alcohol. The polybasic acid has an ethylenic unsaturated double bond at a predetermined ratio. The polyvinyl acetate is blended as a low profile agent relative to the resin component at a predetermined ratio. Aluminum hydroxide is blended relative to the resin component at a predetermined ratio.