Foam Molding Masterbatch With Microcapsules for High-Shear Expansion
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Solution Overview
Problem
Existing masterbatches for foam molding face challenges in handling chemical foaming agents that decompose under heat, leading to residue and open cells, and thermally expandable microcapsules provide low expansion ratios and poor appearance quality, especially in high shear force or low temperature molding processes.
Innovation Solution
A masterbatch containing an olefin elastomer as the base resin and a thermally expandable microcapsule, with specific gravity of 0.80 g/cm3 or more, in the range of 40 to 300 parts by weight relative to the base resin, optimized to achieve high expansion ratios and good appearance quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a chemical foaming agent is used in the masterbatch, then the foam molded article can achieve high expansion ratio, but the foaming agent rapidly decomposes under heat and produces residue that affects adhesiveness and creates open cells
Solution Approach 1:
The patent changes the physical state parameter of the foaming agent from chemical decomposition (chemical foaming agent) to thermal expansion (thermally expandable microcapsule). This parameter change allows the system to achieve expansion without rapid chemical decomposition, eliminating residue formation and open cell defects while maintaining high expansion ratio.
Solution Approach 2:
The patent replaces the reusable chemical foaming agent with disposable thermally expandable microcapsules that expand once upon heating and then remain stable. These microcapsules are designed to be consumed in a controlled manner during the foaming process, providing reliable expansion without the harmful side effects of chemical decomposition.
2Reliability
If a thermally expandable microcapsule is used as foaming agent, then residue and open cells are eliminated, but the expansion ratio is low and cells cannot be adjusted to predetermined size
Solution Approach 1:
The patent creates a composite system combining thermally expandable microcapsules with specifically selected base resins (polyolefin, styrene resin, or olefin elastomer) and control agents. This composite material approach allows the microcapsules to achieve higher expansion ratios while maintaining their reliability advantages, as the matrix resin and control agents work synergistically to enhance overall foam expansion and cell structure control.
Solution Approach 2:
The patent applies local quality control by selecting different base resin types (polyolefin, styrene resin, olefin elastomer) with specific properties to work with the thermally expandable microcapsules in different regions or applications. This allows optimization of expansion ratio and cell size for specific molding conditions while maintaining the fundamental advantages of thermally expandable microcapsules.
3Ease of operation
If the base resin has high miscibility with thermally expandable microcapsule, then processing is improved, but the shell of microcapsule may break under high shear force
Solution Approach 1:
The patent carefully controls the molecular weight and composition parameters of the base resin to achieve optimal balance between miscibility and shear resistance. By adjusting these parameters, the system attains sufficient miscibility for good processing while maintaining adequate shear strength to protect microcapsule shells during high shear force molding operations.
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 masterbatch enables stable foam molding with high expansion ratios and improved appearance quality, even under high shear force or low temperature conditions, by using a thermally expandable microcapsule with a shell composed of a monomer mixture that enhances gas barrier properties and heat resistance.
Implementation Method 1
a thermally expandable microcapsule... the shell of which contains a polymer obtained by polymerizing a monomer mixture
Implementation Method 2
the shell of which contains a polymer obtained by polymerizing a monomer mixture that contains a polymerizable monomer (I) containing at least one selected from acrylonitrile, methacrylonitrile, and vinylidene chloride
Data Source
AI summary
The present invention aims to provide a masterbatch for foam molding which can be suitably used in molding involving high shear force or molding requiring low molding temperature and which can provide a foam molded article having a high expansion ratio and good appearance quality. The present invention also aims to provide a foam molded article formed from the masterbatch for foam molding. Provided is a masterbatch for foam molding, containing: a base resin; and a thermally expandable microcapsule, the masterbatch having a true specific gravity of 0.80 g/cm3 or more, the base resin containing an olefin elastomer, the masterbatch containing the thermally expandable microcapsule in an amount of 40 to 300 parts by weight relative to 100 parts by weight of the base resin.