Composite Resin Particles for Automotive Trim
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Solution Overview
Problem
Existing composite resin particles and expanded molded articles lack both high impact resistance and high expandability, making them unsuitable for applications requiring both mechanical strength and lightweight properties, such as automotive interior trims.
Innovation Solution
Composite resin particles are developed with a specific sea-island and co-continuous structure by combining polyolefin-based and polystyrene-based resins, where the polystyrene-based resin is dispersed in the polyolefin-based resin with a controlled morphology, and produced through a method involving seed polymerization and specific temperature conditions to achieve both impact resistance and expandability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If polystyrene-based resin is used for expanded molded articles, then expandability and shock-absorbing properties are improved, but impact resistance and plasticity deteriorate
Solution Approach 1:
The invention uses composite resin particles comprising both polyolefin-based resin and polystyrene-based resin. The polyolefin component provides impact resistance and plasticity, while the polystyrene component provides expandability and shock-absorbing properties. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The invention creates a specific internal morphology where polystyrene-based resin particles are dispersed within the polyolefin-based resin matrix in a sea-island structure. This local distribution allows different regions of the material to exhibit different properties: the polystyrene domains provide expandability while the polyolefin matrix provides impact resistance.
2Strength
If polyolefin-based resin is used for expanded molded articles, then impact resistance and plasticity are improved, but expandability deteriorates
Solution Approach 1:
The composite resin particles combine polyolefin-based resin and polystyrene-based resin in specific mass ratios (50-800 parts polystyrene per 100 parts polyolefin). This composite approach allows the material to exhibit both the impact resistance of polyolefin and the expandability of polystyrene simultaneously.
Solution Approach 2:
The invention controls the mass ratio parameters of the composite resin components and the particle size distribution to optimize both impact resistance and expandability. By adjusting these parameters, the material achieves a balance between mechanical strength and expansion capability.
3Duration of action of moving object
If polystyrene-based composite resin particles are used, then expandability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention pre-forms composite resin particles with a specific sea-island internal morphology before the expansion process. The polystyrene-based resin particles are pre-dispersed within the polyolefin-based resin matrix, creating a structure that is ready for expansion. This preliminary structuring simplifies the subsequent expansion process while ensuring consistent expandability.
Solution Approach 2:
The composite resin particles have a nested structure where polystyrene-based resin particles are dispersed within the polyolefin-based resin matrix. This sea-island structure allows the smaller polystyrene particles to be contained within the larger composite particle structure, simplifying handling and processing while maintaining the desired expandability.
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 resulting composite resin particles and expanded molded articles exhibit enhanced impact resistance and expandability, enabling their use in applications like automotive interior trims that require both mechanical strength and lightweight properties.
Implementation Method 1
carrying out first polymerization of the styrene-based monomer at a temperature of T2 to (T2 + 35)°C
Implementation Method 2
heating the resulting dispersion at a temperature at which the styrene-based monomer does not substantially polymerize and immersing the styrene-based monomer in the particles of the polyolefin-based resin
Implementation Method 3
particles of a polyolefin-based resin having at least two melting peaks in a differential scanning calorimetry (DSC) curve obtained by DSC
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)~3(c)
AI summary
Composite resin particles comprising 50 to 800 parts by mass of a polystyrene-based resin with respect to 100 parts by mass of a polyolefin-based resin, wherein: when transmission electron microscope (TEM) images obtained by photographing cross-sections of the composite resin particles using a TEM at a magnification of 1,000 are subjected to a binarization processing and areas in the obtained binarized images which correspond to a cross-sectional area of 437.584 µm2 of the composite resin particles are subjected to image analysis, the polystyrene-based resin satisfies the following requirements: (1) the number of dispersed particles is 180 or more; (2) the maximum of the areas of dispersed particles is 200 µm2 or less; and (3) the coefficient of variation in dispersion is 100% or more, and the composite resin particles exhibit an inner morphology that includes a mixture of sea-island structure regions in which particles of the polystyrene-based resin are dispersed in the polyolefin-based resin and co-continuous structure regions in which particles of the polystyrene-based resin having an indefinite shape is dispersed in the polyolefin-based resin.