Thermoplastic Elastomer Composition Softener Retention
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Solution Overview
Problem
Current thermoplastic elastomer compositions exhibit inferior rubber elasticity, fluidity, adhesion, and softener retention capabilities, particularly when using olefin thermoplastic elastomers that do not require vulcanization, leading to compromised mechanical strength and appearance issues due to mineral oil bleeding.
Innovation Solution
A thermoplastic elastomer composition is developed by dynamically heating a polymer mixture containing an α-olefin thermoplastic resin and an oil-extended ethylene copolymer with specific viscosity and molecular weight ratios, along with mineral oil-based softeners, to achieve enhanced rubber elasticity, fluidity, and softener retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the crosslink density of the ethylene copolymer is increased to improve elastic recovery, then rubber elasticity is improved, but mechanical strength significantly decreases due to decomposition of the α-olefin thermoplastic resin
Solution Approach 1:
The invention changes the molecular weight distribution parameters of the ethylene copolymer, specifically controlling the ratio of weight average molecular weight to number average molecular weight (Mw/Mn) to be 3 or less, and setting the limiting viscosity [η] within 5.5 to 9.0 dl/g. These parameter changes optimize the balance between elastic recovery and mechanical strength without causing resin decomposition
Solution Approach 2:
The invention creates a composite system by combining ethylene copolymer with specific mineral oil-based softeners in a controlled ratio (50 to 150 parts softener per 100 parts ethylene copolymer). This composite structure improves both rubber elasticity and softener retention capability while maintaining mechanical strength
2Productivity
If a large amount of mineral oil-based softener is added to improve fluidity, then fluidity is improved, but mineral oil bleeds out due to insufficient retention capability, deteriorating the appearance
Solution Approach 1:
The invention optimizes the molecular weight distribution parameters of the ethylene copolymer, specifically controlling the ratio of weight average molecular weight to number average molecular weight (Mw/Mn) to be 3 or less, and setting the limiting viscosity within 5.5 to 9.0 dl/g. These parameter changes enhance the polymer's ability to retain mineral oil softeners while maintaining fluidity
Solution Approach 2:
The invention creates a heterogeneous structure where the ethylene copolymer with optimized molecular weight distribution provides localized retention capability for mineral oil softeners. The specific viscosity and molecular weight ratio create regions within the polymer matrix that effectively hold the softener, preventing bleeding while maintaining overall fluidity
3Reliability
If the limiting viscosity and molecular weight ratio of ethylene copolymer are optimized to improve rubber elasticity, then elastic recovery is improved, but dispersion of the components becomes insufficient, reducing mechanical strength
Solution Approach 1:
The invention optimizes the limiting viscosity [η] to be within 5.5 to 9.0 dl/g and the molecular weight ratio (Mw/Mn) to be 3 or less. These parameter changes create an optimal balance where the polymer chains have sufficient entanglement for elastic recovery but remain dispersible throughout the composition
Solution Approach 2:
The invention uses a controlled amount of mineral oil-based softener (50 to 150 parts per 100 parts ethylene copolymer) to achieve sufficient lubrication and dispersion without excessive softening that would compromise mechanical strength. The softener content is optimized to provide just enough separation and distribution of components
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 demonstrates improved rubber elasticity, fluidity, adhesion, and softener retention, maintaining mechanical strength and appearance integrity, making it suitable for various applications such as exterior moldings and seal materials.
Implementation Method 1
an ethylene copolymer that satisfies the conditions (1) and (2)... (1) A limiting viscosity [η] measured at 135° C. in a decalin solvent of 5.5 to 9.0 dl/g... (2) A ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 3 or less
Data Source
AI summary
A thermoplastic elastomer composition that exhibits excellent rubber elasticity, etc. is obtained by dynamically heating a polymer composition in the presence of the crosslinking agent, the polymer composition including an α-olefin thermoplastic resin (A), and an oil-extended ethylene copolymer (B) that includes an ethylene copolymer that satisfies given conditions, and 50 to 150 parts by mass of a first mineral oil-based softener based on 100 parts by mass of the ethylene copolymer, the content of the oil-extended ethylene copolymer (B) being 30 mass % or more based on the total amount (=100 mass %) of the polymer component including the α-olefin thermoplastic resin (A) and the oil-extended ethylene copolymer (B).