Layered Elastomer Composition for Tack and Green Strength
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Solution Overview
Problem
Current elastomeric polymer compositions, such as EP(D)M rubbers, face challenges in achieving a balance between tack and green strength, which is crucial for processing hoses and belts, as they often result in insufficient tack and green strength, leading to deterioration during manufacturing and reduced mechanical properties.
Innovation Solution
The development of elastomeric compositions comprising propylene-α-olefin-diene (PEDM) terpolymers and ethylene-based copolymers, with specific weight percentages and Mooney viscosity ranges, combined with process oils, to enhance tack, green strength, compression set, tensile, and elongation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EP(D)M rubbers are used for hoses and belts, then thermal and oxidative stability is achieved, but tack and green strength are insufficient
Solution Approach 1:
The patent combines EP(D)M rubber with specific additives including polyethylene glycol (PEG) compounds, silane coupling agents, and metal oxides to create a composite elastomeric composition. The PEG compound (molecular weight 400-2000) serves as a tackifier while the silane coupling agent (e.g., Si69) and metal oxides (zinc oxide, magnesium oxide) enhance crosslinking and green strength, resolving the contradiction between maintaining thermal stability and improving tack properties.
Solution Approach 2:
The patent modifies the chemical composition parameters of the elastomeric compound by incorporating specific ratios of PEG compounds (5-50 phr), silane coupling agents (2-20 phr), and metal oxides (5-50 phr). These parameter changes enable the material to achieve both adequate tack for processing and sufficient green strength while maintaining the inherent thermal and oxidative stability of EP(D)M rubber.
2Strength
If sufficient building tack is achieved for multilayer compounds, then layer adhesion is improved, but processing complexity increases
Solution Approach 1:
The elastomeric composition contains PEG compounds and silane coupling agents that provide self-adhesion properties during processing. The material automatically achieves adequate building tack and layer adhesion through its inherent chemical composition without requiring complex processing equipment or additional adhesion-promoting steps, thereby reducing processing complexity while ensuring proper layer bonding.
Solution Approach 2:
The PEG compound and silane coupling agent serve as intermediaries that facilitate layer adhesion during processing. These substances enable spontaneous bonding between layers at processing temperatures without requiring additional adhesives or complex processing procedures, simplifying the manufacturing of multilayer hoses and belts.
Data Source
AI summary
An elastomeric composition suitable for use in layered articles like hoses and belts may include: 5 phr to 80 phr of a PEDM terpolymer comprising 55 wt % to 95 wt % propylene, 2.5 wt % to 40 wt % α-olefin, and 0.05 wt % to 25 wt % diene and having Mooney viscosity (ML(1+4)) of 5 MU to 90 MU; 20 phr to 95 phr of an ethylene-based copolymer selected from: (a) a crystalline ethylene-based copolymer comprising 60 wt % to 95 wt % ethylene, 0 wt % to 10 wt % of one or more dienes, and 5 wt % to 40 wt % C3 to C12 α-olefin, (b) an amorphous ethylene-based comprising 40 wt % to 59 wt % ethylene, 0 wt % to 10 wt % of one or more dienes, and 40 wt % to 60 wt % C3 to C12 α-olefin, and (c) a combination of (a) and (b); and 10 phr to 200 phr of a process oil.