PEDM-Ethylene Copolymer Belt Composition for Green Tack Strength
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Solution Overview
Problem
Existing ethylene-propylene-(diene) polymers (EP(D)M) compositions for transmission belts lack adequate tack and green strength, which are crucial for manufacturing and performance, and current additives like hydrocarbon tackifiers either degrade under heat or increase costs without improving mechanical properties.
Innovation Solution
A composition comprising at least 5 phr of a propylene-α-olefin-diene (PEDM) terpolymer and 20 phr to 95 phr of an ethylene-based copolymer, which enhances green tack, tack aging, and green strength, improving the manufacturing and performance of transmission belts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If polypropylene is used for its chemical resistance and durability, then service life is improved, but impact strength at low temperatures deteriorates
Solution Approach 1:
The patent creates a composite material system consisting of a polypropylene base layer and an elastomeric impact modification layer. The impact modification layer contains an ethylene-based copolymer and a propylene-alpha-olefin-diene composition that are immiscible with each other, forming a two-phase elastomeric system. This composite structure combines the chemical resistance and durability of polypropylene with the low-temperature impact strength of the elastomeric layer, resolving the contradiction between service life and low-temperature impact strength.
2Strength
If impact modification layers are added to improve low-temperature impact strength, then impact strength is improved, but delamination and void formation occur
Solution Approach 1:
The patent applies local quality by creating distinct regions with different properties: the polypropylene base layer provides chemical resistance, while the impact modification layer provides low-temperature impact strength. Within the impact modification layer, two immiscible elastomeric phases are distributed to provide both adhesion to the base layer and impact modification. The specific composition ratios and immiscibility of the elastomeric phases ensure proper adhesion without delamination or void formation, while still providing the required impact strength improvement.
3Strength
If multiple polymers are combined in impact modification layers, then impact strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-formulating the impact modification layer with specific compositions of ethylene-based copolymer and propylene-alpha-olefin-diene composition in predetermined ratios before the actual manufacturing process. The immiscibility of these components is established in advance to ensure proper phase distribution and adhesion properties. This pre-formulation approach simplifies the manufacturing process by reducing the need for complex real-time control of multiple polymer interactions during production, while still achieving the desired impact strength improvement.
Data Source
Figure 1~3
AI summary
An elastomeric composition suitable for use in belts like transmission belts may comprise: from 5 to 100 phr of a propylene-α-olefin-diene (PEDM) terpolymer comprising 80 wt% to 97.5 wt% propylene, 2.5 wt% to 20 wt% a-olefin, and 0.5 wt% to 10 wt% diene, said wt% based on the weight of the PEDM terpolymer, and wherein the PEDM terpolymer has (a) Mooney viscosity (ML(1+4)) of 1 MU to 60 MU, (b) melt flow rate of 0.5 g/min to 100 g/min, and (c) a weight average molecular weight to n-average molecular weight (Mw/Mn) ratio of 1.5 to 3.0; and from 60 to 95 phr of an ethylene-based copolymer comprising 0 wt% to 95 wt% ethylene, 0 wt% to 10 wt% of one or more dienes, and 5 wt% to 60 wt% C3 to C12 α-olefin, said wt% based on the total weight of the ethylene -based copolymer.