Cyclic Olefin Polyolefin Elastomer for Low-Leaching Adhesives
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Solution Overview
Problem
Conventional polyolefin elastomers in adhesive compositions require a large amount of tackifier to achieve a desirable glass transition temperature (Tg), leading to tackifier leaching issues in hygiene and packaging applications.
Innovation Solution
A polyolefin elastomer composed of 50 mol% to 99.5 mol% ethylene, 0.5 mol% to 30 mol% C3-C14 α-olefin, and 0.5 mol% to 20 mol% cyclic olefin, with a tailored Tg of -50 °C to 30 °C and a weight average molecular weight (Mw) of 5,000 g/mol to 150,000 g/mol, is used to enhance peel strength without the need for excessive tackifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a relatively large amount of tackifier is added to increase Tg, then the glass transition temperature is improved, but tackifier leaching occurs
Solution Approach 1:
The invention changes the chemical composition parameters of the polyolefin elastomer by incorporating cyclic olefin units (0.5-20 mol%) alongside ethylene and alpha-olefin. This compositional parameter change directly modifies the Tg of the elastomer itself, eliminating the need to add external tackifiers to achieve the desired temperature range, thereby preventing tackifier leaching
Solution Approach 2:
The invention creates a composite polyolefin elastomer structure combining three different monomer types (ethylene, alpha-olefin, and cyclic olefin) with specific molar ratios. This composite material approach allows tailoring of the Tg through the synergistic interaction of different polymer segments, achieving the desired thermal properties without external additives
2Strength
If the Tg is increased closer to end-use temperature, then peel strength is improved, but the amount of tackifier required increases
Solution Approach 1:
The polyolefin elastomer serves its own function of achieving the desired Tg through its inherent compositional design. The cyclic olefin-containing elastomer self-adjusts its glass transition temperature to match end-use conditions without requiring external tackifier substances, making the system self-sufficient
Data Source
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AI summary
Embodiments are directed to a polyolefin elastomer comprising a polymerized reaction product of 50 mol% to 99.5 mol% ethylene, 0.5 mol% to 30 mol% C3-C14 α-olefin, and 0.5 mol% to 20 mol% cyclic olefin. The polyolefin elastomer comprises a glass transition temperature of -50 °C to 30 °C, as measured according to Differential Scanning Calorimetry and a weight average molecular weight of 5,000 g/mol to 150,000 g/mol, as measured according to conventional Gel Permeation Chromatography. Further embodiments are directed to adhesive compositions comprising the polyolefin elastomer.