Metallocene Polyolefin Contact Adhesives Without Mineral Oils
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Solution Overview
Problem
There is a need for effective hot-melt adhesives that can be formulated without the addition of mineral oil products, as mineral oils are considered toxicologically risky and undesirable, particularly in applications such as food packaging.
Innovation Solution
The use of polyolefins produced with metallocene catalysts, specifically copolymers of propylene with ethylene and/or higher 1-olefins, which have a pour point of <50 °C, viscosity between 20 and 3000 mPa.s at 170 °C, and a glass transition temperature of <-35 °C, allowing them to function as both base polymers and plasticizers in pressure-sensitive adhesives, eliminating the need for mineral oils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mineral oils are added to pressure-sensitive adhesives to improve cohesion and adhesive properties, then the bonding performance is enhanced, but the toxicological safety is compromised due to potential accumulation in human tissue
Solution Approach 1:
The patent removes mineral oils from the adhesive formulation entirely, extracting the harmful component while maintaining bonding performance through alternative polyolefin-based plasticizers that are non-toxic and do not accumulate in human tissue
Solution Approach 2:
The patent changes the chemical composition parameters by replacing mineral oil hydrocarbons with specific polyolefin copolymers (ethylene-propylene-diene-monomer or ethylene-1-butene copolymers) having controlled molecular weight and composition, thereby altering the adhesive's chemical properties to eliminate toxicity while preserving mechanical bonding characteristics
2Device complexity
If conventional polyolefins produced with Ziegler-Natta catalysts are used in pressure-sensitive adhesives, then the formulation is simpler, but the adhesive properties and cohesion are insufficient without requiring mineral oil additives
Solution Approach 1:
The patent changes the catalyst type parameter from Ziegler-Natta to metallocene catalysts, which produces polyolefins with superior molecular weight distribution and microstructure, enabling the material to achieve adequate adhesive properties without mineral oil additives
Solution Approach 2:
The patent creates a composite adhesive system combining polyolefin base polymer with specific plasticizers and resin components, where the metallocene-produced polyolefin provides enhanced cohesion that works synergistically with other adhesive components to achieve overall bonding performance without harmful additives
3Strength
If polyolefins with specific metallocene-produced microstructure are used, then the adhesive performance without mineral oils is achieved, but the manufacturing process becomes more complex due to specific catalyst requirements
Solution Approach 1:
The patent specifies precise parameter ranges for the metallocene catalyst system, including catalyst type, co-catalyst composition, and polymerization conditions (temperature, pressure, monomer ratios), which standardize the manufacturing process and enable consistent production of high-performance adhesive polyolefins
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
These metallocene-produced polyolefins provide a suitable alternative for pressure-sensitive adhesives, offering improved cohesion and adhesive properties without the use of mineral oils, ensuring safer and more reliable bonding in various applications.
Implementation Method 1
copolymers of propylene with ethylene and/or with higher 1-olefins C4-C20, the copolymers being produced using metallocene catalysts
Implementation Method 2
Pressure sensitive adhesives (PSA) form viscoelastic films between the parts to be bonded. The adhesive bond, which is based on purely physical principles
Implementation Method 3
glass transition temperatures between -15 and +10 °C
Data Source
AI summary
The invention relates to contact adhesive compounds containing 5 to 50 wt% copolymers of propylene having ethylene and/or having olefins, selected from the group of 1-olefins having 4 to 20 C atoms, wherein the copolymers have been produced with the aid of metallocene catalysts and are characterized by a) a flow point, measured in accordance with ASTM D97, of < 50 °C, b) a viscosity at 170 °C in the range from 20 to 3000 mPa.s, measured with a rotary viscometer to DIN 53019, c) a density in the range from 0.84 to 0.90 g/cm3, measured at 23 °C in accordance with ISO 1183, d) a glass transition temperature of < -35 °C, measured in accordance with the DSC method according to DIN EN ISO 11357-2:2014.