Metallocene Polyolefin Hotmelt Adhesive for Bond Strength
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Solution Overview
Problem
Existing hotmelt adhesives require compounding of individual components, which is energy-intensive and complex, and they often suffer from impaired bond strength when waxes exceed 10 wt%, leading to diminished properties.
Innovation Solution
A ready-to-use hotmelt adhesive composed of at least 95 wt% polyolefin waxes produced using metallocene catalysts, with specific molar mass and surface tension properties, eliminating the need for further compounding and enhancing cohesion, heat distortion resistance, and low VOC levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If waxes are added to hotmelt adhesives to modify physical properties, then hardness, melt viscosity, and softening point are improved, but bond strength is diminished when wax exceeds 10 wt%
Solution Approach 1:
The patent changes the chemical composition parameters of the wax component by specifying precise propylene content (80-99.9 wt%) and comonomer types (ethylene and/or 1-alkenes with 4-20 carbon atoms). This compositional parameter optimization allows the wax to maintain adequate softening point while improving bond strength performance.
Solution Approach 2:
The patent creates a composite polyolefin wax system combining multiple monomers (propylene as main component with ethylene and/or higher 1-olefins as comonomers) to achieve synergistic effects. This composite structure provides both the desired physical modification properties and improved adhesive performance, resolving the contradiction between softening point and bond strength.
2Ease of manufacture
If polyolefin waxes are used in hotmelt adhesives, then processability and physical property regulation are improved, but manufacturing complexity increases due to compounding requirements
Solution Approach 1:
The patent merges the functions of multiple components (polymer scaffold, resin, and wax modifiers) into a single polyolefin copolymer wax material. This one-component system eliminates the need for separate compounding processes while maintaining all necessary functional properties, thus improving ease of manufacture without increasing manufacturing complexity.
Solution Approach 2:
The polyolefin copolymer wax is designed to perform multiple functions simultaneously: it provides the structural framework, regulates physical properties (hardness, viscosity, softening point), and ensures adequate adhesive performance. This multi-functionality in a single material simplifies the overall manufacturing process.
3Strength
If metallocene-catalyzed polyolefin waxes are used, then cohesion and heat distortion resistance are improved, but open time is reduced
Solution Approach 1:
The patent optimizes the molecular parameters of the polyolefin copolymer wax, specifically controlling the number-average molar mass (15,000-25,000 g/mol) and weight-average molar mass (25,000-35,000 g/mol). This precise molecular weight control balances the competing requirements of high cohesion (requiring higher molecular weight) and adequate open time (requiring lower viscosity from lower molecular weight).
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 solution provides a one-component hotmelt adhesive with improved cohesion, reduced open time, and heat distortion resistance, suitable for bonding low surface energy substrates with a broader application spectrum and lower VOC emissions.
Implementation Method 1
polyolefin waxes produced using metallocene catalysts... produced by direct polymerization of olefins... in which ethylene and/or higher 1-olefins are polymerized at temperatures and pressures which are lower by comparison, with the aid of organometallic catalysts
Implementation Method 2
Hotmelt adhesives or hotmelts are thermoplastic materials which are solid at ambient temperature, and are applied in the liquid-melt state... They are constructed preferably on the basis of resins, waxes, thermoplastic polymers
Data Source
AI summary
The invention relates to a ready-to-use hot melt adhesive containing at least 95% of one or more polyolefin copolymer waxes, which have been prepared by means of metallocene catalysts, characterised in that the polyolefin copolymer wax consists of propylene and one or more further monomers selected from ethylene and branched or unbranched 1-alkenes having 4 to 20 C-atoms and the content of structural units derived from propylene in the copolymer waxes amounts to 80 to 99.9% by weight, and the hot melt adhesive has a surface tension of the melt, measured at a temperature of 170° C., of at most 23 mN/m.