Graft-Modified Polypropylene Adhesive Strength
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Solution Overview
Problem
Conventional polypropylene-based resins lack adhesive strength and flexibility, particularly when combined with other materials, and fail to provide adequate flame retardance, gas barrier properties, and thermostability, limiting their application in packaging and automotive industries.
Innovation Solution
A modified polypropylene-based polymer is developed through graft modification of a propylene/α-olefin copolymer with a xylene-soluble portion and an unsaturated carboxylic acid or its derivative, using a dialkyl peroxide as a radical initiator, which enhances adhesive strength and compatibility with various fillers and resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crystalline polypropylene is blended with maleic acid and radical initiator for graft modification, then adhesive strength is improved, but flow property is notably increased and adhesion interface becomes rigid
Solution Approach 1:
The patent applies parameter changes by controlling the graft modification process to achieve optimal balance between adhesive strength and flow properties. Specifically, it controls the molecular weight distribution, grafting degree, and processing temperature to maintain both adhesion and flowability without excessive rigidity
Solution Approach 2:
The patent uses composite materials by combining polypropylene with specific additives and modifiers that provide both adhesive functionality and flow property control. The composition includes controlled amounts of graft modified polypropylene, lubricants, and process aids to achieve the desired balance
2Ease of operation
If ethylene/α-olefin copolymer rubber is modified with unsaturated carboxylic acids to provide flexibility, then adhesive flexibility is improved, but heat resistance and compatibility with PP are insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition and molecular structure of the polymer to achieve both flexibility and heat resistance. It controls the degree of modification, molecular weight distribution, and crystallinity to balance these opposing requirements
Solution Approach 2:
The patent uses composite materials by creating a blended system that combines the flexibility of modified rubber with the heat resistance of polypropylene. The composition includes specific ratios of rubber, polypropylene, and compatibilizers to achieve synergistic effects
3Strength
If PP and rubber blends are modified with maleic acid to improve adhesion, then adhesive force is enhanced, but tensile strength is inadequate due to lack of dispersibility
Solution Approach 1:
The patent uses an intermediary substance (compatibilizer) that facilitates the dispersion and bonding between polypropylene and rubber phases. This intermediary improves interfacial adhesion and ensures uniform distribution of fillers and reinforcements throughout the composite matrix
Solution Approach 2:
The patent employs composite materials with controlled phase morphology and interfacial bonding. The composition includes specific ratios of polypropylene, rubber, and compatibilizers to achieve optimal dispersibility and mechanical strength
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 modified polymer exhibits excellent adhesive strength, tensile elongation, and abrasion resistance, making it suitable for use as an adhesive or compatibilizer in packaging, automotive, and electrical applications while providing improved flame retardance and mechanical properties.
Implementation Method 1
obtained by graft modification of a propylene/α-olefin copolymer with a xylene-soluble portion of at least 40 mass % and no greater than 85 mass %
Implementation Method 2
using an unsaturated carboxylic acid or its derivative
Implementation Method 3
exhibits excellent adhesive strength and resin improvement as well as a notable effect as a compatibilizer
Implementation Method 4
a dialkyl peroxide with a half-life temperature of at least 170° C. is used as the radical initiator for graft modification
Data Source
AI summary
A modified polypropylene-based polymer obtained by graft modification of a propylene/α-olefin copolymer with a xylene-soluble portion of at least 40 mass % and no greater than 85 mass %, a xylene-soluble portion (XS) intrinsic viscosity (XSIV) of at least 2.5 dl/g, and an MFR value of no greater than 3.0 g/10 min at 230° C. under a load of 2.16 kg, using an unsaturated carboxylic acid or its derivative, and a flame retardant polyolefin-based resin composition having prescribed contents of a polyolefin-based resin component comprising 60-95 mass % of a polyolefin-based resin and 40-5 mass % of a modified polypropylene-based polymer, and an inorganic flame retardant component comprising an inorganic filler.