Polyolefin Membrane Adhesion Without Bonding Agents
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Solution Overview
Problem
Existing polyolefin membranes for waterproofing applications, such as roofing and geomembranes, lack sufficient chemical inertness, tensile strength, tear and puncture resistance, and UV resistance, while also experiencing surface stickiness and inadequate adhesion for metal layers and inks.
Innovation Solution
A multilayer membrane structure comprising a base layer (A) with a heterophasic composition of propylene and ethylene copolymers, and a top layer (B) of ethylene homopolymer or copolymer, where the top layer is at least partially bonded to the base layer without a bonding agent, enhancing mechanical properties and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a thin layer of material with special properties is coupled on top of a layer of standard base material to achieve fire retardancy and UV resistance, then surface protection properties are improved, but surface stickiness increases and adhesion for metal layers and inks deteriorates
Solution Approach 1:
The patent applies local quality by creating a multilayer structure where each layer has specific properties: the top layer (B) provides UV resistance and fire retardancy, while the base layer (A) with propylene polymers provides low stickiness and good adhesion. This resolves the contradiction by localizing the protective function to the top layer while maintaining the base layer's adhesion properties.
Solution Approach 2:
The patent uses composite materials by combining propylene polymers (for low stickiness and adhesion) with ethylene copolymers (for UV resistance and fire retardancy) in a multilayer structure. This composite approach allows simultaneous achievement of surface protection and adhesion properties that single materials cannot provide.
2Strength
If standard base material is used to ensure mechanical properties, then tensile strength is maintained, but chemical inertness and tear resistance are insufficient
Solution Approach 1:
The patent employs composite materials by formulating the base layer with specific propylene polymer compositions (homopolymers and copolymers with controlled xylene insolubility) that provide both mechanical strength and chemical inertness. The heterophasic composition creates a material that simultaneously achieves tensile strength and resistance to chemical degradation.
3Strength
If bonding agents are used between layers to ensure adhesion, then interlayer bonding is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies self-service by designing the multilayer structure to bond without external bonding agents. The specific polymer compositions in layers (A) and (B) are selected to provide inherent bonding capability through their chemical and physical properties, eliminating the need for additional bonding agents and simplifying the manufacturing process.
Solution Approach 2:
The patent uses parameter changes by controlling the chemical composition and physical properties of the polymer layers (molecular weight, composition ratios, crystallinity) to optimize interlayer adhesion. By adjusting these parameters, the layers achieve sufficient bonding without requiring external bonding agents.
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 membrane achieves high chemical inertness, improved tensile and puncture resistance, reduced surface stickiness, excellent scratch and UV resistance, and optimal adhesion for metal layers and inks, with superior mechanical properties and thermal weldability.
Implementation Method 1
the layer (B) being at least partially bonded to the layer (A)... Preferably the layer (B) is at least partially bonded to the layer (A) in the absence of a bonding agent (like a hot melt adhesive) between the two layers
Data Source
AI summary
A membrane comprising a layer (A) and a layer (B), where the layer (A) comprises a composition (i) containing the following polymer components, all percent amounts being by weight: a) 10-40% of a propylene homopolymer and/or or copolymer containing over 85% of propylene, and having a fraction insoluble in xylene at room temperature greater than 80%; and b) 60-90% of one or more α-olefin/ethylene copolymers containing less than 40% of ethylene and having solubility in xylene at room temperature greater than 70%; the amounts of (a) and (b) being referred to the total weight of (a) and (b); and the layer (B) comprises an ethylene homopolymer and/or copolymer having density from 0.915 to 0.980 cm3/g; said layer (B) being at least partially bonded to the layer (A).