Polyurethane Laminate Coating with Interface Silica Reinforcement
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Solution Overview
Problem
Existing elastomeric laminates, such as condoms, face a challenge in improving tensile strength without significantly increasing the elastic modulus, which can compromise feel and sensitivity.
Innovation Solution
A method involving sequential coating of a substrate with aqueous compositions containing polyurethane and discrete silicon dioxide nanoparticles, allowing the nanoparticles to migrate to the interface between films, thereby reinforcing the laminate without significantly affecting the bulk properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcing agents (silica, carbon black, carbon nanotubes, graphene) are incorporated into elastomeric materials to improve tensile strength, then tensile strength is improved, but elastic modulus increases and elongation to break decreases
Solution Approach 1:
The patent changes the physical state and distribution parameters of silica by using discrete nanoparticles (1-100 nm) instead of conventional reinforcing agents. The nanoparticles are dispersed at low concentrations (0.1-5 wt%) and specifically localized at film interfaces through a multi-layer coating process, transforming how reinforcement is achieved from bulk incorporation to interface-specific placement.
Solution Approach 2:
The patent creates a composite structure by combining polyurethane films with discrete silicon dioxide nanoparticles. The composite is structured as multiple thin films (each containing nanoparticles) rather than a single thick film, with nanoparticles preferentially located at interfaces between films, creating a hierarchical composite architecture that provides reinforcement without excessive stiffness.
2Strength
If reinforcing agents are incorporated to improve tensile strength, then tensile strength is improved, but the material becomes harder and stiffer
Solution Approach 1:
The patent changes the concentration and distribution parameters of reinforcing agents. By using discrete nanoparticles at very low concentrations (0.1-5 wt%) and locating them specifically at film interfaces rather than uniformly throughout the bulk material, the patent achieves tensile strength improvement while minimizing the increase in elastic modulus.
Solution Approach 2:
The patent applies local quality by concentrating reinforcement exactly where it is most needed - at the interfaces between films - rather than uniformly distributing reinforcing agents throughout the entire material. This localized reinforcement at critical stress points provides strength improvement without making the bulk material unnecessarily stiff.
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 method enhances tensile strength of the laminate while maintaining comparable elastic modulus, ensuring improved durability without compromising flexibility and sensitivity.
Implementation Method 1
the incorporation of discrete silicon dioxide nanoparticles into at least the first film-forming composition, which includes a polyurethane, results in a condom having improved tensile strength compared with an equivalent condom lacking the discrete silicon dioxide nanoparticles
Implementation Method 2
coating a substrate with the first aqueous coating composition to form a first film on the substrate
Data Source
AI summary
The present invention relates to a method of preparing an elastomeric laminate article, the method comprising: providing a first aqueous coating composition comprising a first polymer and discrete silicon dioxide nanoparticles, wherein the first polymer is a polyurethane; providing a second aqueous coating composition comprising a second polymer; coating a substrate with the first aqueous coating composition to form a first film on the substrate; coating the first film with the second aqueous coating composition to form a second film on the first film; and removing the substrate. In another aspect, the invention relates to an elastomeric laminate article which comprises a plurality of polymeric films and one or more interfaces, wherein each adjacent pair of films defines one of the interfaces, wherein at least one of the plurality of polymeric films comprises a polyurethane, wherein the laminate comprises silicon dioxide nanoparticles, and wherein at least 60 wt % of the silicon dioxide nanoparticles are present at one or more of the interfaces defined at least in part by a polyurethane-comprising film. In both cases the laminate article may be a condom, and the invention further relates to a condom obtained or obtainable by the inventive method.