Nitrile Rubber Condoms Softness via Crosslinking
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Solution Overview
Problem
Nitrile rubber articles, such as surgical gloves and condoms, are traditionally stiffer than those made from natural rubber latex, making them less comfortable to wear, despite offering improved chemical resistance and allergy safety.
Innovation Solution
A compounded nitrile rubber formulation comprising nitrile latex, a crosslinking agent, a metal oxide, a vulcanization accelerator, an antioxidant, an alkali agent, and a heat sensitizer is used to create flexible elastomeric films with improved softness and strength, achieved through specific weight percentages and crosslinking mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitrile rubber is used instead of natural rubber latex, then chemical resistance and allergy safety are improved, but the article becomes stiffer and less comfortable to wear
Solution Approach 1:
The patent modifies the physical and chemical parameters of nitrile rubber by controlling the acrylonitrile content (18-42 parts per 100 parts rubber) and using specific curing agents (zinc oxide at 1-10 parts per 100 parts rubber) to adjust the polymer's flexibility and softness, transforming nitrile rubber from a stiff material to one that is soft and comfortable while maintaining chemical resistance
Solution Approach 2:
The patent creates a composite formulation by combining nitrile rubber with specific additives including zinc oxide, sulfur, accelerators, and other curing agents in precise proportions, where the interaction between these components produces a material that achieves both chemical resistance and flexibility that neither component could provide alone
2Strength
If nitrile rubber is used instead of natural rubber latex, then puncture resistance is improved, but the article becomes stiffer and harder to stretch
Solution Approach 1:
The patent adjusts the polymer composition parameters by controlling acrylonitrile content and using specific curing systems to modify the rubber's mechanical properties, achieving a balance where the material maintains high puncture resistance while becoming sufficiently flexible and easy to stretch for medical applications
3Reliability
If acrylonitrile level is increased, then resistance to aliphatic oils and solvents is improved, but the polymer becomes stiffer
Solution Approach 1:
The patent optimizes the acrylonitrile content within a specific range (18-42 parts per 100 parts rubber) rather than using high levels, and compensates by adjusting curing agent proportions to achieve the desired balance between chemical resistance and flexibility, preventing excessive stiffness while maintaining solvent resistance
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 resulting elastomeric articles exhibit superior elongation, tactility, and chemical resistance while maintaining mechanical strength, providing a comfortable and effective barrier for medical applications.
Implementation Method 1
Crosslinking also increases the strength and elasticity of the rubber. Carboxylated nitrile latexes can be chemically crosslinked in at least two ways: the butadiene subunits can be covalently crosslinked with sulfur/accelerator systems; and the carboxylated (organic acid) sites can be ionically crosslinked with metal oxides or salts.
Implementation Method 2
the carboxylated (organic acid) sites can be ionically crosslinked with metal oxides or salts
Implementation Method 3
the butadiene subunits can be covalently crosslinked with sulfur/accelerator systems; Sulfur crosslinks often result in large improvements in oil and chemical resistance
Implementation Method 4
By dipping suitable molds into a bath of this formulation, and curing the nitrile rubber before removing it from the mold
Data Source
AI summary
This invention provides a method of making an elastomeric article, and the method comprises dipping a mold into a first dip tank containing a compounded nitrile rubber formulation to produce an elastomeric film layer on the mold, the compounded nitrile rubber formulation comprising nitrile butadiene copolymer; a crosslinking agent; a metal oxide; a vulcanization accelerator; an antioxidant; an alkali agent; and a heat sensitizer; then drying and curing the elastomeric film layer to form the elastomeric article. The heat sensitizer may be an organopolysiloxane. Elastomeric articles prepared according to this invention may have a film thickness in a range of 0.020 mm to 0.050 mm; such films are suitable for medical examination gloves, surgical gloves, or condoms.