Synthetic Polyisoprene Latex Processing at Low Temperatures
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Solution Overview
Problem
Existing synthetic polyisoprene latex processes result in condoms with inadequate tensile strength and stability due to prevulcanisation, leading to mechanical deficiencies and rapid degradation, while conventional methods fail to maintain physical properties upon ageing.
Innovation Solution
A process involving the compounding and maturation of synthetic polyisoprene latex at temperatures below 17°C to minimize prevulcanisation, ensuring low crosslink density and maintaining the latex at low temperatures throughout preparation and storage to prevent further vulcanisation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If synthetic polyisoprene latex is compounded and matured at conventional temperatures (above 17°C), then the latex undergoes prevulcanisation which increases crosslink density, but this results in condoms with inadequate tensile strength and mechanical deficiencies
Solution Approach 1:
The patent applies parameter changes by controlling the temperature parameter during compounding and maturation to be below 17°C. This temperature control prevents unwanted prevulcanisation and crosslinking reactions, allowing the latex to maintain low crosslink density while achieving superior tensile strength properties in the final condom product.
2Loss of time
If the latex is stored at higher temperatures, then the processing time is reduced, but the latex degrades and loses its mechanical properties
Solution Approach 1:
The patent changes the temperature parameter to below 17°C during storage and processing. This lower temperature parameter slows down degradation reactions and prevulcanisation, allowing the latex to maintain its mechanical properties and reliability throughout the processing timeline, even though it may extend the processing time slightly.
3Ease of manufacture
If conventional curing methods are used, then the latex can be cured, but the condoms exhibit mud cracking and non-uniform thickness
Solution Approach 1:
The patent applies preliminary action by controlling the maturation process at low temperatures (below 17°C) before the actual curing step. This preliminary low-temperature maturation prevents premature crosslinking and prepares the latex in a controlled manner, ensuring that subsequent curing produces uniform films without defects like mud cracking.
Solution Approach 2:
The patent changes the temperature parameter during maturation to below 17°C, which controls the rate and extent of preliminary crosslinking. This parameter control ensures uniform latex composition before curing, leading to uniform film thickness and absence of manufacturing defects.
4Stability of the object's composition
If the latex is allowed to age at higher temperatures, then the storage stability improves, but the condoms deteriorate in physical properties
Solution Approach 1:
The patent applies parameter changes by storing and maturing the latex at temperatures below 17°C. This low temperature parameter slows down both stabilisation and degradation reactions, allowing the latex to maintain its physical properties and strength throughout storage and ageing, achieving both stability and property retention.
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 condoms exhibit superior tensile properties, burst characteristics, and stability, with improved resistance to ageing and minimal film defects, such as 'mud cracking', and uniform thickness.
Implementation Method 1
curing a synthetic polyisoprene rubber latex to form a condom
Implementation Method 2
maintaining the compounded latex at low temperatures throughout the dipping process to minimise further vulcanisation
Data Source
AI summary
The present invention relates to processes for making synthetic polyisoprene latex and synthetic polyisoprene condoms. A process for making a compounded synthetic polyisoprene latex suitable for making a latex film comprises (a) compounding a synthetic polyisoprene latex with suitable compounding ingredients, (b) maturing the latex and optionally (c) storing the latex; characterised in that steps (a), (b) and (c) if included are carried out at a low temperature so as to minimise prevulcanisation of the latex. Condoms can be made from latexes produced according to the process of the invention.