Continuous Elastomeric Film Casting with Reversible Crosslinking
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Solution Overview
Problem
The existing dip-molding technology for producing elastomeric films, such as examination gloves, results in high water waste, energy consumption, and space occupation, and requires a stable water supply, while using materials that need to be thermoplastic for sealing.
Innovation Solution
A method involving the production of a continuous elastomeric film using an aqueous polymer latex composition with thermally reversible linkages formed from latex polymer particles and a crosslinking component, allowing for the formation of a continuous polymer film that can be cured and rolled, eliminating the need for sulfur vulcanization and reducing waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If dip-molding process is used to produce elastomeric films, then mechanical strength can be achieved through crosslinking, but large amounts of waste water are produced and energy consumption is high
Solution Approach 1:
The patent changes the crosslinking mechanism from sulfur-based vulcanization to carbonyl chemistry. The new system uses carbonyl groups (from compounds like itaconic acid or maleic acid) that react with diamine crosslinking agents to form beta-amino carbonyl linkages. This chemical parameter change eliminates the need for sulfur, accelerators, and zinc oxide, thereby reducing waste water and energy consumption associated with traditional dip-molding processes while maintaining mechanical strength through effective crosslinking.
Solution Approach 2:
The patent replaces the mechanical/thermal sulfur vulcanization system with a chemical crosslinking system based on carbonyl-diamine reactions. This substitution eliminates the need for high-temperature processing and extensive water washing required in traditional sulfur vulcanization, thereby reducing energy consumption and waste water production while achieving the necessary crosslinking for mechanical strength.
2Strength
If sulfur vulcanization system is used for crosslinking, then mechanical strength is achieved, but the process produces harmful waste and requires complex additives
Solution Approach 1:
The patent fundamentally changes the crosslinking chemistry from sulfur-based to carbonyl-based. By using carbonyl groups (from itaconic acid, maleic acid, or other carbonyl-containing compounds) that react with diamine crosslinking agents, the process eliminates sulfur, accelerators, and zinc oxide additives. This parameter change in the chemical system eliminates harmful waste production while maintaining crosslinking effectiveness for mechanical strength.
Solution Approach 2:
The patent extracts and removes the harmful sulfur vulcanization system and its associated additives (accelerators, zinc oxide) from the crosslinking process. By taking out the sulfur-based chemistry and replacing it with carbonyl-diamine crosslinking, the process eliminates the generation of harmful waste products while maintaining the necessary crosslinking for mechanical strength.
3Productivity
If dip-molding process with heavy ceramic formers is used, then elastomeric articles can be produced, but space occupation is large and energy consumption is high
Solution Approach 1:
The patent replaces the mechanical dip-molding process using heavy ceramic formers with a film casting process. The new method involves casting the latex composition onto a flat support, forming a continuous film, and then curing it. This substitution eliminates the need for numerous heavy ceramic formers and their associated handling equipment, thereby reducing space occupation while maintaining production capability through continuous film processing.
Solution Approach 2:
The patent transitions from a three-dimensional dip-molding process using bulky ceramic formers to a two-dimensional film casting process. By changing the processing dimension from volumetric (dipping forms into 3D shapes) to planar (casting films onto flat surfaces), the process significantly reduces space occupation while maintaining productivity through continuous film production that can later be cut and formed into final products.
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
This method reduces water usage and energy consumption, enables efficient production of thin films, and allows for recycling of waste materials, while maintaining mechanical strength and flexibility.
Implementation Method 1
particles of a latex polymer obtainable by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers
Implementation Method 2
a crosslinking component comprising a plurality of functional groups at least one thereof being reactive with the functional groups on the latex polymer particles; the cured film comprises thermally reversible linkages
Data Source
AI summary
The present invention relates to method for the production of a continuous elastomeric film and to continuous elastomeric films and elastomeric articles obtained thereby, where the method comprises:B) providing an aqueous polymer latex composition comprising:(I) particles of a latex polymer obtained by free-radical emulsion polymerization of a mixture of ethylenically unsaturated monomers, the particles bearing a plurality of functional groups, and(II) a crosslinking component comprising a plurality of functional groups at least one thereof being reactive with the functional groups on the latex polymer particles;B) forming from the aqueous polymer latex composition a continuous polymer film;C) optionally drying the continuous polymer film obtained in step B);D) curing the continuous polymer film obtained in step B) or C) to form a continuous elastomeric film; andE) optionally rolling the continuous elastomeric film obtained in step D) into a roll.