Dip Molding Emulsion pH Control and Crosslinking
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Solution Overview
Problem
Conventional methods for producing gloves using sulfur-based crosslinking agents result in allergic reactions and require volatile bases, making it difficult to control pH and leading to reduced tensile strength and fatigue durability, while existing polycarbodiimide-crosslinked glove production methods struggle to integrate with established sulfur-based vulcanization accelerator technologies.
Innovation Solution
A dip molding composition containing a (meth)acrylonitrile-derived structural unit, unsaturated carboxylic acid-derived structural unit, and butadiene-derived structural unit, along with a polycarbodiimide and alkali metal hydroxide, is used to produce a glove, with specific conditions to ensure crosslinking and maintain pH between 9.5 to 10.5, incorporating zinc oxide or aluminum complex as metal crosslinking agents, and controlling the content of calcium and potassium to enhance tensile strength and fatigue durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfur-based crosslinking agents are used, then crosslinking reaction occurs, but type IV allergy is caused
Solution Approach 1:
The patent extracts and removes the harmful sulfur-based crosslinking agent from the system while maintaining the essential crosslinking function through alternative agents (polycarbodiimide, carbonyl diimidazole, or carbonyl diazole), thereby eliminating type IV allergy while preserving crosslinking reaction
Solution Approach 2:
The patent employs alternative crosslinking agents that are less harmful and can be used in disposable medical gloves, replacing the persistent harmful effects of sulfur-based agents with shorter-lived, safer chemical alternatives
2Ease of operation
If volatile base is used as pH modifier, then pH adjustment is achieved, but pH control becomes difficult and tensile strength decreases
Solution Approach 1:
The patent changes the physical state parameter of the pH modifier from volatile (ammonium hydroxide) to non-volatile (alkali metal hydroxide), thereby maintaining pH adjustment capability while achieving stable pH control and improved tensile strength
3Reliability
If ammonium hydroxide is used as pH modifier, then crosslinking of polycarbodiimide is enabled, but irritating odor and equipment corrosion occur
Solution Approach 1:
The patent extracts and removes the volatile ammonium hydroxide from the system, replacing it with non-volatile alkali metal hydroxide, thereby eliminating irritating odor and equipment corrosion while maintaining crosslinking reaction through alternative mechanisms
Solution Approach 2:
The patent introduces alkali metal hydroxide as an intermediary substance that enables crosslinking through a different chemical mechanism (forming carboxylate salts that react with polycarbodiimide), replacing the direct volatile ammonia mechanism
4Ease of manufacture
If sulfur-based vulcanization accelerator technology is used, then established production technology is maintained, but integration with polycarbodiimide-crosslinked glove production is difficult
Solution Approach 1:
The patent develops a universal dip molding composition system that can accommodate multiple crosslinking mechanisms (polycarbodiimide, carbonyl diimidazole, carbonyl diazole) within a single production framework, enabling integration of advanced crosslinking technology with established manufacturing processes
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 produces gloves with excellent fatigue durability and higher tensile strength without the irritating odor of ammonia or equipment corrosion, effectively integrating with existing technologies by using alkali metal hydroxide as a pH modifier, achieving a glove with 20 MPa tensile strength and 240 minutes or longer fatigue durability.
Implementation Method 1
a crosslinking reaction between a carboxyl group of an XNBR and a polycarbodiimide
Implementation Method 2
the dip molding composition has a pH of 9.5 to 10.5
Implementation Method 3
incorporating zinc oxide or aluminum complex as metal crosslinking agents
Data Source
AI summary
Provided is, a glove production method including: (1) the step of immersing a glove forming mold in a liquid coagulant containing calcium ions so as to allow the coagulant to adhere to the glove forming mold; (2) the dispersion step of leaving a dip molding composition to stand with stirring; (3) the dipping step; (4) the gelling step; (5) the leaching step; (6) the beading step; (7) the precuring step; and (8) the curing step, in which method the steps (3) to (8) are performed in the order mentioned, and the dip molding composition has a specific formulation.