Carboxyl-Containing Diene Rubber Latex with Low SP Plasticizer
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Solution Overview
Problem
Conventional latex compositions for film-shaped molded articles, such as dip-molded gloves, often lack sufficient elongation and durability while maintaining tensile strength and texture, particularly when in contact with the human body, due to the presence of natural rubber latex proteins causing allergic reactions.
Innovation Solution
A latex composition comprising carboxyl group-containing conjugated diene rubber with a specific plasticizer having a solubility parameter (SP value) of 15 (cal/cm3)1/2 or less, along with a metal compound and sulfur as a cross-linking agent, to enhance tensile strength, elongation, and durability, while forming a supple texture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If natural rubber latex is used in film-shaped molded articles, then the texture and tensile strength are excellent, but allergic reactions occur due to protein content
Solution Approach 1:
The patent removes the harmful protein component from natural rubber latex by using synthetic rubber alternatives (styrene-butadiene rubber, nitrile rubber, carboxyl group-containing conjugated diene rubber) that provide similar mechanical properties without the allergic reaction risk. This extraction of the harmful element while retaining the beneficial mechanical properties resolves the contradiction between excellent texture/tensile strength and allergic reactions.
2Object-affected harmful factors
If synthetic rubber latex is used to avoid allergic reactions, then allergic symptoms are reduced, but elongation and durability are insufficient
Solution Approach 1:
The patent optimizes the composition parameters of synthetic rubber by specifying precise ranges for each component: styrene-butadiene rubber (65-84.5 parts), nitrile rubber (15-25 parts), carboxyl group-containing conjugated diene rubber (0.5-10 parts), and plasticizer (0.1-15 parts). This parameter optimization achieves both low allergenicity and improved elongation (400-600%) and durability, resolving the contradiction between avoiding allergic reactions and maintaining durability.
Solution Approach 2:
The patent creates a composite rubber composition by combining multiple synthetic rubber types (styrene-butadiene rubber, nitrile rubber, carboxyl group-containing conjugated diene rubber) with plasticizers and crosslinking agents. This composite approach synergistically improves both the safety profile (low allergenicity) and performance characteristics (elongation and durability) that individual synthetic rubbers cannot achieve alone.
3Object-affected harmful factors
If conventional synthetic rubber composition is used, then allergic reactions are avoided, but elongation and stress retention are not sufficient
Solution Approach 1:
The patent introduces plasticizers as intermediary substances that mediate between the rigid rubber polymer chains, allowing them to move more freely and improve elongation properties. The plasticizer content (0.1-15 parts per 100 parts of rubber) acts as a lubricant between polymer chains, enabling the material to stretch further while maintaining structural integrity and stress retention, thus improving elongation without compromising safety.
Solution Approach 2:
The patent systematically optimizes the ratios of rubber components and additives to achieve target elongation (400-600%) and stress retention properties. By adjusting the composition parameters within specified ranges and implementing controlled crosslinking, the patent simultaneously achieves low allergenicity and superior mechanical performance including elongation and stress retention.
4Strength
If plasticizer content is increased to improve texture and elongation, then supple texture is achieved, but tensile strength and durability decrease
Solution Approach 1:
The patent precisely controls the plasticizer content within the range of 0.1-15 parts per 100 parts of carboxyl group-containing conjugated diene rubber. This optimized parameter range ensures that the plasticizer provides sufficient lubrication between polymer chains for supple texture and good elongation, while maintaining adequate tensile strength and durability through controlled crosslinking and balanced composition.
Solution Approach 2:
The patent creates a balanced composite formulation where plasticizers work synergistically with crosslinking agents and multiple rubber components. The crosslinking network provides structural integrity and tensile strength, while the plasticizer provides chain mobility for elongation and supple texture. This composite approach resolves the contradiction by having different components fulfill different functions.
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 latex composition achieves high tensile strength, large elongation, and excellent durability, along with a supple texture, effectively addressing the limitations of existing compositions by improving the mechanical properties and wear endurance of film-shaped molded articles.
Implementation Method 1
a specific plasticizer to be within a predetermined range... a plasticizer (B) having a SP value of 15 (cal/cm3)1/2 or less
Implementation Method 2
along with a metal compound and sulfur as a cross-linking agent, to enhance tensile strength, elongation, and durability
Data Source
AI summary
A latex composition has a latex of a carboxyl group-containing conjugated diene rubber (A), and a plasticizer (B) having a SP value of 15 (cal/cm3)1/2 or less, wherein the content of a plasticizer (B) is 0.1 to 15 parts by weight based on 100 parts by weight of the carboxyl group-containing conjugated diene rubber (A) included in the latex.