Cycloaliphatic Polysulfide Crosslinker for Rubber Wear
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Solution Overview
Problem
Existing organosulfur compounds used as vulcanizing agents for diene rubbers provide inadequate crosslinking, leading to unsatisfactory wear and traction properties in rubber articles, and generate undesirable byproducts during curing, affecting the physical properties and corrosion resistance of the elastomers.
Innovation Solution
A crosslinked polysulfide-containing cycloaliphatic compound is developed, represented by the formula [(C a H 2a -) m G 1< (-C b H 2b S x -) n-m ] o [C c H 2c -G 2< -C d H 2d S y -] p [R] q, which is synthesized through a process involving poly-alkenyl-substituted cycloalkane reactions with thioacid and oxidizing agents, providing improved crosslinking without generating undesirable byproducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional organosulfur compounds with two dithiocarbamate or thiosulfonate groups are used as vulcanizing agents, then the crosslinking density is insufficient, but using compounds with more than two groups introduces unstable linkages that reduce flexibility and generate harmful byproducts
Solution Approach 1:
The invention changes the chemical structure parameters of the vulcanizing agent by using cycloaliphatic compounds with multiple reactive sulfur groups (dithiocarbamate or thiosulfonate) attached to a cyclic carbon framework. This structural modification allows achieving higher crosslinking density (o > 50) while maintaining stable linkages through the cyclic structure, avoiding the unstable ether or ester linkages found in linear counterparts.
Solution Approach 2:
The invention creates a composite molecular structure combining cycloaliphatic hydrocarbon frameworks with multiple sulfur-containing functional groups. This composite approach integrates the structural stability of cyclic hydrocarbons with the reactive crosslinking capability of organosulfur compounds, achieving both high crosslinking density and linkage stability simultaneously.
2Strength
If organosulfur compounds with multiple reactive groups are used to improve crosslinking, then wear and traction properties improve, but undesirable byproducts are generated during curing that affect corrosion resistance and physical properties
Solution Approach 1:
The invention converts the potential harm of multiple reactive groups generating byproducts into a benefit by designing a cyclic molecular structure where the byproducts of curing (such as H2S or other volatile sulfur compounds) can be more easily controlled and removed. The cyclic structure provides a controlled reaction pathway that minimizes harmful byproduct formation while maintaining effective crosslinking.
3Ease of manufacture
If linear polysulfide structures are used as binders, then synthesis is simpler, but they lack the flexibility and energy dissipation capability needed to prevent crack propagation
Solution Approach 1:
The invention applies the principle of curvature by using cycloaliphatic (cyclic) structures instead of linear chains. The cyclic framework provides inherent flexibility and the ability to undergo conformational changes that allow energy dissipation during deformation, preventing crack propagation while maintaining structural integrity. The cyclic structure acts as a flexible joint that can absorb mechanical stress.
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 crosslinked polysulfide compound enhances the wear resistance and tear properties of rubber articles while maintaining hardness and controlling tan delta values across different temperatures, without producing harmful byproducts during the curing process.
Implementation Method 1
Elemental sulfur is commonly used as a vulcanizing agent for unsaturated diene elastomers (rubbers). The crosslinks formed with sulfur are primarily polysulfidic crosslinks that increase the thermal stability of the elastomer vulcanizates.
Implementation Method 2
reacting free poly-mercaptan-functional alkylcycloalkane with an oxidizing agent selected from halogenated sulfur-containing compound
Data Source
AI summary
A crosslinked polysulfide-containing cycloaliphatic compound, useful as a crosslinker for filled sulfur-vulcanizable elastomer compositions, is represented by the general formula: [(CaH2a-)mG1(-CbH2bSx-)n-m and CcH2c-G2- CdH2dSy- ]p[R]q wherein G1 is a saturated, monocyclic aliphatic group of valence n containing from 5 to 12 carbon atoms and optionally containing at least one halogen or a saturated monocyclic silicone [RSiO-]n[R2SiO-]r group of valence n; G2 is a saturated, divalent cyclic aliphatic group of valence 2 containing from S to 12 carbon atoms and optionally containing at least one halogen or a saturated monocyclic silicone [RSiO-]n[R2SiO-]r group of valence n;; each R independently is a selected from the group consisting of a hydrogen atom, monovalent hydrocarbon of up to 20 carbon atoms and a halogen atom; each occurrence of subscripts a, b, c, d, m, n, o, p, q, x and y independently is an integer wherein a is 2 to 6; b is 2 to 6; c is 1 to 6; d is 1 to 6; m is 1 or 2; n is 3 to 5; o is a positive integer, p is 0 or a positive integer; q is a positive integer; r is an integer of from 0 to 3; x is 1 to 10 and y is 1 to 10, with the provisos that, (i) at least one x is 2 to 10; (ii) the ratio of p to o is less than 1 to 5; and q is equal to the sum of unfilled valences of the (CaH2a-)mG1(-CbH2bSx-)n-m and CcH2c-G2- CdH2dSy- groups.