Guayule Polyisoprene Latex Dispersion for Stable Dip-Molding Solids

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Solution Overview

Problem

Existing methods lack a reliable process for producing stable polyisoprene latex dispersions with optimized polymer chain distributions, color, viscosity, and weight percent solids, particularly for dip-molding applications.

Innovation Solution

A process involving dispersing cis-1,4-polyisoprene rubber cement into an aqueous surfactant mixture, followed by de-solventization to produce a latex dispersion, and adjusting the weight percent solids through centrifugation and dilution, utilizing guayule plant material as a source for cis-1,4-polyisoprene.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional methods are used to produce cis-1,4-polyisoprene latex dispersions, then production is simpler, but the polymer chain distributions, color, viscosity, and weight percent solids are not optimized

Engineering Contradiction:

Improvepolymer chain distribution optimizationVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The production process is divided into distinct stages: extraction of cis-1,4-polyisoprene from natural sources, controlled emulsion formation with specific surfactants, staged polymerization processes, and sequential purification steps. Each stage is independently optimized to control polymer chain distribution and maintain product quality parameters.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method performs preliminary actions by pre-preparing optimized surfactant mixtures, pre-controlling emulsion pH and ionic strength, and pre-establishing polymerization conditions before actual latex formation. This preliminary preparation ensures that when polymerization occurs, the polymer chain distribution and other parameters are already optimized.

Inventive Principle:

Principle #10Preliminary action

2Strength

If natural rubber is used, then remarkable resilience and tensile strength are achieved, but allergenic proteins are present

Engineering Contradiction:

Improvetensile strengthVSAvoidallergenic protein content

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The method extracts and isolates cis-1,4-polyisoprene from natural rubber sources while systematically removing allergenic proteins through multiple purification steps including solvent extraction, filtration, and centrifugation. The resulting latex dispersion contains the desired polyisoprene polymer chains with minimal protein content, maintaining strength while reducing allergenicity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The purification process applies different treatment methods to different components: gentle extraction for the polyisoprene polymer chains to preserve their structural integrity and strength properties, while applying more aggressive removal techniques specifically targeted at protein contaminants. This selective treatment maintains local quality of the desired polymer while eliminating harmful proteins.

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If high shear rate dispersing is used (>20,000 rad/sec), then emulsion formation is improved, but energy consumption increases

Engineering Contradiction:

Improveemulsion stabilityVSAvoidenergy consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The method optimizes the shear rate parameter to a specific range above 20,000 rad/sec that achieves effective emulsion formation and stability. By precisely controlling this parameter rather than using excessively high shear rates, the process achieves the necessary emulsion stability while minimizing energy consumption. The surfactant concentration and other parameters are also adjusted to work synergistically with the shear rate to reduce overall energy requirements.

Inventive Principle:

Principle #35Parameter changes

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 latex dispersions with enhanced mechanical stability, low antigenic protein content, and controlled particle size, suitable for dip-molding processes.

Implementation Method 1

dispersing takes place at a shear rate of greater than 20,000 rad/sec

Methodology Applied

Scientific EffectShear mixing: Shear Stress

Implementation Method 2

removing the at least one organic solvent from the latex emulsion to produce the aqueous polyisoprene latex

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

subjecting the latex dispersion obtained by de-solventization to at least one round of centrifugation into phases

Methodology Applied

Scientific EffectCentrifugal separation: Centrifugal Force

Data Source

PatentUS12624131B2Methods for producing polyisoprene latex dispersions

Publication Date: 2026.05.12 BRIDGESTONE CORP

AI summary

In various embodiments, methods for producing aqueous polyisoprene latex from natural cis-1,4-polyisoprene are described. The natural cis-1,4-polyisoprene may be sourced from guayule scrubs. In various embodiments, the method comprises extracting guayule plant material to form a miscella, fractionating the miscella to a preliminary cement, diluting the preliminary cement to a cement for dispersing, dispersing the cement in an aqueous surfactant mixture under high shear to produce an emulsion, and de-solventizing the emulsion to produce an aqueous latex dispersion. The rubber solids level can then be adjusted by centrifugation and dilution in water to produce a final aqueous cis-1,4-polyisoprene latex.