Silicone Oil Emulsion Stabilization via Block Copolymers

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Solution Overview

Problem

Current methods for incorporating water-incompatible silicone oils with poly(dimethylsilyloxy) groups into water-based coatings face challenges such as phase separation, haze, and poor weather durability due to the use of high amounts of surfactants or chemical modification, which can lead to instability and environmental concerns.

Innovation Solution

Aqueous emulsions are created by dispersing non-polar silicone oils with poly(dimethylsilyloxy) groups using block copolymers derived from (meth)acrylates and (meth)acrylic acids in a controlled radical polymerization process, eliminating the need for additional surfactants and maintaining the silicone oil's surface-active properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If high molecular weight silicone oils are used to provide greater lubrication and slip, then the coefficient of friction is reduced and mar resistance is improved, but the viscosity of the material increases making it difficult to add and disperse in water-borne coatings

Engineering Contradiction:

Improveslip and mar resistanceVSAvoiddispersibility in water-borne coatings

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The silicone oil is segmented into microscopic droplets dispersed throughout the aqueous phase, with each droplet stabilized by surfactant molecules. This segmentation allows high molecular weight silicone oil to be incorporated into water-borne coatings without requiring high viscosity, as the individual droplets remain suspended rather than forming a continuous viscous phase.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Surfactants act as intermediary molecules between the hydrophobic silicone oil and the hydrophilic aqueous phase. The surfactant molecules have hydrophobic tails that associate with the silicone oil droplets and hydrophilic heads that interact with water, enabling dispersion of high molecular weight silicone oil in water-borne systems without compromising slip and mar resistance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If surfactants are used to stabilize silicone oil emulsions and prevent phase separation, then emulsion stability is improved, but large amounts of surfactant (up to 30 wt.-%) are introduced causing undesirable characteristics including poor weather durability, haze, fogging, and environmental concerns

Engineering Contradiction:

Improveemulsion stabilityVSAvoidhaze, fogging, poor weather durability, environmental impact

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent optimizes the surfactant concentration parameter to a specific range (0.1-10 wt.-% based on silicone oil weight) that provides sufficient emulsion stability while avoiding the harmful effects associated with high surfactant levels. This parameter optimization balances stability requirements with film quality and environmental considerations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The formulation creates a composite system combining silicone oil, surfactant, and water in specific proportions and ratios. By carefully controlling the composition and interactions between these components, the patent achieves stable emulsions with reduced surfactant content, minimizing haze, fogging, and weathering issues while maintaining emulsion stability.

Inventive Principle:

Principle #40Composite materials

3Ease of operation

If silicone oils are incorporated into water-based formulations, then slip and lubricity are improved, but phase separation occurs upon storage leading to severe cratering of the coating and haze after curing

Engineering Contradiction:

Improveslip and lubricityVSAvoidphase separation resistance

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

Surfactants serve as intermediary agents that prevent phase separation by forming stable interfaces between the silicone oil and aqueous phases. The surfactant molecules adsorb at the oil-water interface, reducing interfacial tension and preventing coalescence of silicone oil droplets, thereby maintaining homogeneous dispersion and preventing cratering and haze during storage and curing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses relatively small amounts of surfactant (0.1-10 wt.-% based on silicone oil) as a temporary stabilizing agent that performs its function during storage and application. The surfactant provides necessary stability during the product's shelf life and application process without requiring large quantities that would cause long-term film defects.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS11292906B2Aqueous silicone polymer emulsion

Publication Date: 2022.04.05 BASF SE

AI summary

Aqueous silicone polymer emulsion The presently claimed invention relates to a composition in form of an emulsion of water incompatible silicone oil comprising droplets of silicone oil dispersed in a continuous aqueous phase. The composition provides better slip and mar resistance, anti-blocking properties and optical properties to the coating formulations, printing ink, personal care product compositions, textiles, leather and indirect food contact applications.