PHMS/PDMS Copolymer Coating for Pigment Thermal Stability

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Solution Overview

Problem

The use of inorganic pigments like titanium dioxide in polycarbonate and other polymer compositions is hindered by surface coatings that can interact adversely with the polymer during processing, leading to stability issues and significant loss of organic treating agents like PHMS at high temperatures.

Innovation Solution

A process involving the deposition of a PHMS/PDMS copolymer or a combination of this copolymer and a neat PHMS polymer on the surfaces of inorganic pigment particles to form a stable coating that withstands high processing temperatures and minimizes hydrogen evolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PHMS is deposited on the surfaces of inorganic pigment particles to improve processability and performance, then the pigment performance is enhanced, but significant loss of PHMS occurs at high processing temperatures

Engineering Contradiction:

Improvepigment performanceVSAvoidPHMS loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies composite materials by combining PHMS with PDMS to create a copolymer coating. The PHMS component provides the desired pigment performance enhancement, while the PDMS component contributes thermal stability. This composite coating structure allows the coating to maintain its integrity at high processing temperatures, preventing the 50-60% PHMS loss that occurs with pure PHMS coatings.

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If PHMS is used as a surface coating to improve pigment processability, then processability is enhanced, but hydrogen evolution creates explosive environments and degrades the coating

Engineering Contradiction:

ImproveprocessabilityVSAvoidhydrogen evolution

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a differentiated coating structure where PHMS and PDMS segments are distributed throughout the coating matrix. The PDMS segments act as thermal stabilizers localized within the coating, suppressing hydrogen evolution from PHMS at high temperatures. This local stabilization prevents explosive hydrogen environments while preserving the processability benefits of PHMS.

Inventive Principle:

Principle #3Local quality

3Reliability

If surface coatings are deposited on inorganic pigment particles to enhance specific properties, then opacity and light stability are improved, but the coatings can adversely interact with the polymer during processing

Engineering Contradiction:

Improveopacity and light stabilityVSAvoidpolymer stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies the intermediary principle by using PDMS as a mediator within the coating structure. The PDMS segments act as a buffer between the PHMS coating and the polycarbonate polymer, preventing adverse interactions during high-temperature processing. This intermediary presence maintains both the optical properties provided by PHMS and the stability of the polycarbonate matrix.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 proposed solution significantly reduces the loss of the organic treating agent during high-temperature processing, enhances the stability of the polymer composition, and improves the bulk density of the treated pigment, leading to better performance in polycarbonate compositions.

Implementation Method 1

depositing an organic treating agent on the surfaces of the pigment particles to form at least one coating of the organic treating agent thereon

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

the active hydrogen in PHMS is highly reactive at high temperatures... the PHMS/PDMS copolymer... can withstand the high temperatures associated with the pigment finishing process

Methodology Applied

Scientific EffectThermal stability: Thermal Insulation

Data Source

PatentUS20250026908A1Inorganic pigment treated with PHMS/PDMS copolymer

Publication Date: 2025.01.23 TRONOX LLC

AI summary

A process for producing a treated, inorganic pigment is provided. The process comprises providing a plurality of inorganic pigment particles, and depositing an organic treating agent on the surfaces of the pigment particles to form at least one coating of the organic treating agent thereon. The organic treating agent is selected from the group consisting of a copolymer of polyhydromethylsiloxane (PHMS) and polydimethylsiloxane (PDMS) (a “PHMS/PDMS copolymer”), and a combination of a PHMS/PDMS copolymer and a neat PHMS polymer. A treated, inorganic pigment is also provided.