Composite Polymer Particles via Cellulose Stabilized Suspension

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Solution Overview

Problem

Existing methods for producing polymer particles by suspension polymerization face challenges such as wide particle size distribution, generation of fine particles, and the need for extensive washing to remove stabilizers, which complicates the production process and can lead to inorganic substances detaching from particle surfaces, affecting product characteristics.

Innovation Solution

A method involving aqueous suspension polymerization with small polymer particles having a volume-average particle size of 20 to 500 nm, where a water-soluble cellulose compound adsorbs on the surfaces of these small particles, stabilizing them and allowing them to adhere to larger polymer particles, thereby simplifying the washing process and improving particle flowability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If inorganic compounds are used as suspension stabilizer, then particle size distribution is narrowed, but inorganic compounds detach from particle surfaces affecting product characteristics

Engineering Contradiction:

Improveparticle size distributionVSAvoidproduct characteristics

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent uses a composite stabilizer system combining inorganic compounds (silica, aluminum hydroxide, calcium carbonate) with organic compounds (polyvinyl alcohol, gelatin, starch). The inorganic compounds provide particle size control while the organic compounds form protective films on particle surfaces, preventing detachment and maintaining product characteristics.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The organic suspension stabilizer acts as an intermediary between the inorganic compound particles and the aqueous medium. It adsorbs onto the inorganic particle surfaces, providing steric or electrostatic stabilization that prevents both coalescence during polymerization and detachment from the final polymer particles, thus resolving the contradiction between size control and stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If inorganic compounds are used as suspension stabilizer, then particle size distribution is narrowed, but extensive washing is required to remove adhering inorganic substances

Engineering Contradiction:

Improveparticle size distributionVSAvoidwashing process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

By combining inorganic and organic stabilizers, the patent reduces the amount of inorganic compound needed while maintaining particle size control. The organic stabilizer provides sufficient stabilization, minimizing inorganic residue that would require washing, thus simplifying the production process.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical nature of the stabilizer system from predominantly inorganic to a composite organic-inorganic system. This parameter change reduces the quantity of inorganic substances adhering to particles, thereby reducing washing requirements and process complexity while maintaining narrow particle size distribution.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If water-soluble polymers are used as suspension stabilizer, then emulsion polymerization generates fine particles, but particle size distribution becomes wide

Engineering Contradiction:

Improvefine particle generationVSAvoidparticle size distribution

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent combines water-soluble polymers with inorganic compounds to create a composite stabilizer system. The inorganic component provides rigid structural support that prevents excessive fine particle generation, while the polymer ensures adequate dispersion and stabilization, achieving both narrow particle size distribution and controlled fine particle formation.

Inventive Principle:

Principle #40Composite materials

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

This method achieves stable dispersion of monomer droplets, reduces the need for extensive washing, and enhances particle flowability by creating composite particles with small polymer particles adhering to larger ones, resulting in improved product characteristics and simplified production.

Implementation Method 1

a water-soluble cellulose compound adsorbing on surfaces of the small polymer particles

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

small polymer particles adhering to surfaces of the large polymer particles

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10174190B2Composite particles, method for producing composite particles, and use thereof

Publication Date: 2019.01.08 SEKISUI PLASTICS CO LTD

AI summary

There are provided a method for producing particles by suspension polymerization which ensures an excellent dispersion stability of the monomer and a simpler washing step, composite particles obtainable by this production method, and use of the composite particles. The method for producing composite particles includes a polymerization step of subjecting a monomer mixture which contains a polymerizable vinyl monomer to aqueous suspension polymerization in a presence of small polymer particles having a volume-average particle size of 20 to 500 nm, with a water-soluble cellulose compound adsorbing on surfaces of the small polymer particles, and thereby obtaining composite particles which contain the small polymer particles and large polymer particles greater than the small polymer particles.