Liquid Lignin Polyol Synthesis via Controlled Alkoxylation

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Solution Overview

Problem

Current methods for producing lignin polyols face challenges such as significant homopolymerization, self-condensation leading to non-soluble fractions, and limitations in application due to aqueous environments, resulting in the need for additional processing steps like filtration and restricted use in polymer production, especially with water-reactive species like urethanes.

Innovation Solution

A method involving dispersing lignin in polyols like diethylene glycol or propoxylated glycerol, adding a catalyst, removing excess water, and reacting with an alkoxide at controlled temperatures, followed by neutralization and optional filtration with silicate compounds to produce liquid lignin polyols without homopolymers or precipitates, suitable for use with isocyanates to form thermoset products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional alkoxylation methods are used to produce lignin polyols, then lignin modification is achieved, but significant homopolymerization of propylene oxide occurs reducing process control

Engineering Contradiction:
Improveprocess controlVSAvoidhomopolymer formation
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by carefully controlling reaction temperature (20-80°C), catalyst type and amount, and alkoxide addition rate to suppress homopolymerization while maintaining effective alkoxylation of lignin. This resolves the contradiction by optimizing reaction parameters to favor desired product formation over unwanted side reactions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses an intermediary approach by employing a catalyst system that mediates the alkoxylation reaction between lignin and propylene oxide. The catalyst enables selective reaction at controlled rates, preventing runaway homopolymerization while ensuring complete lignin modification.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional alkoxylation conditions are applied, then lignin polyol is produced, but self-condensation of lignin creates non-soluble fractions requiring additional filtration

Engineering Contradiction:
Improvepolyol productionVSAvoidfiltration steps
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent changes reaction parameters including temperature control (20-80°C), catalyst selection, and alkoxide addition methodology to prevent self-condensation of lignin macromolecules. By maintaining controlled conditions, the process produces fully soluble polyol without requiring additional filtration steps, thus resolving the contradiction between ease of manufacture and process complexity.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If aqueous environment is used for lignin modification, then reaction proceeds, but application in water-reactive polymer production is limited

Engineering Contradiction:
Improveapplication rangeVSAvoidwater reactivity limitation
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent fundamentally changes the reaction environment from aqueous to anhydrous conditions by using alkoxides and controlling water content. This parameter change enables the lignin polyol to be used with water-reactive species like isocyanates, expanding adaptability to polymer production applications while eliminating the harmful limitation of water reactivity.

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If conventional methods are used to produce lignin polyols, then modification is achieved, but liquid polyols without homopolymers and precipitates cannot be obtained

Engineering Contradiction:
Improvepolyol qualityVSAvoidadditional processing steps
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies comprehensive parameter changes including temperature control (20-80°C), catalyst optimization, alkoxide addition rate control, and water removal to produce high-quality liquid lignin polyols free from homopolymers and precipitates. These parameter optimizations achieve both high manufacturing precision and productivity by eliminating the need for additional processing steps.

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 yields liquid lignin polyols that produce excellent thermoset products when reacted with isocyanates, eliminating the need for filtration and expanding application possibilities beyond traditional polymer uses, including thermal insulation and construction applications.

Implementation Method 1

adding a catalyst

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 2

filtrating the polyol with a silicate compound, such as magnesium silicate, to remove traces of neutralized catalyst

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP3077447B1A composition in the form of a lignin polyol, a method for the production thereof and use thereof
Publication Date: 2022.02.23 STORA ENSO OYJ
  • EP3077447B1 patent drawingFigure 1
  • EP3077447B1 patent drawingFigure 2
  • EP3077447B1 patent drawingFigure 3a)~3b)

AI summary

The present invention relates to a composition comprising a lignin polyol, a method for the manufacturing of said composition and use thereof in different application areas, such as in adhesives, binders, castings,foams (such as in rigid polyurethaneand polyisocyanurate foams for thermal insulation and construction applications, semi-rigid, flexible, moulded, laminated, microcellular and viscoelastic polyurethane foams), fillers, glues, sealants, elastomers and rubbers. The present invention also relates to a method for the manufacturing of a foam and use of this foam.