Oxidized Cellulose Microsphere Dissolution Process

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Solution Overview

Problem

Traditional cellulose dissolution processes are cumbersome, expensive, and require harsh conditions, leading to cellulose degradation and limited solvent compatibility, which hinders the full exploitation of cellulose potential in various industries.

Innovation Solution

A process involving the formation of a modified cellulose solution by contacting cellulose with a solvent and a salt under an inert atmosphere, adjusting temperatures to minimize degradation and enhance solubility, using solvents like N,N-Dimethylacetamide and salts such as lithium halides, to achieve a stable and efficient cellulose solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional cellulose dissolution processes are used, then cellulose can be dissolved, but the process becomes cumbersome and expensive with harsh conditions leading to cellulose degradation

Engineering Contradiction:
Improvecellulose dissolution effectivenessVSAvoidcellulose degradation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the dissolution system by using lithium halide salts in N,N-dimethylacetamide solvent, which allows cellulose dissolution at lower temperatures (115-145°C) compared to traditional methods, thereby reducing thermal degradation while maintaining dissolution effectiveness

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs an inert atmosphere during the dissolution process to prevent oxidative degradation of cellulose, eliminating the need for harsh oxidizing conditions while maintaining dissolution effectiveness

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

2Reliability

If traditional cellulose dissolution processes are used, then cellulose can be dissolved, but excessive physical manipulation and lengthy treatment periods cause degradation

Engineering Contradiction:
Improvecellulose dissolution effectivenessVSAvoidtreatment period
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent modifies the dissolution parameters by using lithium halide-solvent complexes that rapidly penetrate cellulose structure, reducing the treatment time from hours to minutes while maintaining complete dissolution and preserving molecular weight

Inventive Principle:
Principle #35Parameter changes

3Reliability

If traditional cellulose dissolution processes are used, then cellulose can be dissolved, but the process requires unusual solvents with high ionic strength under harsh conditions

Engineering Contradiction:
Improvecellulose dissolution effectivenessVSAvoidprocess simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the solvent system from traditional harsh solvents (like cuprammonium or xanthate) to a more manageable lithium halide in N,N-dimethylacetamide system, which provides effective dissolution under milder, more controllable conditions

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The lithium halide acts as an intermediary substance that facilitates cellulose dissolution by forming soluble complexes, enabling the process to proceed under milder conditions without requiring unusual or harsh solvents

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If high thermal treatment is applied to dissolve cellulose, then dissolution is achieved, but oxidized groups are removed from oxidized cellulose

Engineering Contradiction:
Improvecellulose solubilityVSAvoidoxidized groups
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent lowers the treatment temperature range to 115-145°C, which is sufficient for dissolution but below the threshold that causes significant removal of oxidized groups, thereby preserving the functional properties of oxidized cellulose

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The inert atmosphere prevents oxidative degradation and loss of oxidized groups during the dissolution process, allowing effective dissolution at lower temperatures while maintaining the integrity of oxidized cellulose functional groups

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

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 process minimizes cellulose degradation, allows for effective solubility with reduced thermal and mechanical stress, and maintains the molecular weight and degree of oxidation of the dissolved cellulose, enabling its broader industrial applications.

Implementation Method 1

forming a mixture by contacting a modified cellulose with a solvent under an inert atmosphere to form a swelled modified cellulose

Methodology Applied
Scientific EffectSolvation: Solvation

Implementation Method 2

adjusting the mixture to a first temperature from about 115° C to about 145° C

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

contacting the swelled modified cellulose with a salt under the inert atmosphere to form a modified cellulose solution

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 4

adjusting the modified cellulose solution to a second temperature from about 90° C to about 120° C

Methodology Applied
Scientific EffectCooling: Cooling

Data Source

PatentEP3103442B1Microspheres including oxidized cellulose
Publication Date: 2021.05.12 COVIDIEN LP
  • EP3103442B1 patent drawingFigure 1~5
  • EP3103442B1 patent drawingFigure 6~7
  • EP3103442B1 patent drawingFigure 8A

AI summary

A process for forming microspheres comprising: forming a first plurality microspheres comprising a biodegradable polymer; contacting the first plurality of microspheres with a modified cellulose solution to form a discontinuous phase liquid; and contacting the discontinuous phase liquid with a continuous phase liquid to form an emulsion; and extracting a second plurality of microspheres from the emulsion, the second plurality of microspheres comprising the first plurality of microspheres.