Jet Mill Pulp Disintegration for Cellulose Acetate

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Solution Overview

Problem

The existing methods for disintegrating pulp for cellulose acetate production, such as those using disc refiners and turbo mills, often result in pulp degradation due to heat generation, leading to increased unreacted components and poor filtration quality, making the cellulose acetate unsuitable for high-quality applications like optical films.

Innovation Solution

A two-step disintegration method involving primary disintegration by a disc refiner to achieve pulp pieces with an average area of not more than 45 cm2, followed by secondary disintegration using a jet mill to exert impact shocks, ensuring even disintegration and reducing pulp degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If pulp is disintegrated by disc refiner or turbo mill, then disintegration is achieved, but heat is generated causing pulp degradation and increased unreacted components

Engineering Contradiction:

Improvedisintegration uniformityVSAvoidpulp degradation

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The disintegration process is divided into two distinct stages: primary disintegration using a disc refiner to achieve rough breakdown, and secondary disintegration using a jet mill for fine particle generation. This segmentation allows each stage to be optimized independently, reducing overall heat generation while achieving complete disintegration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The traditional mechanical shear force mechanism of disc refiners is supplemented and replaced by the jet mill's impact force mechanism. The jet mill uses high-speed rotating blades to generate impact shocks that break pulp into fine particles without the continuous shear heating associated with disc refiners.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If wet disintegration method is used, then disintegration is achieved, but acetic anhydride loss increases and energy consumption rises

Engineering Contradiction:

Improvedisintegration qualityVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

Water is completely removed from the disintegration process. The invention uses purely mechanical dry disintegration methods (disc refiner followed by jet mill) to break pulp into fine particles, eliminating the need for water-based wet disintegration and its associated energy consumption for heating and evaporation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The disintegration process transitions from wet conditions to dry conditions, changing the fundamental parameter of moisture content from present to absent. This parameter change enables the use of impact-based mechanical disintegration rather than wet-based disintegration, reducing energy consumption.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If pulp is not properly disintegrated, then reaction uniformity is poor, but complete disintegration causes heat generation and pulp degradation

Engineering Contradiction:

Improvereaction uniformityVSAvoidheat generation

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The disintegration process is segmented into two stages: primary disintegration for rough breakdown and secondary disintegration for fine particle generation. This segmentation ensures complete disintegration for uniform reaction while controlling heat generation through optimized process parameters at each stage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Primary disintegration is performed as a preliminary step to achieve rough breakdown of pulp before the secondary disintegration step. This preliminary action reduces the workload and heat generation in the final disintegration stage while ensuring complete particle breakdown for uniform reaction.

Inventive Principle:

Principle #10Preliminary action

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 approach effectively reduces unreacted components and improves the filtration quality of cellulose acetate, enabling the production of high-quality cellulose acetate with enhanced filterability and spinnability.

Implementation Method 1

a secondary disintegration step of disintegrating the pulp pieces with an impact shock exerted by a jet mill

Methodology Applied

Scientific EffectImpact force: Impact Force

Data Source

PatentUS10954314B2Method of disintegrating pulp for use in cellulose acetate production and method of producing cellulose acetate

Publication Date: 2021.03.23 DAICEL CORP

AI summary

A method of disintegrating pulp for use in cellulose acetate production includes: a primary disintegration step of disintegrating a pulp sheet into pulp pieces having an average area of not more than 45 cm2; and a secondary disintegration step of disintegrating the pulp pieces with an impact shock exerted by a jet mill (20). The jet mill (20) includes: a cylindrical casing (21) provided with an inlet (21d) and an outlet (21e); and a rotor (25) including a plurality of blades (25a) provided on its outer peripheral portion, the plurality of blades (25a) facing an inner peripheral surface of the casing (21).