Cellulose Ester Fiber Composition for Wet Laid Drainage

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Solution Overview

Problem

Wet laid paper production faces challenges in increasing drainage rates without compromising wet tensile strength, energy efficiency, and maintaining product properties like air and water permeability, while also considering the integration of recycled cellulose fibers and reducing production costs.

Innovation Solution

A composition combining virgin cellulose fibers with cellulose ester staple fibers of specific denier, length, and shape, co-refined together to enhance drainage and mechanical properties, allowing for improved water removal and reduced energy consumption during the drying process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If more refining energy is applied to improve web strength and toughness, then the freeness of the pulp is reduced, but the drainage rate of water from the web becomes slower

Engineering Contradiction:

Improveweb strength and toughnessVSAvoiddrainage rate

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent combines cellulose fibers with hydrophilic synthetic fibers (polyester, nylon, acrylic) to create a composite pulp material. The synthetic fibers act as drainage promoters that do not require extensive refining, allowing the cellulose fibers to be refined to achieve strength while the synthetic fibers maintain high drainage rates, thus resolving the contradiction between web strength and drainage rate.

Inventive Principle:

Principle #40Composite materials

2Productivity

If machine line speed is increased to boost production, then more dryer energy input is required, but energy availability is limited

Engineering Contradiction:

Improveproduction rateVSAvoiddryer energy input

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary drainage promotion by incorporating hydrophilic synthetic fibers into the pulp stock before web formation. This pre-treatment enhances water removal during the forming and pressing stages, so that less energy is required during the drying stage, enabling increased production rates without proportionally increasing dryer energy consumption.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If synthetic fibers are added to improve drainage rate, then web breaks and manufacturing interruptions occur due to fiber damage and refiner plugging, but process complexity increases if synthetic fibers are added after refining

Engineering Contradiction:

Improvedrainage rateVSAvoidweb breaks and manufacturing interruptions

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent specifies particular parameters for the synthetic fibers including fiber diameter (5-20 micrometers), length (3-15 mm), and hydrophilicity to optimize performance. These parameter controls ensure the synthetic fibers are fine enough to pass through refiner screens without plugging, long enough to provide drainage promotion, and hydrophilic enough to work effectively with cellulose fibers, thus resolving the contradiction between drainage improvement and manufacturing reliability.

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 solution enhances drainage rates, maintains wet tensile strength, and improves air and water permeability, enabling increased production speeds while reducing energy input and costs, and is compatible with recycled cellulose fibers.

Implementation Method 1

A composition obtained by combining: virgin cellulose fibers; cellulose ester (CE) staple fibers having a denier per filament (DPF) of less than 3 that are either dry, obtained from solvent spun filaments, or both, and water

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

Wet laid products are generally made by a process in which a stock, or furnish, is prepared by suspending pulped cellulose fibers in water and refining this mixture to prepare a refined pulp slurry or pulp stock

Methodology Applied

Scientific EffectMechanical processing: Mechanical Force

Implementation Method 3

The web layer is generally pressed through the nip of press rolls to further reduced it water content by mechanical means

Methodology Applied

Scientific EffectMechanical compression: Compression

Implementation Method 4

The dried web can then optionally proceed through a sizing press for application of a variety of surface sizing agents. At this stage, because the web is rewet by the application of the sizing agents, the web proceeds through a second drying zone to dry the web to the desired moisture content

Methodology Applied

Scientific EffectThermal evaporation: Evaporation

Data Source

PatentUS11519132B2Composition of matter in stock preparation zone of wet laid process

Publication Date: 2022.12.06 EASTMAN CHEM CO

AI summary

A composition obtained by combining virgin cellulose fibers, cellulose ester (CE) staple fibers having a denier per filament (DPF) of less than 3, and water, and water. The CE staple fibers can also have a short cut length of less than 6 mm and can be crimped. The compositions, when co-refined, are useful to make wet laid products such as paper, cardboard, and filters that have improved water drainage, air permeability, tensile strength, bulk, burst strength, or stiffness, or a combination of these properties.