Surface Enhanced Pulp Fibers for Paper Strength and Softness

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Solution Overview

Problem

Conventional paper products, such as tissues and paper towels, face a trade-off between strength and softness, with increasing strength often compromising softness, and fibrillated fibers used to enhance strength can increase manufacturing costs and energy requirements due to low freeness and higher drying energy needs.

Innovation Solution

Incorporating surface-enhanced pulp fibers (SEPF) that are highly fibrillated to increase fiber surface area while maintaining fiber length, combined with unrefined or lightly fibrillated hardwood and softwood fibers, allowing for a lower basis weight while achieving comparable softness and enhanced strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional fibrillated fibers are used to increase strength, then paper strength is improved, but drying energy requirements increase due to low freeness

Engineering Contradiction:

Improvepaper strengthVSAvoiddrying energy

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by controlling the degree of fibrillation of specific fiber populations (softwood fibers at 2-6 kWh/ton, hardwood fibers at 0-2 kWh/ton) rather than highly fibrillating all fibers. This selective parameter adjustment maintains adequate strength while improving freeness and reducing drying energy compared to conventional high-fibrillation approaches.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements local quality by differentiating the fibrillation treatment for different fiber types within the furnish. Softwood fibers receive moderate fibrillation (2-6 kWh/ton) to provide strength, while hardwood fibers receive light or no fibrillation (0-2 kWh/ton) to maintain high freeness and reduce drying energy, creating localized functional zones within the paper structure.

Inventive Principle:

Principle #3Local quality

2Strength

If the proportion of strengthening fibers is increased to improve strength, then paper strength is improved, but softness deteriorates

Engineering Contradiction:

Improvepaper strengthVSAvoidsoftness

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent applies local quality by assigning different fiber types to different functional roles within the paper structure. Softwood fibers (20-40% of furnish) are moderately fibrillated to provide strength, while hardwood fibers (60-80% of furnish) are lightly fibrillated to provide softness and bulk, creating a functionally differentiated composite structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements composite materials by combining two distinct fiber populations with different properties and fibrillation levels. The softwood-hardwood composite furnish leverages the strength-contributing characteristics of softwood fibers and the softness-contributing characteristics of hardwood fibers, achieving a balance that neither fiber type could provide alone.

Inventive Principle:

Principle #40Composite materials

3Strength

If basis weight is increased to achieve suitable strength, then paper strength is improved, but product weight increases

Engineering Contradiction:

Improvepaper strengthVSAvoidproduct weight

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The patent applies parameter changes by optimizing the fibrillation energy parameters for each fiber type to achieve maximum strength contribution per unit weight. The controlled fibrillation of softwood fibers (2-6 kWh/ton) and light fibrillation of hardwood fibers (0-2 kWh/ton) creates a furnish that achieves required strength at lower basis weights than conventional approaches.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements composite materials using a softwood-hardwood furnish composition that optimizes strength-to-weight ratio. The specific combination (20-40% softwood, 60-80% hardwood) with differentiated fibrillation levels creates a composite structure that achieves adequate strength at reduced basis weight compared to conventional single-fiber-type papers.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12104327B2Tissues and paper towels incorporating surface enhanced pulp fibers and methods of making the same

Publication Date: 2024.10.01 DOMTAR PAPER COMPANY LLC(US)

AI summary

Paper products can comprise a first plurality of fibers that are hardwood fibers and a second plurality of fibers that include softwood fibers and surface enhanced pulp fibers (SEPF). The paper product can include one or more first fiber layers that comprise the first fibers, at least one of the first fiber layer(s) defining one of opposing upper and lower surfaces of the paper product, and one or more second fiber layers that comprise the second fibers. When a tissue, by weight, between 50% and 80% of the tissue's fibers can be the first fibers and at least 20% of the tissue's fibers can be the second fibers. The tissue's basis weight can be less than or equal to 21 gsm per ply.