NCC-Polymer Surface Coating for Paper Strength and Retention

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Solution Overview

Problem

The papermaking process faces challenges in simultaneously enhancing drainage retention, wet strength, and dry strength while maintaining compatibility with other additives and avoiding degradation of the paper product's attributes.

Innovation Solution

The method involves adding a nano-crystalline cellulose (NCC)-polymer, comprising a polymer chain bonded to an NCC core, which can be distributed on the surface of the paper substrate using a size press, incorporating monomers such as vinyl acetate and acrylic acid, to improve dry strength and surface strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If retention aids such as polymers flocculants and silica based microparticles are added to the slurry to facilitate drainage retention, then drainage retention is improved, but they may interfere with or degrade the effectiveness of other additives present in the resulting paper product

Engineering Contradiction:

Improvedrainage retentionVSAvoideffectiveness of other additives

Core Design Contradiction:

Loss of substanceVSReliability

Solution Approach 1:

The patent uses cationic starch as an intermediary retention aid that mediates between the need for drainage retention and the compatibility with other additives. The cationic starch selectively binds to anionic sites on fibers and fillers, providing retention without the harsh effects of polymer flocculants, thereby maintaining the effectiveness of other papermaking additives.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter of retention aid selection from conventional polymer flocculants and silica microparticles to cationic starch-based retention aids. This parameter change allows for improved drainage retention while maintaining compatibility with other additives, as cationic starch operates through different mechanisms that are less interfering with other papermaking chemicals.

Inventive Principle:

Principle #35Parameter changes

2Strength

If dry strength agents are added to the slurry to increase the strength properties of the resulting sheet, then dry strength is improved, but they must allow for free drainage of water and not interfere with other additives

Engineering Contradiction:

Improvedry strengthVSAvoidfree drainage of water

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent segments the strength enhancement function into two parts: (1) cationic starch applied during the wet end for drainage and initial strength, and (2) dry strength agents applied separately at the dry end. This segmentation allows each component to perform its specific function without interfering with the other, maintaining both free drainage and dry strength improvement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies cationic starch as a preliminary action during the wet end of the papermaking process to establish initial strength and facilitate drainage before the sheet is fully formed. This preliminary strengthening allows subsequent dry strength agents to work more effectively without compromising drainage efficiency.

Inventive Principle:

Principle #10Preliminary action

3Strength

If surface strength agents are applied as coatings over the formed paper sheet at the size press to increase resistance to abrasive forces, then surface strength is improved, but they must be compatible with other items present in coatings and not impair the flexibility of the resulting paper product

Engineering Contradiction:

Improvesurface strengthVSAvoidcompatibility with other coating items and flexibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent employs composite coating formulations at the size press that combine surface strength agents with compatibility modifiers and flexibility enhancers. This composite approach allows the coating to simultaneously provide surface strength, maintain compatibility with sizing agents and optical brighteners, and preserve the flexibility of the paper product.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies surface strength agents as a localized coating only at the size press stage, rather than throughout the entire papermaking process. This local application allows for targeted surface strengthening while minimizing the impact on the bulk properties and flexibility of the paper, and enables better compatibility control with other coating components.

Inventive Principle:

Principle #3Local quality

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 significantly improves drainage retention, wet strength, and dry strength of the paper substrate, reducing material waste and costs, while maintaining the flexibility and optical properties of the paper.

Implementation Method 1

adding the NCC-polymer to a paper substrate in the dry end of a papermaking process, wherein the NCC-polymer is substantially distributed on the surface of the substrate

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS10132040B2Use of nanocrystaline cellulose and polymer grafted nanocrystaline cellulose for increasing retention in papermaking process

Publication Date: 2018.11.20 ECOLAB USA INC

AI summary

Methods and compositions for improving the characteristics of paper substrates are disclosed. The methods involve adding to a paper substrate an NCC-polymer. NCC-polymers have unique chemical properties which result in improvements in wet strength, dry strength and drainage retention properties of the paper substrates.