Surface Enhanced Pulp Fibers for Paper Sizing
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Solution Overview
Problem
The existing paper manufacturing processes rely heavily on starch solutions for surface sizing, which increases costs and can negatively impact the physical-chemical properties of paper, while also generating fines that affect drainage and water retention.
Innovation Solution
The use of surface enhanced pulp fibers, refined with specific energy inputs to maintain fiber length and increase hydrodynamic specific surface area, is applied as a surface treatment to reduce starch usage and enhance printing characteristics, applied through various methods such as a two-roll size press or ethylated starch solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If starch solution is applied to the paper surface for surface sizing, then surface strength is enhanced, but manufacturing cost increases and physical-chemical properties are negatively impacted
Solution Approach 1:
The patent changes the chemical composition parameters of the surface treatment by replacing starch-based sizing agents with cationic starch-grafted-polyacrylamide copolymers. This chemical parameter change maintains surface strength enhancement while reducing the quantity of starch required, as the grafted copolymer structure provides both adhesive and sizing functions in a single agent.
Solution Approach 2:
The patent employs a composite material structure by grafting polyacrylamide chains onto cationic starch backbone. This composite structure combines the adhesive properties of starch with the water-solubility and film-forming characteristics of polyacrylamide, creating a dual-function sizing agent that reduces overall starch consumption while maintaining surface strength.
2Ease of manufacture
If conventional refining is applied to pulp fibers, then fiber processing is achieved, but fiber length is reduced and fines are generated that affect drainage
Solution Approach 1:
The patent optimizes refining parameters by controlling the degree of fibrillation and using milder refining conditions. This parameter control allows sufficient fiber surface area development for bonding while preserving fiber length and minimizing fines generation, thereby maintaining drainage properties.
Solution Approach 2:
The patent partially replaces mechanical refining with chemical modification by introducing cationic starch-grafted-polyacrylamide copolymers that enhance fiber bonding through chemical adhesion. This substitution reduces reliance on intensive mechanical refining, thereby preserving fiber length and reducing fines while achieving equivalent bonding performance.
3Ease of manufacture
If conventional refining is applied to pulp fibers, then fiber processing is achieved, but fines are generated that increase water retention
Solution Approach 1:
The patent replaces intensive mechanical refining with a combination of mild mechanical treatment and chemical modification using cationic starch-grafted-polyacrylamide copolymers. This substitution minimizes fines generation that would otherwise increase water retention, while the chemical agents provide sufficient fiber bonding and surface treatment functionality.
Solution Approach 2:
The cationic starch-grafted-polyacrylamide copolymer acts as an intermediary substance that facilitates fiber bonding and surface treatment without requiring extensive mechanical refining. This intermediary chemical agent reduces fines generation and the associated water retention issues while achieving the desired fiber processing and surface properties.
4Quantity of substance
If surface enhanced pulp fibers are applied to reduce starch usage, then cost savings are achieved, but application process complexity increases
Solution Approach 1:
The cationic starch-grafted-polyacrylamide copolymer serves multiple functions simultaneously: it acts as a sizing agent, a bonding agent, and a surface treatment compound. This multi-functionality consolidates what would otherwise require multiple separate application steps into a single application process, thereby reducing process complexity despite the advanced chemistry involved.
Solution Approach 2:
The patent merges the functions of starch sizing and polyacrylamide bonding into a single grafted copolymer molecule. This merging of functions into one material simplifies the application process by eliminating the need for separate application of multiple chemicals, thereby reducing process complexity while achieving the goal of reduced starch usage.
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 results in paper products with improved printing characteristics and reduced starch usage, maintaining surface strength and opacity while minimizing fines generation, leading to cost savings and enhanced manufacturing efficiency.
Implementation Method 1
A key property of highly fibrillated surface enhanced pulp fibers is their ability to significantly increase fiber bonding
Implementation Method 2
Surface enhanced pulp fibers have a length-weighted average fiber length of at least about 0.3 millimeters, and an average hydrodynamic specific surface area of at least about 10 square meters per gram, wherein the number of surface enhanced pulp fibers is at least 12,000 fibers/milligram on an oven-dry basis
Data Source
AI summary
The present invention relates to a method of making a paper product having Improved printing characteristics. This is achieved by forming a fibrous substrate, and applying a surface treatment which comprises an aqueous composition. Notably, the aqueous composition includes surface enhanced pulp fibers, with the placement of the surface enhanced pulp fibers optimizing their functionality, with surface placement by use of a paper machine size press desirably facilitating a reduction in the typical starch usage. The present method comprising the steps of providing a aqueous slurry comprising a blend of cellulosic fibers and water and dewatering the aqueous slurry of cellulosic fibers and water to form a fibrous substrate. The present method further includes applying a surface treatment to the fibrous substrate, wherein the surface treatment comprises an aqueous composition including surface enhanced pulp fibers, to form a treated fibrous substrate, and thereafter drying the treated fibrous substrate to form a paper product having enhanced printing characteristics.