Starch-Based Polymer Surface Size for Paper Strength
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Solution Overview
Problem
Existing paper and board production methods face challenges in enhancing strength properties, particularly compression strength and burst strength, when using increased amounts of inorganic mineral fillers and recycled fibers, which often result in cost inefficiencies and compromised product quality.
Innovation Solution
A water-soluble polymer composition is developed by polymerizing acrylamide and/or methacrylamide with unsaturated mono- or dicarboxylic acids in an aqueous medium containing degraded starch, creating a polymer network that improves dry strength properties when applied as a surface size, allowing for reduced usage or enhanced strength with existing amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the amount of inorganic mineral fillers and recycled fibres in the stock is increased to reduce costs, then cost efficiency is improved, but compression strength and burst strength are negatively affected
Solution Approach 1:
A polymer composition is introduced as an intermediary substance between the fibre-infiller matrix and the surface environment. This polymer acts as a binding agent that reinforces the surface structure, compensating for the strength reduction caused by high filler content. The polymer composition includes functional groups that interact with both the mineral fillers and fibres, creating a cohesive surface layer that restores compression and burst strength while allowing continued use of cost-effective high-filler formulations
2Strength
If synthetic polymers are used in surface size solutions to improve strength properties, then strength properties are improved, but viscosity increases making application difficult and costs increase
Solution Approach 1:
The chemical structure parameters of the polymer are specifically designed to achieve the desired strength enhancement while controlling molecular weight and chain architecture to maintain acceptable viscosity. By adjusting parameters such as polymer chain length, branching degree, and functional group density, the formulation achieves optimal balance between strength improvement and application characteristics, allowing conventional size press equipment to handle the solution effectively
Solution Approach 2:
The surface size solution employs a composite formulation combining polymer composition with starch and water. This composite approach leverages the reinforcing effect of the polymer while starch provides bulk and cost-effectiveness. The synergistic interaction between polymer and starch components delivers enhanced strength properties without the viscosity penalties associated with high concentrations of pure synthetic polymer, maintaining ease of application
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 polymer composition effectively increases the dry strength, burst strength, and bending stiffness of paper and board products, enabling cost-effective improvements while maintaining or reducing the amount of surface size composition needed, thus optimizing production efficiency and product quality.
Implementation Method 1
surface sizing can be used to increase hydrophobicity of the paper/board surface or to improve the strength properties of paper/board
Implementation Method 2
polymerizing in an aqueous polymerisation medium, which comprises degraded starch, at least following monomers acrylamide and/or methacrylamide, and >2 mol-% of at least one unsaturated mono- or dicarboxylic acid(s) or salts thereof
Data Source
AI summary
The invention relates to a water-soluble polymer composition obtained by polymerizing in an aqueous polymerisation medium, which comprises degraded starch, at least following monomers: acrylamide and/or methacrylamide, and >2 mol-% of at least one unsaturated mono- or dicarboxylic acid(s) or salts thereof. The polymer composition has an anionic net charge at pH 7 and a dry solids content of >5 weight-%. The invention relates also to the use of the polymer composition for surface sizing of paper, board or the like as well as to a surface size composition comprising it.