Cationic Surface Sizing for Neutral Newsprint Water Resistance
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Solution Overview
Problem
Newsprint for offset printing, particularly neutral newsprint, faces challenges in achieving sufficient water absorption resistance due to low aluminum sulfate addition ratios, leading to increased color registration errors and poor image quality.
Innovation Solution
A surface treating agent comprising a cationic surface sizing agent, formed by copolymerizing styrene monomers with cationic monomers and hydrophobic monomers, is applied to newsprint base paper, enhancing water absorption resistance through external addition, which is particularly effective for neutral newsprint with low aluminum sulfate content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional surface sizing agents (copolymer of carboxyl group monomer and styrene monomer) are used for neutral newsprint with low aluminum sulfate content, then the paper can be manufactured with reduced aluminum sulfate addition, but the water absorption resistance is significantly decreased
Solution Approach 1:
The patent changes the chemical parameters of the surface sizing agent by introducing cationic monomers (containing amino groups) into the copolymer structure. This modifies the interaction mechanism with aluminum components, enabling effective water absorption resistance even at low aluminum sulfate addition ratios in neutral papermaking processes.
Solution Approach 2:
The patent uses a composite surface sizing agent comprising multiple monomer components (styrene monomer, cationic monomer with amino group, and hydrophobic monomer). This composite structure creates synergistic effects where the cationic groups interact with aluminum components while the hydrophobic portions provide water resistance, overcoming the limitation of conventional single-component sizing agents.
2Reliability
If the amount of conventional surface sizing agent is increased to compensate for reduced aluminum sulfate content, then water absorption resistance may be partially restored, but the paper strength and surface properties deteriorate
Solution Approach 1:
The patent optimizes the compositional parameters of the surface sizing agent by controlling the ratio of cationic monomer to other monomers. This parameter optimization allows achieving effective water absorption resistance at lower dosages, thereby maintaining paper strength while providing sufficient sizing performance.
3Ease of manufacture
If neutral papermaking is adopted to reduce aluminum sulfate addition, then environmental and quality improvements are achieved, but the effectiveness of conventional surface sizing agents is reduced
Solution Approach 1:
The patent adapts the surface sizing agent parameters to match the neutral papermaking process by incorporating cationic monomers that can effectively interact with the reduced aluminum sulfate content. This parameter adaptation ensures that conventional sizing agents remain effective even under neutral papermaking conditions.
Solution Approach 2:
The cationic monomer units in the surface sizing agent act as intermediaries that bridge the gap between the reduced aluminum sulfate content and the required water absorption resistance. The cationic groups mediate the interaction with remaining aluminum components while the hydrophobic portions ensure adequate sizing performance.
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 provides newsprint with improved water absorption resistance, reducing fiber swelling and color registration errors, resulting in clear and accurate printed images.
Implementation Method 1
the hydrophobic styrene monomer part is positioned on the surface of the paper, thereby providing water absorption resistance to the newsprint
Data Source
AI summary
Newsprint for offset printing having sufficient water absorption resistance to provide a clear printing image with less color registration problems upon offset printing is manufactured by coating base paper, to which aluminum sulfate (a 50% by weight Al2O3.14H2O product) is added at a ratio of less than 3.0% by weight upon paper making, with a surface treating agent mainly comprised of (A) a water-soluble macromolecular substance selected from starches, PVAs, polyacrylamides, and cellulose derivatives, (B) a copolymer obtained by the copolymerization of a styrene monomer and a cationic monomer, a water-soluble copolymer obtained by the copolymerization of a styrene monomer, a cat ionic monomer and a hydrophobic monomer, or a water-soluble copolymer obtained by treating one of these copolymers in which a tertiary amine-containing vinyl monomer is used as a cationic monomer, with a quaternizing agent.