Multiply Containerboard Structure for Adhesion and Moisture Resistance
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Solution Overview
Problem
Existing corrugated board production faces challenges with adhesion issues between liners and fluting, leading to delamination, washboarding, and curl, while also struggling with moisture resistance and mechanical strength, particularly in containerboard made from neutral sulfite semi-chemical (NSSC) pulp, which requires high chemical usage and increased grammage to address these issues.
Innovation Solution
A multiply containerboard structure comprising outer plies predominantly of NSSC pulp and an intermediate ply with unbleached kraft pulp and a cellulose-based strength enhancement agent, optimizing adhesion and moisture resistance without compromising dewatering speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is added to ensure sufficient adhesion between liner and fluting, then adhesion is improved, but washboarding and curl occur
Solution Approach 1:
The patent applies local quality by creating an intermediate ply with specific properties (higher chemical pulp content, higher strength enhancement agent content) positioned between the outer plies. This localized modification optimizes adhesion at the critical interface between liner and fluting without affecting the overall board structure, preventing washboarding and curl while maintaining sufficient adhesion.
Solution Approach 2:
The patent uses composite materials by combining different pulp types (chemical pulp and mechanical pulp) and adding strength enhancement agents to create an intermediate ply with optimized properties. This composite structure provides the right balance of adhesion, stiffness, and moisture resistance without causing washboarding or curl.
2Ease of manufacture
If NSSC pulp is used to reduce costs and increase yield, then manufacturing cost is reduced, but adhesion and moisture resistance deteriorate
Solution Approach 1:
The patent applies composite materials by creating a three-ply structure where outer plies use cost-effective NSSC pulp while the intermediate ply uses a composite of chemical pulp and strength enhancement agents. This composite approach maintains high NSSC content (60-90%) for cost efficiency while the intermediate ply provides the necessary adhesion and moisture resistance properties.
Solution Approach 2:
The patent applies local quality by concentrating the expensive chemical pulp and strength enhancement agents only in the intermediate ply (10-40% of total board thickness) rather than throughout the entire board. This localized modification maintains reliability at critical interfaces while preserving cost benefits in the outer plies.
3Strength
If chemical pulp is added to improve strength and mechanical properties, then burst strength is improved, but dewatering speed reduces
Solution Approach 1:
The patent applies local quality by adding chemical pulp and strength enhancement agents only to the intermediate ply rather than distributing them throughout the entire board. This localized concentration provides maximum burst strength improvement at the critical load-bearing interface while minimizing the negative impact on dewatering speed in the outer plies.
Solution Approach 2:
The patent applies partial action by adding chemical pulp and strength enhancement agents only to the intermediate ply (partial board structure) rather than the entire board. This partial modification achieves sufficient burst strength improvement without the excessive chemical pulp content that would severely impact dewatering speed across the whole board.
4Object-affected harmful factors
If grammage is increased to improve moisture resistance, then moisture resistance is improved, but chemical consumption increases
Solution Approach 1:
The patent applies local quality by concentrating moisture-resistant properties in the intermediate ply through targeted addition of chemical pulp and strength enhancement agents. This localized modification provides effective moisture resistance at the critical interface without requiring increased grammage or chemical consumption across the entire board structure.
Data Source
AI summary
The present invention relates to a multiply containerboard for use in corrugated board, said multiply containerboard comprising: a first outer ply, a second outer ply, and at least one intermediate ply sandwiched between the first and second outer ply, wherein said first and second outer ply comprise at least 70 wt % neutral sulfite semi chemical (NSSC) pulp based on dry weight, and wherein said intermediate ply comprises at least 30 wt % unbleached kraft pulp based on dry weight and at least one cellulose based strength enhancement agent, and wherein said intermediate ply comprises less than 30 wt % NSSC pulp based on dry weight.