Polyvinylamine Polymer for Paper Drainage and Strength
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Solution Overview
Problem
The use of high molecular weight polyvinylamine polymers in papermaking can lead to overflocculation and decreased dewatering efficiency, resulting in foaming and reduced strength properties in paper and board products, particularly when using recycled fibers like OCC pulp.
Innovation Solution
A papermaking agent composition with a water-soluble polymer containing 21-30 mol-% vinylamine units and an average molecular weight of at least 1,000,000 Da is added to the fibre stock, optimizing drainage and retention while enhancing strength properties such as burst strength, short span compression, and tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high molecular weight polyvinylamine polymers are used to improve drainage and retention, then dewatering efficiency improves, but overflocculation occurs leading to foaming and decreased strength properties
Solution Approach 1:
The patent changes the chemical parameters of the polyvinylamine polymer by controlling the degree of hydrolysis to specifically 1-20 mol-% and molecular weight to at least 1 million, creating an optimal balance between drainage improvement and strength maintenance. This parameter optimization prevents overflocculation while achieving effective dewatering.
2Reliability
If polyvinylamine polymers are added to improve retention, then retention of formed web improves, but overcationisation occurs causing foaming and decreased dewatering effectivity
Solution Approach 1:
The patent optimizes the cationic charge density by controlling the degree of hydrolysis parameter, ensuring that sufficient retention is achieved without excessive cationisation that would cause foaming and dewatering problems. The specific range of 1-20 mol-% hydrolysis provides the right balance.
3Ease of manufacture
If cheaper recycled raw materials like OCC are used to reduce cost, then cost efficiency improves, but challenges in wet end retention and strength properties increase
Solution Approach 1:
The patent uses polyvinylamine polymer as an intermediary substance that bridges the challenges of using recycled OCC fibers. The polymer acts as a retention aid that binds to the recycled fibers, improving wet end retention and enabling the successful use of cost-effective recycled materials.
4Ease of manufacture
If filler content is increased to reduce basis weight and improve cost efficiency, then cost efficiency improves, but wet end retention challenges increase
Solution Approach 1:
The polyvinylamine polymer serves as a mediator that improves the interaction between filler particles and fibers in the wet end. By optimizing the polymer's molecular weight and hydrolysis degree, the patent enhances filler retention without compromising the economic benefits of increased filler content.
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 significantly improves drainage and retention in the wet-end of paper machines, minimizing overcationization issues and enhancing the strength properties of the final paper or board products, especially when using recycled fibers.
Implementation Method 1
polyvinylamine polymers having high molecular weight may be too reactive, which may lead to overflocculation
Implementation Method 2
polyvinylamine polymers having high molecular weight may be too reactive, which may lead to overflocculation
Data Source
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AI summary
The invention relates to a papermaking agent composition, preferably in powder form, which comprises a water-soluble polymer, which comprises 21 – 30 mol-% of vinylamine units and has an average molecular weight of at least 1 000 000 Da. The invention relates also to a method for treating of fibre stock in manufacture of paper, board or the like, where a thick fibre stock is obtained, it is diluted to a thin fibre stock having a consistency < 3 % by addition of water, and the thin fibre stock is drained and a continuous fibrous web is formed. The papermaking agent composition is added to the thick fibre stock or to the thin fibre.