Boronic Acid Polymers for Alkaline Paper Wet Strength
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Solution Overview
Problem
Current papermaking technologies face challenges in enhancing paper wet web strength and wet strength, particularly under alkaline conditions, as existing additives like chitosan and cationic aldehyde starch are ineffective at neutral or alkaline pH, and commercial wet-strength resins are not environmentally friendly and unstable in aqueous conditions.
Innovation Solution
Development of novel polymer derivatives containing boronic acid that form covalent bonds with cellulose fibers under a wide pH range, including alkaline conditions, to improve both wet web strength and wet strength, using polymeric compounds such as boronic acid-containing polyvinylamine and hydroxypropyl guar complexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chitosan or cationic aldehyde starch is used to enhance wet web tensile strength by cross-linking fibers, then wet web strength is improved, but the additives are impeded at alkaline conditions which are preferred for modern papermaking
Solution Approach 1:
The patent changes the chemical parameters of the additive by using boronic acid-containing polymers instead of traditional chitosan or cationic aldehyde starch. Boronic acid groups can form covalent bonds with cis-diols on cellulose fibers under alkaline conditions, allowing the additive to function effectively at the preferred alkaline pH levels (pH 9-11) of modern papermaking processes while maintaining wet web tensile strength enhancement.
Solution Approach 2:
The invention employs composite polymer structures containing boronic acid groups combined with polymeric backbones (such as polyvinylamine, polyacrylamide, or polysaccharide derivatives). This composite approach allows the material to exhibit both the fiber-crosslinking capability needed for strength enhancement and the chemical stability required for alkaline condition compatibility.
2Strength
If commercial wet-strength resins based on polyamine-epichlorohydrin chemistry are used under neutral and alkaline conditions, then wet strength is improved, but they are not environmentally friendly and not stable under aqueous conditions
Solution Approach 1:
The patent employs boronic acid-containing polymers that form reversible covalent bonds with cellulose fibers through boronate ester linkages. These bonds are stable under aqueous conditions during the papermaking process but can be controlled to provide temporary wet strength enhancement without the environmental persistence issues of traditional polyamine-epichlorohydrin resins. The additives are water-soluble and biodegradable, addressing environmental concerns while maintaining functional stability.
Solution Approach 2:
The invention changes the chemical mechanism from irreversible cross-linking (polyamine-epichlorohydrin) to reversible boronate ester formation. This parameter change allows the additive to maintain stability under aqueous conditions during processing while providing controllable wet strength enhancement, and the products can be tuned for different levels of permanence and environmental friendliness.
3Strength
If urea-formaldehyde resins or melamine-formaldehyde resins are used under acidic papermaking conditions, then wet strength is improved, but they cannot be used under neutral and alkaline conditions
Solution Approach 1:
The patent develops boronic acid-containing polymers that function universally across a wide pH range (pH 3-11), replacing the need for different resin systems for acidic versus alkaline conditions. The boronic acid groups maintain their ability to form covalent bonds with cellulose fibers across this broad pH range, making the additive universally applicable to both traditional acidic and modern alkaline papermaking processes.
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 boronic acid-containing polymers effectively increase paper wet web strength and wet strength, maintaining stability across a broad pH range, thereby enhancing paper production efficiency and environmental sustainability.
Implementation Method 1
Under alkaline conditions, boronic acid becomes sp3 hybridized (—B(OH)3) and forms esters (i.e. covalent bond) with cis diols on carbohydrates and polyols.
Data Source
AI summary
Polymeric compounds of formula I comprising boronic acid are provided. These polymeric compounds are prepared either by grafting boronic acid containing compounds (e.g. 4-carboxyphenylboronic acid) to hydrolysed poly(N-vinylformamide) or hydrolysing copolymer(s) obtained by copolymerizing vinyl group containing boronic acid monomers (e.g. -vinylphenyl boronic acid) and N-vinylformamide. These polymeric compounds are used in increasing the wet strength of paper in paper-making processes. Formula (I).