FWA Formulation Brightness and Yellowing in Papermaking
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Solution Overview
Problem
Conventional optical brightening agents (OBA) face limitations in brightness gain and yellowing due to overdosing, especially in paper products with significant mechanical pulp content, and existing fluorescent whitening agents (FWA) suffer from low solubility and retention issues in papermaking processes.
Innovation Solution
The combination of FWA formulation FB #351 and FB #71, which have different molecular structures and improved solubility, is used in the wet-end papermaking process to achieve higher brightness and retention rates without yellowing, utilizing their unique light re-emission properties and interactions with paper fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional FWA is overdosed to increase brightness, then brightness gain is improved, but yellowing occurs due to the natural appearance of conventional FWA
Solution Approach 1:
The patent changes the molecular structure parameters of the FWA from conventional types to new generation FB #351 and FB 71, which have different emission characteristics. This structural parameter change allows achieving higher brightness without the yellowing effect that plagues conventional FWA overdosing
Solution Approach 2:
The patent creates a composite FWA formulation combining FB #351 and FB 71 in specific ratios (30:70 to 70:30). This composite approach leverages the complementary properties of both dyes to achieve superior brightness enhancement without yellowing, overcoming the limitations of single-component conventional FWAs
2Illumination intensity
If FWA formulation is used to achieve high brightness, then brightness gain is improved, but solubility and retention issues occur in papermaking processes
Solution Approach 1:
The patent modifies the chemical parameters of the FWA by selecting FB #351 and FB 71 which possess superior solubility characteristics compared to conventional FWAs. This parameter change ensures reliable dissolution and retention in the papermaking process while maintaining high brightness performance
3Illumination intensity
If FWA is used in mechanical pulp papermaking, then brightness is improved, but brightness reversion occurs due to limitations in brightness gain
Solution Approach 1:
The patent changes the FWA molecular structure to FB #351 and FB 71 which exhibit superior stability characteristics. These new generation dyes maintain their brightness-enhancing properties over time in mechanical pulp papermaking applications, preventing the brightness reversion that occurs with conventional FWAs
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
This approach allows for increased brightness and retention rates at lower costs, overcoming the limitations of conventional OBAs and FWAs by maintaining high ISO brightness values and preventing brightness reversion, thus expanding market applications and reducing costs.
Implementation Method 1
Optical brightening agents (OBA's) or fluorescent whitening agent (FWA's) have chemical properties that absorb light in the ultraviolet region (340-370 nm) and then re-emitting it back into the visible spectrum
Data Source
AI summary
A new fluorescent whitening agent (FWA) formulation containing 0.1%-99.9% fluorescent brightener #351 (FB #351) 4,4″-bis(2-sulfostyryl)biphenyl disodium salt (CAS #27344-41-8) and 0.1%-99.9% fluorescent brightener #71 (FB #71) 4,4′-bis[4-anilino-6-morpholino-1,3,5-triazin-2-yl]amino-2,2′-stilbene disodium salt (CAS #16090-02-1) is used on the wet-end papermaking process and coating papermaking process to increase the brightness of paper.