Softener Composition with Acidic Material for Paper Wet Strength
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Solution Overview
Problem
Paper products made from untreated cellulose fibers lose strength when wet, and existing wet strength resins like aldehyde functionalized polymers are ineffective at high pH levels, requiring acidic adjustments that are costly and pose safety concerns.
Innovation Solution
A softener composition combining an acidic material with aldehyde functionalized polymers, such as glyoxylated polyacrylamide, to enhance wet strength without affecting dry strength, while controlling pH and reducing viscosity, allowing for higher concentration emulsions and improved handling costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aldehyde functionalized polymers are used to enhance wet strength, then wet strength is improved, but effectiveness is lost at high pH levels
Solution Approach 1:
The invention changes the pH parameter of the aqueous solution to acidic or neutral conditions (pH ≤ 7), which enables the aldehyde functionalized polymer to effectively crosslink with cellulose fibers and form covalent bonds, thereby achieving high wet strength in acidic and neutral environments
2Reliability
If strong acids are added to lower pH for polymer effectiveness, then polymer performance is improved, but corrosion and safety issues worsen
Solution Approach 1:
The invention uses food-grade citric acid, a safe and biodegradable organic acid, instead of strong mineral acids. This approach eliminates corrosion and safety concerns while maintaining the necessary acidic conditions for polymer effectiveness, as citric acid is non-corrosive and safe for paper contact
Solution Approach 2:
The invention changes from using strong mineral acids to using weak organic acids (citric acid), which provides the necessary pH reduction without introducing harmful corrosion and safety factors, enabling effective polymer performance in a safe manner
3Reliability
If acid is added to pulp slurry to lower pH, then polymer effectiveness is improved, but precipitation and deposition of chemicals worsen
Solution Approach 1:
The invention changes from using strong acids that cause immediate precipitation to using weak organic acids (citric acid) that gradually lower pH without causing precipitation or deposition of dissolved and suspended chemicals, thereby maintaining polymer effectiveness without generating harmful precipitation
4Ease of operation
If softener is added to improve softness, then softness is improved, but wet strength performance deteriorates
Solution Approach 1:
The invention applies the softener composition after the aldehyde functionalized polymer has already crosslinked the cellulose fibers to form covalent bonds and establish wet strength. This preliminary action of strength formation before softening prevents the softener from disrupting the crosslinked network, thereby maintaining both softness and wet strength
Solution Approach 2:
The invention separates the softening function from the strength-forming function by using a softener composition containing citric acid that provides softness without interfering with the previously formed covalent crosslinks, allowing independent optimization of both softness and wet strength
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 softener composition maintains high wet strength performance while minimizing dry strength loss, reduces the need for pH adjustments, and lowers shipping and handling costs by enabling higher concentration emulsions, thus enhancing paper product properties effectively.
Implementation Method 1
the aldehyde functionalized polymer is believed to form covalent bonds with cellulose to increase paper dry strength and wet strength
Implementation Method 2
Papermakers often add strong acids to the pulp slurry during the papermaking process to enhance the performance of the aldehyde functionalized polymer
Data Source
AI summary
A softener composition for use in the manufacture of paper includes a softener and an acidic material, wherein the softener composition has a relative acidity (RA) value of more than 0.05.