Paper Auxiliaries for papermaking industry
Product Details
Just as textile auxiliaries are the "seasoning" of the textile industry, paper auxiliaries (or papermaking chemicals) are the indispensable "soul" of the papermaking process. They permeate the entire process from pulping to papermaking, not only determining the smooth progress of production but also endowing paper with a myriad of properties, from ordinary writing paper to functional packaging paper and specialty paper.
Let's examine the key roles of these "unsung heroes" in the papermaking process:
Application by Production Process
1.Pulping Auxiliaries: Optimizing from the Source
This is the first step in papermaking. Auxiliaries are mainly used to treat raw material fibers, improving pulping efficiency and pulp quality.
Cooking Auxiliaries: Such as anthraquinone, which accelerates the penetration of chemicals, making it easier for wood chips or straw chips to separate into fibers, saving energy and time.
Waste Paper Deinking Agents: Composed of a variety of surfactants, these are responsible for peeling and dispersing printing ink particles from the fibers during waste paper recycling, giving waste paper a "new lease on life."
Bleaching Auxiliaries: Used in conjunction with bleaching agents such as hydrogen peroxide to protect fibers while improving whiteness.
2.Papermaking Additives: Controlling the Process and Imparting Basic Properties
This is the most crucial and diverse aspect of additive application, mainly divided into two categories: process additives and functional additives.
Process Additives: Ensuring Stable and Efficient Production
Retention and Filtration Aids: Such as cationic polyacrylamide (CPAM) and cationic starch. They act like a "molecular network," "capturing" fine fibers and fillers onto the paper while accelerating filtration and improving production efficiency.
Defoamers: Used to eliminate air bubbles generated during pulp circulation, preventing paper defects such as pinholes.
Preservatives/Bactericides: Prevent the formation of rotten pulp in the pulp and white water systems, avoiding paper breaks and off-odors.
Resin Barrier Control Agents: Prevent the precipitation and adhesion of natural resins from wood onto equipment, ensuring continuous production.
Functional Additives: Building the Basic Skeleton of Paper
Internal Sizing Agents: Impart water resistance to paper, preventing ink bleeding during writing. Rosin sizing is commonly used in acidic papermaking, while alkyl ketone dimers (AKD) are more common in neutral/alkaline papermaking.
Strengthening Agents: Divided into dry strength agents and wet strength agents. Dry strength agents (such as cationic starch and polyacrylamide) enhance the bonding force between fibers, improving the tensile strength and folding endurance of paper; wet strength agents (such as polyamide epichlorohydrin resin) allow paper to maintain a certain strength when wet or soaked in water, such as kitchen paper towels and map paper.
Softening Agents: Improve the feel of paper, making household paper (such as facial tissues) softer and more skin-friendly.
3.Coating Processing Additives: Creating a Perfect Surface
For coated paper and magazine paper requiring high-quality printing, coating is a crucial step, and additives are responsible for formulating the "coating."
Pigments and Dispersants: Pigments (such as kaolin and calcium carbonate) determine the whiteness and gloss of the coating, while dispersants (such as sodium polyacrylate) ensure that pigment particles are evenly dispersed in water and do not clump together.
Adhesives: Bond pigment particles together and firmly adhere to the paper surface, preventing dusting.
Water Repellents: Improve the water resistance of the coating, ensuring that it is not damaged by dampening water during high-speed printing.
Lubricants: Improve the flowability of the coating and the lubrication of the doctor blade coating, resulting in a smoother coating.
4.Other Additives
Water Treatment Chemicals: The papermaking process generates a large amount of wastewater, requiring the use of flocculants such as polyaluminum chloride and polyacrylamide for purification to achieve compliant discharge or recycling.
Key Application Points
System Matching: Papermaking is a complex wet-end chemical system. When adding paper auxiliaries, the interactions of factors such as ionicity (cationic/anionic/nonionic) and pH value must be considered to achieve optimal results.
Environmental trends: With increasing environmental protection requirements, the development of chlorine-free bleaching, bio-based, and biodegradable "green" paper auxiliaries, as well as special paper auxiliaries for waste paper recycling, are the current development priorities.