In today’s paper and tissue manufacturing processes, some helpful chemicals such as fillers, sizing additives, defoamers, thickeners, retention aids, and welter dry strength resins are commonly used. Wet-strength resin chemicals are introduced to the stock for producing paper or tissue.
Paper often retains 3 to 5 percent of its dry strength after being thoroughly wet, which is most usually called to be the support of fiber-to-fiber friction. Wet strength resin chemicals give the paper 10 to 50 percent of its dry strength when wet. However, this property is often used in other paper and paperboard categories, too, such as kitchen towel paper, coffee filters, sanitary towels, and some packages.
However, this strength is usually measured as a wettear or wettensile, and is also better represented as the portion of ‘tear maintained or dry tensile’ (“wetover dry”).
The most widely recommended wet strength resin chemical by suppliers are PAE, DAS, UF, MF, and PEI. Although if the wetstrength of either the paper grade is far too high, there would be a significant problem before and after the re-pulping process. It is, therefore, vital to learn how to effectively de-gradate paper via high wetstrength.
Wet Strength Resin High-Efficiency Technology Breakthrough
For the last several years, wetresins have mostly enabled paper manufacturers to take the paper to that application usage where it was never thought to be used before. Such as, now you can find it as a substitute for coolers (beverage cases), as a substitute for fabric (paper towels), and as a substitute for plastic (lawn bags).
Amid from other wetstrength resin, Polyamide Epichlorohydrin (PAE) has been effectively used in paper production for many years, which has replaced the older techniques to retain paper strength when the paper, board, towel, tissue, or specialized content is wetted. As technology has evolved, significant changes in wet strength resin chemicals quality in the industry have always been a question of fine-tuning.
A Big Evolution In Wet Strength Resins Usage
Over the decades, PAE’s wet strength resin chemical has gradually evolved from low-efficiency, low solids resins to today’s 20-30% solids, highly effective products. Moreover, this is made possible with research efforts that brought incredible results with small changes in solids, cost, stability, and performance.
This R&D initiative has subsequently succeeded because of the mushrooming technology that focused on a variety of advances that made it go beyond the gradual improvement in wet resin technologies commonly seen in the industry.
All such innovations have been merged into a new variant of PAE wet strength resin chemicals for paper, operationally referred to it as the Ultra 25 Amres ® wetstrength resin.
This technique is gained from the use of new raw materials and innovative production techniques, which have ended in significant increase in output and quality relative to even the greatest substitute wetstrength resin.
Why Wet Strength Resins Are So Important For Papermaking?
Worldwide use of wet-strength resins is reported to be between 400000 and 500000 tons each year, with a value of approximately US$ 470 million. For instance, wet-strength resins are an essential category amid papermaking chemicals.
However, wet strength resin chemical induces a significant improvement in the physical properties of the paper. Its resilience in the dry condition and its ability to crumble while wet, simply enhances the consistency of the paper.
They are thus only used for a portion of the overall production of paper, but that still corresponds to 4-5 percent of all paper manufactured or 10 million tons each year.
Resins are the most widely used agents. There are two methods to improve the wetstrength of paper.
- One is ‘protective mechanism’. This ensures that the resins shape a shielding network all over the fibers, which then keeps the bonding from splitting apart.
- Another is ‘enhancement mechanism,’ which augment the strength of the fiber network.
So this is how the entire process of wet strength resins goes on during paper manufacturing.
Frequently Asked Question
The wet strength of paper refers to its ability to maintain its structural integrity and strength when it becomes wet or comes into contact with moisture. It is an important property for various paper products, such as tissues, towels, and packaging materials, to ensure they don’t easily disintegrate or lose their strength when exposed to water. Wet strength is typically achieved through the addition of chemicals or treatments during the papermaking process.
Wet strength chemicals are substances added during the papermaking process to enhance a paper’s resistance to moisture and maintain its strength when wet. Common wet strength chemicals include:
Polyamideamine Epichlorohydrin (PAE): PAE resins are widely used in papermaking to provide wet strength. They cross-link with cellulose fibers in the paper, forming a strong bond that is stable even when wet.
Melamine Formaldehyde: Melamine-formaldehyde resins are used to impart wet strength to paper. These resins create cross-links with cellulose fibers, improving the paper’s ability to withstand moisture.
Polyacrylamide: Polyacrylamide-based polymers can be added to the paper pulp to improve wet strength. They form a three-dimensional network within the paper structure, enhancing its resistance to water.
Polyethylene Glycol (PEG): PEG can be used as a wet strength additive. It helps improve the paper’s resistance to water and moisture.
Starch: Modified starches can be used to enhance wet strength in paper. Starch molecules can form hydrogen bonds with cellulose fibers, providing some degree of wet strength.
Cationic Polymers: Various cationic polymers, such as polyvinylamine, are used as wet strength agents. They interact with the negatively charged cellulose fibers in paper and enhance its wet strength.
The choice of wet strength chemical depends on the specific requirements of the paper product and the manufacturing process. Manufacturers often tailor the formulation to achieve the desired level of wet strength while maintaining other paper properties like flexibility and printability.
Increasing the wet strength of paper involves modifying the papermaking process by adding specific chemicals or treatments that enhance its ability to withstand moisture. Here are steps to increase the wet strength of paper:
Select Appropriate Fibers: Choose cellulose fibers that have inherent wet strength properties, such as hardwood pulps, which generally have better wet strength than softwood pulps.
Use Wet Strength Additives: Incorporate wet strength chemicals into the paper pulp during the papermaking process. Common additives include Polyamideamine Epichlorohydrin (PAE), melamine formaldehyde, polyacrylamide, and cationic polymers. These additives create bonds or cross-links within the paper structure, making it more resistant to water.
Optimize Additive Concentration: Carefully control the amount and concentration of wet strength additives. Too much or too little can affect the paper’s properties. Optimization ensures the desired level of wet strength is achieved.
Modify Paper Formation: Adjust the paper formation process to promote even distribution of fibers and wet strength additives. This can involve refining the pulp, adjusting the pH of the pulp, or altering the order of additive addition during papermaking.
Control Drying Conditions: Proper drying is crucial to set the wet strength. Ensure that the paper is dried evenly and not exposed to extreme heat, which can degrade the wet strength additives.
Test and Quality Control: Implement quality control measures to assess and verify the wet strength of the paper. This may involve conducting wet tensile strength tests, Cobb tests (to measure water absorption), or other relevant tests to ensure the desired wet strength properties are met.
Consider Coating: Depending on the application, you may apply a water-resistant coating to the paper surface. Coatings can further enhance the paper’s ability to repel moisture.
Evaluate End-Use Requirements: Tailor the wet strength treatment to the specific requirements of the end-use application. For instance, tissue paper may require different wet strength properties compared to packaging board.
Adopt Advanced Technologies: Stay updated with advancements in papermaking technology and wet strength additives to continually improve the wet strength of your paper products.
It’s important to note that increasing wet strength may affect other properties of the paper, such as its flexibility, printability, and cost. Therefore, a balance must be struck to meet the desired wet strength while maintaining the paper’s suitability for its intended purpose. Manufacturers often conduct extensive research and testing to achieve the optimal combination of properties.
Wet strength paper is designed to maintain its structural integrity and strength when it becomes wet or comes into contact with moisture. It possesses several key properties that distinguish it from regular paper:
Resistance to Moisture: The most prominent property of wet strength paper is its resistance to moisture. It can withstand exposure to water or other liquids without significant loss of strength or disintegration.
Wet Tensile Strength: Wet strength paper exhibits a higher tensile strength when wet compared to regular paper. Tensile strength measures the paper’s ability to withstand stretching or pulling forces, and wet strength paper maintains this property even in a wet environment.
Durability: Wet strength paper is more durable when exposed to moisture, making it suitable for applications where regular paper would weaken or tear when wet.
Dimensional Stability: It maintains its dimensions better when wet, reducing distortion, curling, or warping that might occur with standard paper.
Resistant to Softening: Wet strength paper does not become excessively soft or mushy when wet, which can be important for applications like food packaging where maintaining the integrity of the packaging material is crucial.
Printability: Wet strength paper can be designed to retain its print quality when exposed to moisture, making it suitable for labels, packaging with printed information, and other applications requiring printed content.
Absorption Properties: Depending on the specific formulation and application, wet strength paper can be designed to have controlled water absorption properties. Some wet strength papers are designed to resist water absorption to a certain extent.
Chemical Composition: Wet strength paper often contains additives or chemicals that enhance its wet strength, such as Polyamideamine Epichlorohydrin (PAE), melamine formaldehyde, or other wet strength agents. These chemicals may impact the paper’s composition and properties.
Application-Specific Properties: The properties of wet strength paper can be customized for specific applications. For example, tissue paper with wet strength properties is different from wet strength paper used in labels or packaging materials.
Cost: Producing wet strength paper may be more expensive than regular paper due to the additives and specialized processes involved.
The exact properties of wet strength paper can vary depending on the intended application and the specific formulation used by paper manufacturers. These properties make wet strength paper suitable for various applications, including food packaging, labels, medical products, and industrial applications where moisture resistance is critical.