Kuraray Poval 22-88

1. Why Yankee Coating Systems Increasingly Rely on High-Performance PVOH With the upgrading of global tissue paper consumption, the market's comprehensive requirements for the softness, strength, bulkiness, and absorbency of tissues are constantly increasing. To achieve this balance of performance, traditional DCT (Dry Crepe Technology) is gradually becoming insufficient to meet the demands, and structured forming technologies such as TAD, NTT, eTAD, and QRT are widely used. The advantages of PVOH are: Good water solubility and high system compatibility Tuned molecular structure and high application flexibility Predictable impact on peel force and wrinkling behavior This makes it a "structural material" in the high-end tissue paper Yankee coating system, rather than a simple additive.     2. The Influence of PVOH Viscosity and Concentration on Coating Rheological Behavior At the same concentration, the viscosity of solutions with different molecular weights of PVOH varies significantly. However, in actual coating, the extended viscosity behavior as a function of concentration is more important. Low-viscosity PVOH (Kuraray Poval 22-88): Easy to handle and sprayable, but with limited support under high-load peeling. Medium-high viscosity PVOH (Kuraray Poval 22-88): Achieves a good balance between coating integrity and operational stability. Ultra-high molecular weight PVOH (Kuraray Poval 200-88 KX): Forms a highly ductile coating network even at lower concentrations, contributing to improved "effective adhesion time" on Yankee surfaces.     3. Performance Focus Due to Differences in Hydrolysis Degree Besides molecular weight, the degree of hydrolysis also determines the application boundaries of PVOH: 88% Hydrolysis Degree: Good water solubility, suitable for coating systems with large dynamic changes, and is the mainstream choice for current structured tissues. 99% Hydrolysis Degree (Elvanol 90-50): Dense film formation, stronger water resistance, suitable for paper machines requiring longer coating life or high humidity operating conditions. In practical formulations, the adhesion and peelability of coatings are often precisely controlled by blending PVOHs with different degrees of hydrolysis.   4. PVOH Selection Approach Based on Application Objectives When selecting PVOH for the Yankee coating system, the following factors should be given priority consideration: Paper machine speed and Yankee surface temperature The balance between the softness and strength of the target paper The synergistic effect of the overall coating chemical system   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

With the continued growth in demand for high-end tissue paper, tissue products are no longer solely focused on absorbency, but also require higher standards for softness, strength, surface structure, and operational stability. To meet these demands, paper machine technology is constantly being upgraded, and various structured tissue paper processes are being widely adopted. Against this backdrop, the stability and performance boundaries of the Yankee Coating formulation system have been significantly amplified, and PVOH (Polyvinyl Alcohol) is becoming one of the key materials determining coating performance.   1. What New Challenges Does the Upgraded Tissue Paper Processing Present to Yankee Coating? Traditional dry creping processes have relatively mild requirements for coatings, while the new generation of structured tissue paper processes places more complex demands on coatings during the forming and peeling stages, mainly in three aspects. First, higher adhesion stability. Under high-speed operating conditions, the residence time of the paper sheet on the Yankee drying cylinder surface is shortened, requiring the coating to form a stable and continuous functional film layer in a shorter time to avoid localized delamination or uneven adhesion. Second, stronger shear resistance. High linear speeds and more frequent doctor blade action expose coating materials to a prolonged high-shear environment, making low-molecular-weight or structurally unstable PVOH prone to performance degradation. Thirdly, the operating window narrows. High-end paper machines are more sensitive to coating dosage, concentration, and viscosity control; fluctuations can easily affect paper web peeling, energy consumption, and paper quality. These changes mean that the molecular structure of PVOH is no longer merely a matter of "usability," but has become a core variable for system stability. 2. How PVOH Molecular Weight and Viscosity Affect Coating Film Formation and Peeling Performance PVOH is essentially a linear polymer, and its molecular weight directly determines solution viscosity, film strength, and cohesiveness. In Yankee Coating applications, high-molecular-weight PVOH often exhibits the following advantages: First, better film continuity. Enhanced entanglement between polymer chains makes it easier for the coating to form a uniform, dense film on the drying cylinder surface, reducing microcracks and localized defects. Second, a more controllable balance between adhesion and release. Appropriately increasing the molecular weight and system viscosity can improve wrinkling structure by ensuring stable paper adhesion and enabling predictable peeling behavior through the doctor blade. Third, it offers stronger resistance to dilution and shearing. In actual operation, the coating is affected by multiple factors such as moisture, temperature, and mechanical shearing; the performance degradation rate of high molecular weight PVOH is significantly slower. It is important to note that higher molecular weight is not always better. Excessively high viscosity may lead to difficulties in dissolution, increased pumping pressure, and slower system response; therefore, a balanced design must be implemented based on equipment conditions.   3. The Practical Value of High-Viscosity PVOH in High-End Tissue Paper From operational practice, high-viscosity, high-molecular-weight PVOH demonstrates three main values ​​in the production of high-end tissue paper. First, it improves the stability of paper machine operation. A stable coating film reduces the need for frequent adjustments to the formulation and doctor blade pressure, facilitating long-term continuous operation. Second, it reduces unit consumption. Due to higher film-forming efficiency, the coating amount can be appropriately reduced to achieve the same adhesion effect, thereby reducing overall chemical consumption. Third, it improves paper consistency. Reduced coating performance fluctuations result in more stable feel, strength, and surface structure of the finished paper, mitigating batch-to-batch variation risks. For high-end tissue paper production lines, PVOH is no longer merely an auxiliary chemical, but a key material affecting product quality and operational efficiency.     4. Technological Innovation of Kuraray Poval 200-88 KX The unique feature of Kuraray Poval 200-88 KX lies in its branched structure. Ordinary PVOH is mostly a linear polymer, and its increased viscosity often leads to decreased operability. However, 200-88 KX boasts a viscosity of 200 mPa·s at a 4% concentration, far exceeding traditional models (such as Kuraray Poval 22-88 22 mPa·s). This high molecular weight and unique branched design deliver significant performance advantages: Wider operating window: Adapts to variations in temperature and humidity. Excellent shear-thinning behavior: Maintains good flowability during high-speed spraying, yet rapidly forms a film upon contact with the drying cylinder. Increased productivity: Improved paper gripping on the Yankee cylinder significantly enhanced the paper machine's performance and reduced paper breakage.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com