For procurement specialists and R&D professionals in the chemical and materials industries, a deep understanding of product specifications is crucial for making informed purchasing decisions. Polyurethane, a remarkably versatile polymer, serves a vast array of applications, from flexible foams to rigid structures and coatings. As a dedicated manufacturer and supplier of high-quality chemical intermediates, NINGBO INNO PHARMCHEM CO., LTD. believes in empowering our clients with knowledge about the critical parameters that define material performance. This article focuses on key formulation aspects of polyurethane, such as acid value, hydroxyl value, and viscosity, explaining their significance for B2B buyers.

The Significance of Acid Value in Polyurethane

The acid value of a polyurethane raw material, typically measured in mg KOH/g, quantifies the amount of free acid present. A low acid value, such as the specification of less than 3 mg KOH/g for our products, is highly desirable. High levels of free acid can indicate incomplete reaction during synthesis or potential degradation. In polyurethane processing, a high acid value can lead to several issues:

  • Catalyst Neutralization: Free acids can react with and neutralize catalysts used in polyurethane formulations, leading to slower cure times or incomplete reactions.
  • Corrosion: Acidic residues can be corrosive to processing equipment and potentially to the final product or its application environment.
  • Product Stability: Higher acidity can sometimes compromise the long-term stability and performance of the finished polyurethane product.

As a responsible manufacturer, we maintain rigorous quality control to ensure minimal acid content in our polyurethane offerings, guaranteeing better processability and product integrity.

Hydroxyl Value: A Key Indicator of Reactivity

The hydroxyl value, expressed in g KOH/g, measures the concentration of hydroxyl (-OH) groups within the polyurethane precursor. These hydroxyl groups are essential for the polymerization process, reacting with isocyanates to form the urethane linkages that define the polymer. A hydroxyl value in the range of 300-330 g KOH/g, as found in our product, indicates a high degree of reactivity. This directly influences:

  • Cross-linking Density: A higher hydroxyl value generally allows for a greater degree of cross-linking, leading to stronger, more rigid, or more durable polyurethane products.
  • Reaction Rate: The hydroxyl value directly impacts the speed at which the polyurethane formulation cures.
  • Final Material Properties: It influences characteristics such as hardness, tensile strength, and chemical resistance of the cured polyurethane.

Understanding this value helps formulators predict and control the final properties of their polyurethane products.

Viscosity: Impact on Processability and Handling

Viscosity, measured in centipoise (CPS) at a specific temperature (e.g., 2000-4000 CPS/25°C), is a critical parameter for ease of handling and processing. It affects how easily the liquid polyurethane can be:

  • Mixed: Proper mixing with other components (like isocyanates or additives) is essential for a homogenous reaction.
  • Pumped and Dispensed: Viscosity dictates the type of pumping equipment required and the efficiency of dispensing systems.
  • Applied: Whether sprayed, cast, or molded, the viscosity influences the application method and the quality of the finish.

Our controlled viscosity ensures that our polyurethane products can be readily integrated into various industrial processes, offering convenience and efficiency to our customers. As a reliable supplier, we provide materials that are optimized for practical application.

Why Partner with NINGBO INNO PHARMCHEM CO., LTD.?

By offering polyurethane materials with precisely controlled specifications like low acid value, high hydroxyl value, and optimal viscosity, we empower our clients to achieve superior results. As a dedicated manufacturer and supplier in China, we are committed to providing high-quality raw materials that meet demanding industrial needs. We encourage you to buy with confidence, knowing that our products are backed by rigorous quality control and technical expertise. For specific project requirements or to learn more about our offerings, please request a quote and samples. Partner with us to leverage the full potential of advanced polyurethane chemistry.