Properties and Applications of KR-445 Acrylic Acid Homopolymer

KR-445 is a low-molecular-weight acrylic acid homopolymer (polyacrylic acid / PAAS equivalent) widely used as a high-performance dispersant, anti-redeposition agent, and scale inhibitor. It is commercially designed as an equivalent/alternative to industry-standard acrylic polymers like Dow ACUSOL™ 445.

It is typically supplied in two main forms:

KR-445 (Standard / Acidic Form): Partially neutralized polyacrylic acid.

KR-445N (Neutralized Form): Fully neutralized polyacrylic acid sodium salt.

1. Technical Specifications & Typical Properties

Parameter KR-445 (Partially Neutralized) KR-445N (Fully Neutralized)

Chemical Name Polyacrylic Acid (PAA) Polyacrylic Acid Sodium Salt (PAAS)

Appearance Clear, colorless to pale yellow liquid Clear, colorless to pale yellow liquid

Average Molecular Weight (Mw) ~4,500 g/mol ~4,500 g/mol

Solid Content (%)  48.0%  45.0%

pH (as is at 20°C) 3.0 - 4.5 6.0 - 9.0

Density (20°C)  1.20 g/cm3  1.30g/cm3

Viscosity (20°C) 100 - 1,000 mPa.s (cps) 300 - 1,300 mPa.s (cps)

2. Key Chemical & Performance Properties

Optimized Molecular Weight (4,500g/mol): The narrow molecular weight distribution maximizes its ability to disrupt crystal growth without excessively increasing fluid viscosity.

Threshold Inhibition & Crystal Distortion: Acts via sub-stoichiometric scale control. It distorts the crystal lattice structure of inorganic salts, converting rigid scale into non-adherent, loose sludge.

Exceptional Calcium Carbonate (CaCO3) Inhibition: Demonstrates high threshold effectiveness against CaCO3 precipitation, as well as solid performance against CaSO4,BaSO4, and silicates.

Silt & Particle Dispersion: Imparts a h3 negative charge (zeta potential) onto suspended solids, preventing particulate agglomeration (clay, mud, iron oxide, and organic soils).

High Thermal & Chlorine Stability: Maintains dispersant performance under high-temperature operating conditions (e.g., boilers, heat exchangers) and in the presence of hypochlorite/bleach oxidants.

3. Main Industrial Applications

A. Detergent & Cleaning Formulations

Anti-Redeposition Agent: Used in liquid and powder laundry detergents to suspend particulate soil (especially clay/mud), preventing it from redepositing onto fabrics during wash cycles.

Fabric Whiteness & Anti-Encrustation: Prevents insoluble calcium and magnesium salts from depositing on textiles, keeping fabrics soft and avoiding greying/stiffening over time.

Institutional & Industrial (I&I) Cleaning: Inhibits filming and spotting on glass and stainless steel surfaces in automatic dishwashing (warewash) systems.

B. Industrial Water Treatment

Circulating Cooling Water Systems: Functions as a scale inhibitor and sludge dispersant in cooling towers for power plants, steel mills, chemical manufacturing, and refineries.

Boiler & Geothermal Systems: Prevents mineral scale buildup on heat exchange surfaces and maintains suspended particulate matter in a fluid state for easy blowdown removal.

Boiler & Formulation Blends: Frequently blended with phosphonates (such as HEDP, ATMP, or PBTC) and zinc salts to create synergistic scale and corrosion inhibitor packages.

C. Textile Processing & Dyeing Auxiliaries

Bleach Stabilization: Enhances hydrogen peroxide bleach bath stability by dispersing insoluble trace impurities.

Scouring & Washing: Serves as a dispersant during scouring processes to eliminate soil and mineral buildup from raw fibers.

4. Recommended Storage & Handling

Storage Conditions: Store in original, tightly sealed containers in a cool, dry, well-ventilated area. Avoid direct exposure to freezing temperatures or excessive heat.

Shelf Life: Typically 10 to 12 months under standard room storage conditions.

Materials Compatibility: Suitable for storage in HDPE, FRP, polypropylene, and stainless steel tanks. Avoid prolonged contact with mild steel when using the unneutralized acidic grade (KR-445).