The dosage of ATMP (Aminotris(methylenephosphonic acid)) in daily chemicals is not a fixed number but varies significantly based on the product type, desired function, water hardness, and the specific formulation.
However, we can provide clear dosage ranges and the factors that influence them.
Executive Summary
Typical dosage ranges for ATMP in daily chemicals are between 0.1% to 2.0% of the total formulation weight. It is most commonly used in the 0.2% to 0.8% range for standard applications like laundry and dishwashing detergents.
Detailed Dosage Guidelines by Application
Here is a breakdown of how ATMP is dosed in different product categories:
1. Laundry Detergents (Liquid and Powder)
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Function: To sequester calcium and magnesium ions, preventing scale buildup on fabrics and inside the washing machine, and to boost surfactant performance.
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Typical Dosage Range: 0.2% – 1.0%
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For light water hardness: 0.2% – 0.5%
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For moderate to heavy water hardness: 0.5% – 1.0%
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In compact or concentrated detergents, the percentage might be slightly higher to handle the higher concentration of active ingredients.
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2. Automatic Dishwashing Detergents (ADDs)
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Function: Crucial for preventing lime scale and spots on glasses and cutlery. It also protects the dishwasher’s heating element.
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Typical Dosage Range: 0.5% – 2.0%
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This application often requires a higher dosage than laundry due to the heating element, which rapidly precipitates calcium carbonate. Formulations for very hard water areas will use the upper end of this range.
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3. Personal Care Products: Shampoos, Body Washes, Liquid Soaps
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Function: To improve lathering in hard water and reduce soap scum formation on skin and hair.
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Typical Dosage Range: 0.1% – 0.5%
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Dosages are kept lower here for cost and skin sensitivity reasons. The primary goal is to chelate enough ions to improve lather, not to completely soften the water.
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4. Industrial & Institutional (I&I) Cleaners & Hard Surface Cleaners
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Function: To prevent scale and enhance cleaning in products for floors, bathrooms, and other facilities.
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Typical Dosage Range: 0.3% – 1.5%
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The dosage can vary widely depending on the soil load and water hardness in the target environment.
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Key Factors Influencing the Exact Dosage
A formulator will never just pick a number from this list. They will determine the optimal dosage based on:
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Water Hardness: This is the most critical factor. The harder the water (higher Calcium Carbonate, CaCO₃, ppm), the more ATMP is required. A product designed for a global market must be robust enough to handle a wide range of water hardness.
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Presence of Other Builders: ATMP is rarely used alone. It is often part of a synergistic blend with other phosphonates (like HEDP or DTPMP), polymers (like Polyacrylates), or citrates. In a blend, the total dosage of active inhibitors might stay the same, but the amount of ATMP specifically could be lower.
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Compatibility with Bleach: ATMP has good stability with chlorine bleach, but prolonged exposure can lead to some degradation. The formulation and packaging must account for this.
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Desired Function:
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Threshold Inhibition (preventing scale): Requires lower dosages (e.g., 0.1-0.5%).
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Sequestration (fully binding ions): Requires higher dosages, proportional to the ion concentration in the water.
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Cost and Regulatory Constraints: ATMP is cost-effective, but formulators always aim for the minimum effective dose. Furthermore, local regulations on phosphorus content in detergents can limit the maximum allowable dosage.
Comparison with PBTC
As a follow-up to the previous question, ATMP and PBTC are often used for similar purposes. Here’s a quick dosage comparison:
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Calcium Tolerance: PBTC has significantly better calcium tolerance than ATMP. This means in formulations with very high calcium ions (either from water or other ingredients), PBTC is less likely to precipitate and will remain effective at a lower dosage. ATMP might require a higher dose or a different builder system to achieve the same result in very hard water.
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pH Stability: Both are stable over a wide pH range, but PBTC is generally considered to have slightly better stability in highly acidic or highly alkaline conditions.
Conclusion
While a typical formulator might start with a dosage of 0.5% ATMP for a laundry detergent and then adjust based on testing, it is crucial to understand that the final amount is a carefully balanced decision. It depends on a complex interplay of water chemistry, other ingredients, performance requirements, and cost/environmental targets. For a consumer, looking for products marketed for “hard water” is a good indicator that they contain effective levels of scale inhibitors like ATMP.