Application and Advantages of Inhibitor 701 in Acrylic Ester Monomers

Basic Information

Chemical Name (Chinese): Inhibitor 701

Synonyms: Piperidinol oxide, 4-Hydroxy-TEMPO

CAS No.: 2226-96-2

Molecular Formula: C9H18NO2

Molecular Weight: 172.24

EINECS No.: 218-760-9

Appearance: Orange-red crystals

Uses:

1.  It exhibits a good inhibitory effect on acrylates, methacrylates, acrylic acid, acrylonitrile, styrene, and butadiene.

2.  Used to prevent the self-polymerization of olefin monomers during production, separation, purification, storage, or transportation, and to control and regulate the degree of polymerization of olefins and their derivatives.

1. Introduction to Inhibitor 701

Inhibitor 701 (BHT, chemical name: 2,6-Di-tert-butyl-4-methylphenol, CAS No.: 2226-96-2) is a highly efficient phenolic antioxidant and polymerization inhibitor. It offers exceptional free radical scavenging capability and thermal stability, effectively preventing the spontaneous polymerization of acrylic ester monomers during storage, transportation, and processing.

2. Why Acrylic Ester Monomers Are Prone to Polymerization

Acrylic ester monomers (e.g., methyl acrylate, butyl acrylate, hydroxyethyl acrylate) contain highly reactive carbon-carbon double bonds, making them susceptible to free radical polymerization under the following conditions:

Light Exposure: Ultraviolet light can initiate free radical formation.

High Temperature: Elevated temperatures accelerate the polymerization rate.

Presence of Metal Ions: Certain metal ions can act as polymerization catalysts.

Peroxide Residues: Residual initiators may trigger unwanted self-polymerization.

Without an effective inhibitor, monomers can polymerize prematurely during storage or transit, leading to product degradation, pipeline blockages, and potential safety risks.

3. Key Advantages of Using Inhibitor 701 in Acrylic Ester Monomers

4. Usage Guidelines and Precautions

Addition Timing: It is recommended to add Inhibitor 701 during the monomer cooling phase to ensure homogeneous mixing.

Dissolution Method: Can be added directly or pre-dissolved in an organic solvent (e.g., toluene, acetone) before incorporation.

Recommended Dosage:

Short-term storage: 0.005% – 0.01%

Long-term storage or ocean freight: 0.02% – 0.05%

Important Precautions: Avoid contact with metal ions and strong oxidizing agents. Store in a cool, dry place.

5. Typical Application Case Study

A chemical exporter faced challenges with premature polymerization of Methyl Methacrylate (MMA) during long ocean shipments, which involved significant temperature variations. By incorporating 0.02% Inhibitor 701, the monomer remained stable throughout the 45-day maritime transit, with polymerization levels kept near zero. This solution drastically reduced product returns and loss risks.

6. Conclusion

Inhibitor 701 (BHT, CAS 2226-96-2) plays an indispensable role in the storage and transportation of acrylic ester monomers. Its proper use ensures product stability and safety, minimizes logistical risks, and enhances overall market competitiveness. For producers and users of acrylic esters, Inhibitor 701  represents a reliable and cost-effective choice.