Inhibitor 701: The Key to Enhancing Monomer Storage Safety

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.

Inhibitor 701 (4-Hydroxy-TEMPO, CAS 2226-96-2) is a highly efficient and stable free radical scavenger specifically used to prevent the self-polymerization of monomers such as acrylic acid, styrene, and unsaturated resins during storage and transportation. It features high inhibition efficiency, excellent thermal stability, and superior safety, making it a key additive for ensuring the long-term stability of monomers and production safety.

I. What is Inhibitor 701?

Polymerization Inhibitor 701 (Chemical Name: 4-Hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, English Name: 4-Hydroxy-TEMPO / TEMPOL, CAS No.: 2226-96-2) is a stable free radical compound belonging to the class of piperidine-N-oxyl inhibitors. Its primary function is to capture free radicals, preventing the self-polymerization of unsaturated monomers during storage and transportation, thereby ensuring monomer stability and safety.

Compared to traditional phenolic inhibitors, Inhibitor 701 offers advantages including higher inhibition efficiency, better thermal stability, and a broader application scope. Consequently, it is widely used for the stable storage of acrylates, styrene, unsaturated polyester resins, and other easily polymerizable monomers.

II. Mechanism of Action in Monomer Storage

Monomers are highly susceptible to heat, light, impurities, or metal ions during storage and transportation, which can initiate free radical chain reactions leading to self-polymerization.

Mechanism of Inhibitor 701: It rapidly combines with free radicals to form stable nitroxyl radical intermediates, thereby terminating the polymerization chain growth and preventing monomer degradation.

Effect: After adding Inhibitor 701, monomers maintain good stability even under high-temperature conditions, prolonged storage, or during transportation, significantly reducing the risks and losses associated with polymerization.

III. Addition Methods and Recommended Dosage

Addition Methods:

    Direct Addition: Polymerization Inhibitor 701 can be directly added into the monomer system and mixed uniformly.

    Solution Method: Dissolve Inhibitor 701 in ethanol, methanol, or acetone before adding to ensure uniform dispersion.

    Batch-wise Replenishment: Suitable for long-distance transportation or extended storage scenarios; added in stages to maintain a continuous effect.

Recommended Dosage:

    Acrylic acid and its esters: 0.005% – 0.02%

    Styrene and its derivatives: 0.01% – 0.03%

    Unsaturated polyester resins: 0.01% – 0.05%

⚠ Note: Insufficient dosage may lead to incomplete inhibition, while excessive dosage might affect the efficiency of subsequent polymerization reactions. Adjustments should be made based on actual conditions.

IV. Usage Precautions

Storage: Store in a cool, dry, and dark place, sealed tightly. Avoid contact with strong oxidizing agents.

Handling: Wear protective gloves and goggles during addition or weighing. Avoid dust inhalation and direct skin contact.

Timing of Application: It is recommended to add Polymerization Inhibitor 701  *before* monomer storage or transportation to ensure long-term system stability.

As an efficient free radical scavenger, Inhibitor 701 plays a crucial role in enhancing the safety of monomer storage. Through scientific addition methods and appropriate dosage control, companies can significantly reduce the risk of monomer self-polymerization, ensure product quality, and improve the safety standards of production and transportation.