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Diak™ Curing Agents for Viton® Fluoroelastomers
There are three members of the family of Diak curing agents—Diak No. 1, No. 3, and No. 7. Diak Nos. 1 and 3 are diamines and find application in the curing of the A, B, and E types of Viton fluoroelastomer. Diak No. 7, a reactive polyfunctionaltriazine, is a coagent necessary for use with the G family of peroxide-curable Viton fluoroelastomers. The Diak curing agents differ in their curing activity depending upon the conditions and the polymer in which they are used. This bulletin gives product descriptions for the three Diak curing agents as well as their principal properties and applications. Also included are appropriate references totechnical literature reporting test results of Diak curing agents in different polymers and under different conditions. The data in this report compares the performance of the various Diak curing agents with each other. Many of the property and processing characteristics for compounds of Viton (particularly compression set, scorch safety, and cure rate) can be improved still further through the useof the Viton Curative Masterbatches (Curative No. 20 and No. 30 or No. 20 and No. 40). For information on curing with the Curative Masterbatches, see DuPont Dow Elastomers technical bulletin H-73596-01, “Compounding with Viton® Curative Masterbatches.” Where FDA-approved vulcanizates of Viton are required in the formulation of rubber articles intended for repeated use in contact with food, Diak No.1 should be used. For more information, see DuPont Dow Elastomers technical bulletin H-71103-02, “Viton® in Applications Regulated by the Food and Drug Administration.”
Diak Nos. 1 and 3 curing agents may form flammable dust-air mixtures. Also, they may cause irritation of eyes and skin. Keep away from heat, sparks, and open flame. Use only in areas provided with groundedequipment. Breathing of dust and contact with eyes, skin, and clothing should be avoided. Wash thoroughly after handling. Good ventilation should be provided during all processing and curing operations; avoid dust hazards. Avoid breathing vapors during processing. In rat inhalation studies on Diak No. 3, the Approximate Lethal Concentration (ALC) was found to be 6.2 mg/L of air for an exposureperiod of 4 hr. Observations indicated that there was an irritating effect on the respiratory system. If Diak No. 3 is inhaled, remove to fresh air. If not breathing, give artificial respiration, preferably mouth-to-mouth. If breathing is difficult, give oxygen. Call a physician. Diak No. 7 curing agent should be stored and used above its melting point (25 ± 2°C [77 ± 4°F]). Preferable temperaturerange for storage and use is 30–40°C (85–105°F). Like the other Diak curing agents, it may cause irritation. Contact with eyes, skin, and clothing should be avoided. Wash thoroughly after handling. For all three Diak curing agents, in case of contact, immediately flush eyes with plenty of water for at least 15 min. Call a physician. Flush skin with water.
Diak Nos. 1 and 3 arewidely used to cure the A, B, and E types of Viton fluoroelastomer. The main difference between the Diak curing agents is in processing safety. Diak No. 1 gives the least processing safety, while Diak No. 3 gives the best and, at the same time, exhibits some plasticizing effect. In general, the compression set and physical properties obtained with Diak No. 3 are not quite as good as with Diak No.1.
Diak™ No. 1—Product Description
Chemical composition Hexamethylenediamine carbamate
Diak No. 3—Product Description
H C H C H C N (CH 2 )6 N
H C H C H C
+ H3 N
CO 2 (CH 2 )6 N H
Physical form Color Odor Specific gravity at 25/4°C (77/39°F) Decomposition point Ash Moisture Purity Solubility Storage stability...