Additives cure accelerators

The manufacture of the majority of fluorocarbon elastomer gums includes the addition of an incorporated cure system comprising an organic onium cure accelerator, such as triphenylbenzylphosphonium chloride [1100-88-5] and a bisphenol cross-linking agent, such as... 

Resoles are usually those phenolics made under alkaline conditions with an excess of aldehyde. The name denotes a phenol alcohol, which is the dominant species in most resoles. The most common catalyst is sodium hydroxide, though lithium, potassium, magnesium, calcium, strontium, and barium hydroxides or oxides are also frequently used. Amine catalysis is also common. Occasionally, a Lewis acid salt, such as zinc acetate or tin chloride will be used to achieve some special property. Due to inclusion of excess aldehyde, resoles are capable of curing without addition of methylene donors. Although cure accelerators are available, it is common to cure resoles by application of heat alone. 

Effects of Various Additives on Accelerated Grafting and Curing Reactions Initiated by UV and Ionizing Radiation... 

The gluability of the lignin-epoxy resin adhesives was found to be improved by the addition of calcium carbonate (50% by weight) to the liquid resin. This must be attributed to the nature of the weak alkali in calcium carbonate as a cure accelerator, and to the reinforcement effect of fillers. Since wood surfaces are acidic, the addition of alkaline fillers effectively alters the pH of the glue line. 

A composition is prepared by dissolving the MMBS modified thermoset resin in acetone. To the resulting solution, additives may be added, for example, pigments, flame retardants, lubricants or cure accelerators, e.g., hexamethylenetetramine. 

A typical cationic uv adhesive formulation contains an epoxy resin, a cure-accelerating resin, a diluent (which may or may not be reactive), and a photoinitiator. The initiation step results in the formation of a positively charged center through which an addition polymerization reaction occurs. There is no inherent termination, which may allow a significant postcure. Once the reaction is started, it continues until all the epoxy chemistry is consumed and complete cure of the resin has been achieved. Thus, these systems have been termed living polymers. 

Resin II contains tetraglycidyl methylene dianiline (TGMDA) as the principal epoxide with small amounts of a cresol novolac and DGEBA. DICY as curing agent is present in an amount such that the amine epoxy ratio is 0.25. Diuron is the accelerator. The supplier s recommended standard cure is the same as for SP250. However, in this system approximately 20 percent of the epoxide remains unreacted following the cure cycle (1 ). Selected resin plates were subjected to additional cure at 170°C and 220°C. The samples post cured at 220 C for forty minutes showed no residual epoxide absorbance in the IR spectrum. 

Uses Carrier in inks hard resin additive in overprint varnishes reactive polyol in melamine- and urethane-cured coatings for wood and metal intermediate for polyester and alkyd coatings cure accelerator, hardener, gloss aid, chem. resist, aid in coatings Properties Wh. pastilles sol. ( 25% solids) in Arcosolv soivs., butanol, NMP insol. in water, propylene glycol, and ethylene glycol m.w. 2500 (wt. avg.) bulk dens. 5.556 Ib/gal acid no. < 0.1 hyd. no. 255 VOC 0.10%... 

Uses Fertilizer animal feed supplement stabilizer for resins, plastics, explosives softener for cellulose in paper industry deodorizer penetrant cure accelerator and activator airport runway deicing agent dispersant (animal glue, proteins) plasticizer for starch adhesives food additive, yeast nutrient, fermentation aid flour treatment agent diuretic, antiseptic in pharmaceuticals antistat, humectant in cosmetics keratin softenerfor dry skin prods. in ammoniated dentifrices in side seam cements for food-contact containers... 

The effect of temperature on the curing time is relatively small for condensation-curing rubbers, i.e. a system with low reactivity at room temperature, and thus with long pot life, cannot be accelerated considerably by applying heat, whereas addition-curing rubbers, even if they have long pot lives at room temperature, will cure within a few minutes at temperatures near to 200°C. 

The two-part sihcone adhesive/sealants do not require moisture to cure and produce a superior deep-section cure. Two types are available addition-cure and condensation-cure. Addition of curing produces no by-products, can be heat-accelerated, produces negligible shrinkage, and provides the best high-temperature resistance of all silicone adhesives. Condensation-cure silicones are not easily inhibited and can be used on a greater variety of materials. ... 

The cure times can be reduced by use of special accelerators, namely Vulkacit 600 or Demorapid DA, both organic lead salts. These accelerators do not become effective below 90°C, and provided milling temperatures are kept below this level the storage life of the compound is not affected by their use. Although the Urepan 600 compound is virtually cured at the above times and temperatures, it has been found that an additional post-cure is desirable. This additional cure can take the form of storage at room temperature for 8 days or an oven cure for a few hours at 1 lO C. Table 7.10... 

---