Sealant compounding

Silicon. Gaskets sealant compound, antifreeze, oil antifoam, sand and dirt... 

Depending on their chemical composition, molecular structure and molecular weight, silicone compounds are used as liquids, oils and lubricants of various consistency, as elastomers (for sealants, compounds and rubbers), as well as polymers for varnishes, plastic laminates and films. 

Flick, E. W., Adhesive and Sealant Compound Formulations, 2d ed., Noyes Publications, New York, 1984. 

The hot dip process is used to coat wire baskets, brackets etc., and depends on preheating the object to be coated (100-120 °C) and dipping it into the plastisol where the PVC gels around the object. Cold dip and spray coating is used on fabrics, such as lined gloves, or metal, such as underbody sealant. These are subsequently gelled in an oven. The use of an infrared system to cure PVC sealant compound has also been introduced (343). 

Flick, E.W. "Adhesives and Sealant Compounds and Their Formulations" Noyes Data Corp., Park Ridge, NJ, 1978. 

Almost all silicone sealant compounders use some percentage of a silica filler for achieving desired tensile strength. Most use a fumed silica which can be illustrated as follows ... 

Now that the ingredients are defined, the nature of vulcanization can be discussed. Vulcanization occurs through the cross-linking system. The system shown below is the system used by many major silicone sealant compounders around the world, to make high and medium modulus sealants. It consists of hydroxyl-ended poly-... 

Virtually all rubber materials, and plastic materials, can be made into an adhesive or sealant compound. This is because many elastomers begin as monomers dispersed in water or solvent and are polymerized in situ. Latex products can remain so, while solid elastomers that are extracted from either water or solvent systems can be solvated with an appropriate organic solvent system. In addition, most solid elastomers exhibit thermal flow characteristics which can make them suitable for hot-melt formulations. And since there are many different rubber polymer families, it stands to reason that there will be many different rubber-based adhesives to identify and describe. Some, however, have... 

Flick, E., ed Adhesives and Sealant Compound Formulation, 2nd ed Noyes Publications, Park Ridge, NJ, 1989. 

Lap shear adhesion was measured using steel coupons overlapped 2.5 cm. Spacers were used between the coupons to obtain a uniform sealant thickness of 0.18 cm. Light pressure was applied so the upper coupon would bear evenly on the spacers. The sealant compounds were then cured at 160 °C for 25 minutes and then tested at room temperature. 

Aromatic oil is used in asphalt modification, in waterproofing and sealant compounding, and in adhesives. It can also be further processed into fuel oil as well. 

These highly refined paraffinic oils are also used in agriculture sprays, coatings, textile specialties, sports equipment, footwear, dust control, white oil feedstock, paper and pulp process defoamers, insecticide carriers, and caulking and sealant compounds. 

Sealant compound, silicone rubber base (for caulking, sealing, and glazing buildings and other structures)... 

Sealant compound, single component, butyl rubber based, solvent release type (for buildings and other types of construction... 

Test for adhesion and cohesion of elastomeric joint sealants under cyclic movement Test for extrudability after package aging of latex sealing compounds Test for aging effects of artificial weathering on latex sealing compounds Test for volume shrinkage of latex sealant compounds... 

Enjay Butyl LM-430—Sealants—Compounding Guide, Enjay Polymer Labs [now Exxon Polymer Labs] EPL-7204-597, March 1972. 

FUck E. Adhesives and sealant compound formulation. 2nd ed. Park Ridge, NJ Noyes PubUcations 1989. 

K > Na > Li. After neutralization or removal of the catalyst, fluid polymers are used as is or to formulate grease compounds. If a reactive end blocking group was incorporated during polymerization, the fluid polymer is then useful for making a coating, a sealant, or a Hquid mbber product. 

Hydrocarbon resins are used extensively as modifiers in adhesives, sealants, printing inks, paints and varnishes, plastics, road marking, flooring, and oil field appHcations. In most cases, they ate compounded with elastomers, plastics, waxes, or oils. Selection of a resin for a particular appHcation is dependent on composition, molecular weight, color, and oxidative and thermal stabiHty, as weU as cost. A listing of all hydrocarbon resin suppHers and the types of resins that they produce is impractical. A representative listing of commercially available hydrocarbon resins and their suppHers is included in Table 6. 

One-part urethane sealants (Table 3) are more compHcated to formulate on account of an undesirable side reaction between the prepolymer s isocyanate end and water vapor which generates carbon dioxide. If this occurs, the sealant may develop voids or bubbles. One way to avoid this reaction is to block the isocyanate end with phenol and use a diketamine to initiate cure. Once exposed to moisture, the diketamine forms a diamine and a ketone. The diamine reacts with the isocyanate end on the prepolymer, creating a cross-link (10). Other blocking agents, such as ethyl malonate, are also used (11). Catalysts commonly used in urethane formulations are tin carboxylates and bismuth salts. Mercury salt catalysts were popular in early formulations, but have been replaced by tin and bismuth compounds. 

An important use of bromine compounds is in the production of flame retardants (qv). These are of the additive-type, which is physically blended into polymers, and the reactive-type, which chemically reacts during the formation of the polymer. Bromine compounds are also used in fire extinguishers. Brominated polymers are used in flame retardant appHcations and bromine-containing epoxy sealants are used in semiconductor devices (see... 

The Hquid polymer is then compounded with metal oxides or peroxides, as weU as fillers (carbon black) and can undergo cold vulcanization, ie, chain extension and cross-linking iato a soHd matrix. It is largely used as a sealant and gasket material for wiadows, automobile wiadshields, etc. 

Polyisobutylene is produced ia a range of mol wts, and has found a host of uses. The low mol wt Hquid polybutenes have appHcations as adhesives, sealants, coatings, lubricants, and plasticizers, and for the impregnation of electrical cables (7). Moderate mol wt polyisobutylene was one of the first viscosity-iadex modifiers for lubricants (8). High mol wt polyisobutylene is used to make uncured mbbery compounds, and as an impact additive for thermoplastics. 

A partially cross-linked, isobutylene—isoprene—divinylbenzene terpolymer containing some unreacted substituted vinylbenzene appendages is commercially available from Polysar Division, Bayer AG. Because of the residual reactive functionality, it can be cross-linked by peroxides that degrade conventional butyl mbbets. It is employed primarily in the manufacture of sealant tapes and caulking compounds (31). 

Polybutenes enjoy extensive use as adhesives, caulks, sealants, and glaring compounds. They are used as plasticizers in mbber formulations with butyl mbber, SBR, and natural mbber. In linear low density polyethylene (LLDPE) blends they induce cling to stretch-wrap films. Polybutenes when modified at their unsaturated end groups with polar fiinctionahty are widely employed in lubricants as dispersants. Blends of polybutene with polyolefins produce semisoHd gels that can be used as potting and electrical cable filling materials. 

Adhesives, Coatings, and Sealants. Eor these appHcations, styrenic block copolymers must be compounded with resins and oils (Table 10) to obtain the desired properties (56—58). Materials compatible with the elastomer segments soften the final product and give tack, whereas materials compatible with the polystyrene segments impart hardness. The latter are usually styrenic resins with relatively high softening points. Materials with low softening points are to be avoided, as are aromatic oils, since they plasticize the polystyrene domains and reduce the upper service temperature of the final products. 

The hydrogenated materials have a higher maximum service temperature than the conventional SBS materials and, because of the absence of double bonds in the chain, better weathering properties. Known as SEBs these materials now find use in adhesives, sealants and roofing membrane compounds. These also find use in highly filled automotive acoustic barriers and in medical, sports and leisure applications. 

Another common device used in the rubber industry is the thin film evaporator. This device is very often used in the manufacture of ultra-low molecular weight elastomers that are used in sealant applications or specialty coatings, and as processing aids in conventional rubber compounding processes. The thin film evaporator described earlier, has found a multitude of other industry applications, including food processing operations. 

In addition to the petrolatum tapes and those based on a laminate of p.e. or p.v.c. with an elastomeric sealant or pressure-sensitive adhesive layer, recent developments have centred around self-adhesive bituminous laminates. These tapes are commonly constructed with a p.v.c. backing, whose thickness ranges from 0 08 to 0 75 mm and a bituminous adhesive compound layer to provide a total tape thickness of up to 2 mm. In order to maintain conformability without compromising impact values, tapes may also be manufactured with a fabric reinforcement within the bituminous layer. 

Epoxies Powder, one and two-part liquids and paste Many types of resins available, providing wide spectrum of properties. Easy to compound. Low shrinkage and excellent dimensional stability. Good to excellent adhesion. May be cast or molded. Coatings, sealants, adhesives, solderless PC boards. 

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