Sealants, windshield

Polyurethane sealant formulations use TDI or MDI prepolymers made from polyether polyols. The sealants contain 30—50% of the prepolymer the remainder consists of pigments, fiUers, plastici2ers, adhesion promoters, and other additives. The curing of the sealant is conducted with atmospheric moisture. One-component windshield sealants utili2e diethyl malonate-blocked MDI prepolymers (46). Several polyurethane hybrid systems, containing epoxies, siUcones, or polysulfide, are also used. 

Windshield sealants comprise some of the most significant applications of one-component urethane adhesives. Several years ago, the requirements for these sealants were increased. In an accidental rollover, in certain automobiles, the windshield becomes a structural part of the car. Therefore, the windshield adhesive, which holds the windshield in place, must have structural strength. An example of a one-component windshield sealant is shown below [48] ... 

Automobile Windshield Sealant - (Seals windshield into metal cavity)... 

Windshield sealants, swimming Methyl vinyl United States 3,462,516 1969 Phillips Petroleum... 

Preformed Tapes. Preformed tapes of butyl, usually vulcanized, are extruded semisolid sections with pressure-sensitive adhesion. Since they are 100% solid, there are no problems of shrinkage or solvent evaporation. Sold in rolls interlined with release paper, they are often used together with liquid sealants or solid spacers, shims, etc. They vary from low cost, highly polybutene-extended tapes for trailers and mobile homes, to partially or fully vulcanized butyl rubbers with little polybutene content for high-rise glazing and automotive windshield sealants. 

Many formulations of two-component polysulfide sealants are available. All have a base component containing the LP polymer and an activator component containing the curing agent. (Automotive windshield sealants, formerly important in the industry, have two activator components.)... 

Due to their dependability, versatility, and durability, silicone sealants have found use for the consumer market. These uses include bathtub caulk, auto sealants, windshield sealants, window sealants, high temperature gaskets, and general household glues and sealants. 

Windshield sealants - One part polymethane sealants are the main product used in sealing auto windshields at the factory. They are used in conjunction with a silane primer to increase their adhesion to the metal frame. Butyl rubber tapes are used by repair shops to replace broken windshields. 

One application for a two-part urethane adhesive is a windshield adhesive/sealant... 

Major polymer applications safety glass interlayer (automotive windshields), control of light, heat and sound in construction glass, bulletproof glass, adhesives and sealants, binders for rocket propellant, photoconductive papers, magnetic tapes, powder coating, wood sealers and primers, inks, ceramic binders, dry toners, wash primers, composite fiber binders... 

Butadiene, 2-methyl-, polymer with 2-methyl-1-propene Butyl rubber Isobutylene/isoprene co-polymer Kalar 5214 Kalat 5263 Kalene 800 2-Methyl-1,3butadiene polymer with 2-methyl-1-propene Poly(isobutylene-co-isoprene). Cross-linked butyl composition produces nonsagging butyl-based sealants, e.g., automotive windshield tape, hot melt sealant as base for butyl mastics Viscosity (Mooney, ML 1- 8,100°) = 42-52. Hardman. 

Silicone adhesives and sealants are used in many advanced fields of technology where extreme environmental conditions are experienced, for example, in Aerospace applications, as coatings for firewalls, windshields and other thermal barriers, and for corrosion protection. 

One-part polyurethane adhesives have been formulated to cure at room temperature or at elevated temperatures. With the room temperature systems, cure may be brought about by the reaction of free isocyanate with moisture as discussed in Section II. These materials are typically used as adhesives/sealants for the bonding of porous substrates, for example, wood and concrete. They are also being used for the bonding of automobile windshields. " Such bonding incorporates the windshield into the automotive body as an integral structural member which contributes to the... 

Structural glazing Surface preparations Teak decks Test of a bead Thickness of the joint Transport equipment Uneven stress distribution UV radiation Waterswelling sealants Wettability Windshield bonding Woehler diagram. 

The new steel panels used in vehicles are not as heavy as in older cars but, being thinner, are not as strong. The use of PU windshield adhesive/sealants to replace the traditional butyl sealants has enabled the windshield to become a structural part of the vehicle because it supports the roof. OEM adhesives are typically one-component moisture-cured urethanes that take several hours to cure and give bonds with tensile shear strengths of 5-8 MPa. The products are pigmented black to give resistance to UV. After-market adhesives... 

Hot Melt, Field-Extruded Sealants. Several butyl raw material manufacturers and sealant producers have recently developed butyl tapes. These are premasticated, high viscosity thermoplastic compositions that are fed as talced ribbons into a polymeric sealant applicator (PSA). Within the PSA, the compound is heated and extruded into the joint opening to form a smooth joint that cools rapidly with excellent adhesion claimed, even to oily or otherwise poorly prepared surfaces. These hot-applied, post-formed butyl tapes have been successfully used to seal insulated glass units, automotive windshields (Fig. 4), curtain walls, concrete pipes, precast concrete structural joints, and as bedding compounds in combi-... 

Polyurethanes are the most versatile polymer systems used to formulate elastomeric sealants. Polyurethane sealants are sold both as two-component and one-component gun-grade compositions, packed in cartridge or in bulk. Applications are similar to those of the polysulfides, including the insulated glass markets and sealing automotive windshields. 

Robots are used to dispense adhesives and sealants throughout the automotive industry today. Automation requirements will be examined for windshield bonding to the vehicle, door manufacturing, passenger compartment interior seam sealing, and the application of sealants during the buildup of the vehicle body. These account for the vast majority of robotic sealant and adhesive dispensing applications in the automotive industry. 

Figures 13 and 14 depict possible robot system configurations for windshield bonding and body shop sealing. All of the applications mentioned have similar considerations for evaluation of robotic applications. The common considerations for robotizing these and other adhesive and sealant applications include required bead profile (round, flat, or triangular) instantaneous flow or delivery rate robot speed, accuracy and repeatability and workspace of the robot.

Butyl rubber tapes are also used in automobiles for the glazing of windshields and back lites. Other automotive apphcations for butyl tapes and gunnable mastics are as after-seals for windows, as vibration dampening materials on panels, and as general sealants on finme and body parts. 

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