Chlorosulfonated polyethylene acrylic adhesives

These are all examples of soluble polymers. Combinations of soluble with insoluble polymers have also been reported. Polychloroprene or chlorosulfonated polyethylene was eombined with core-shell polymer particles to give an adhesive with improved cold impact resistance [33]. The fascinating chemistry of chlorosulfonated polyethylene in acrylic adhesives will be further discussed in the section on initiators. In many cases chlorosulfonated polyethylene is chemically attached to the acrylic matrix. 

A technology developed at Du Pont75 combines the use of reactive sites on the oligomers with the initiation reaction. The resulting family of acrylic structural adhesives has become popularly known as second generation acrylics. They consist essentially of solutions of chlorosulfonated polyethylene (Du Pont Hypalon ) in acrylic or methacrylic monomers. The chlorosulfonyl groups present on the polymer will react with... 

During the last decade many new roofing materials were introduced which are applied in the form of weldable membranes, liquid curable materials, self-adhesive products, and torchable materials. These materials are produced from numerous polymers such as, PVC, chlorinated polyethylene, chlorosulfonated polyethylene, EPDM, acrylics, bitumen, polymer-reinforced bitumen and several other materials. It is beyond the scope of this book to analyze compositional changes in these materials. We will provide a brief overview. 

Acrylic structural adhesives have been modified by elastomers in order to obtain a phase-separated, toughened system. A significant contribution in this technology has been made in which acrylic adhesives were modified by the addition of chlorosulfonated polyethylene to obtain a phase-separated structural adhesive (11). Such adhesives also contain methyl methacrylate, glacial methacrylic acid, and cross-linkers such as ethylene glycol dimethacrylate [97-90-5]. The polymerization initiation system, which includes cumene hydroperoxide, IV,AT - dimethyl-p- toluidine, and saccharin, can be applied to the adherend surface as a primer, or it can be formulated as the second part of a two-part adhesive. Modification of cyanoacrylates using elastomers has also been attempted copolymers of acrylonitrile, butadiene, and styrene ethylene copolymers with methylacrylate or copolymers of methacrylates with butadiene and styrene have been used. However, because of the extreme reactivity of the monomer, modification of cyanoacrylate adhesives is very difficult and material purity is essential in order to be able to modify the cyanoacrylate without causing premature reaction. 

Prane (11) reviews the field and concentrates on history citing pivotal patents related to acrylics (or reactive ) adhesives. These patents show that numerous materials have been utilized in toughening acrylic adhesivesr some nonreactive in the systems, others reacting in, while still others using combinations of each general type modifier. Thus, we find examples for polychloroprene, thermoplastic urethanes, urethane adducts, acrylic rubber, chlorosulfonated polyethylene in addition to buta-diene/acrylonitrile rubber (or its carboxylic version). 

Chlorosulfonated polyethylene can used in reactive adhesives in combination with (meth)acrylate monomers and also in rubber-to-metal bonding agents. 

Another important part of stmctural acrylics is the toughening agent. As with epoxies (vide supra), acrylic adhesives would be brittle materials without the addition of a toughening agent. Chlorosulfonated polyethylene has already been mentioned as such a material. Other materials include polyurethanes that have been end-capped with methacryloyl end groups as well as other materials such as core-shell tougheners. 

Extension of the chlorosulfonation technology to base resins other than polyethylene, where value can be added, seems a logical next step. Polypropylene and ethylene copolymers containing additional functionaUty, ie, maleic anhydride graft, vinyl acetate, acrylic acid, etc, have been chlorinated and chlorosulfonated to broaden the appHcation base, particularly in coatings and adhesives (9,10). 

Although the base resin is usually polyethylene, other base resins, ie, polypropylene (6), ethylene propylene copolymers (7), and polymers containing additional functionality (ie, vinyl acetate, acrylic or methacrylic acid, and maleic anhydride graft) have been chlorinated and chlorosulfonated commercially. This family of polymers is widely used in rubber and adhesive industries because of the valuable properties that can be achieved when properly compoimded and vulcanized. 

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