Achievements in the Field of Increasing the Thermal Properties of Anaerobic Adhesives. An Overview
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evements in the Field of Increasing the Thermal Properties of Anaerobic Adhesives. An Overview D. A. Aronovich* Kargin Polymer Research Institute, Dzerzhinsk, 606000 Russia *e-mail: [email protected] Received February 28, 2019; revised March 28, 2019; accepted April 1, 2019
Abstract—This review examines advances in improving the thermal properties of anaerobic adhesives and other functional characteristics. Keywords: adhesive, sealant, anaerobic, oligoester acrylate, oligourethane acrylate, locking of connecting thread, fixation of cylindrical connections DOI: 10.1134/S1995421220040024
INTRODUCTION Anaerobic adhesives (AAs) are widely used in industrial production for bonding and sealing various metal joints. The world volume of AA consumption in 2017 is $429.5 million (~5000 t). Further growth in AA consumption is forecast, and by 2022 it should amount to $564.1 million with an annual increase of about 5.6%. The greatest demand for AAs is expected in automotive and transport engineering [1]. A distinctive feature of acrylic AAs is the ability to cure at room temperature in narrow gaps of metallic parts that are difficult to be access by air oxygen, which, as is known, inhibits radical polymerization. AAs have a complex of valuable properties: —single-component when applied; —no solvents; —long-term viability in air-permeable containers (more than 1 year); —high permeability; —wide choice of viscosity; —fast cure at room temperature; —high strength characteristics; —resistance to fuels, oils, antifreeze, weak acids, and alkalis; —wide temperature range of operation; —possibility of automatic dosing; —ensuring a high degree of tightness under pressure and in vacuum when exposed to liquid, gaseous media, vibration and impact loads. The main purpose of AAs is related to their capability of curing in a narrow gap between metal substrates, namely, locking (locking) of a connecting thread, sealing of flanges, flange and pipe threads, fixing the cylindrical connection, sealing of casting, and welded seams and parts of powder metallurgy and structural bonding. AAs were first obtained by R.E. Burnett and B.W. Nordlander in the early 1950s based on polyeth-
ylene glycol dimethacrylate [2]. However, the first AAs were not technologically advanced and required the constant introduction of air into the oxygen composition to ensure viability. Vernon K. Krieble modified AAs by adding hydroperoxides and further decomposition promoters thereof [3]. Later, Robert H. Krieble patented a method of stabilizing AAs by introducing small amounts of quinones into the composition [4]. American Sealants Corp. was founded to produce AAs, and then did Loctite Corp. In 1997, Loctite was acquired by Henkel AG [5]. Currently, research centers and industrial production of AAs exist in many developed countries. In Russia, research on the creation of AAs was begun in the 1960s, the history of their development is described in article [6]. Since the creation of the first world’s first AA, hundreds of patents have been obtained for composition
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