Two Component Epoxy Resin Adhesives

The curing reaction is initiated by the admixture of compounds to the resin component as the second component B, which are called hardeners and that are able to open the epoxy triangle  

Applied Adhesive Bonding A Practical Guide for Flawless Results. Gerd Habenicht Copyright 2009 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-32014-1 

bond arms (valencies) develop to which the molecules of the hardener components can attach. Typical representatives of this group are the so-called amines  

Since several reactive groups may exist at the respective monomer molecules A and B, net-like linked polymer molecules with thermoset adhesive layer properties occur in polyaddition. Due to the various selection possibilities regarding the chemical structure of the components A and B, curing behavior can be influenced as well. Differences are made between  

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Static mixing tubes are particularly suitable for the processing of two-component epoxy resin adhesives, polyurethanes and methacrylate adhesives (A-B method, Section 4.3.3) with mixing ratios in equal shares adjusted by the manufacturer. 

Two-component epoxy resin adhesives for small-size bonded joints and limited thermal stress. 

Solvent-based adhesives, two-component epoxy resin adhesives, two-component methacrylates for assembly purposes (priming, filling, smoothing, sealing, etc.) For these applications, a multitude of so-called building/ construction adhesives is commercially available. 

Fig. 31.2 Measurement of the interfacial diffusion of hydrated ions by means of the scanning Kelvin probe on a polished iron substrate (purity 99.99%) coated with an adhesive layer about 70 pm thick (hot-curing, two-component epoxy resin adhesive with amine-based hardener) containing an aminosi-lane adhesion promoter (3-(tri-methoxysilyl) propylamine).

As an example, an iron sample was coated with a two-component epoxy resin adhesive film 70 pm thick. A circular hole of 1 mm diameter in the pure iron substrate was prepared by a milling and chemical etching process. This procedure leads to an undamaged adhesive film above the hole. The hole could then be filled with an electrolyte and pressurized to establish a mechanical stress at the interface. Fig. 31.7 shows typical potential profiles in the vicinity of the hole in comparison with the topographic profile, both measured simultaneously with... 

Two-component epoxy resin water thinned dispersions are now being used as floor sealers. They have good adhesion to concrete as well as good chemical resistance. However, the particle size of the dispersion is comparatively large (approximately 1-1.5 microns) and consequently penetration into good-quality concrete is minimal and an on-surface seal is obtained. However, with porous low-quality concrete substances, considerable binding/strengthening, etc. of the surface can be achieved with water-dispersible epoxy resin-based floor sealer. 

A typical formulation of a two-component epoxy urethane adhesive would include 100 parts of a water dispersed polyurethane resin with carboxylic... 

The (physically wetting) polyaniline primer CORRPASSIV was compared with a fast-drying two-component epoxy resin primer (Messrs. Finalin, Type 144) and a metal-reactive two-component primer with adhesion-promoting properties (Type 918). All three primers were coated with a two-component polyurethane paint (B412). CORRPASSIV, both with and without top coat, exhibited no rust formation beneath the primer. The slight undermining receded after the test, and even within the cross and scratch injuries, it was virtually impossible to detect any corrosion. 

Epoxies. Epoxy resins can be formulated with a wide range of properties. These medium- to high-priced resins are noted for their adhesion, make excellent primers, and are used widely in the appliance and automotive industries. Their heat resistance permits them to be used for electrical insulation. When epoxy top coats are used outdoors, they tend to chalk and discolor because of inherently poor ultraviolet light resistance. Other resins modified with epoxies are used for outdoor exposure as topcoats, and properties of many other resins can be improved by their addition. Two-component epoxy coatings are used in environments with extreme corrosion and chemical conditions. Flexibility in formulating two-component epoxy resin-based coatings results in a wide range of physical properties. 

Uses. Applied as a powder coating, nylon provides a high degree of toughness and mechanical durability to office furniture. Other polyamide resins are used as curing agents in two-component epoxy resin-based primers and topcoats, adhesives, and sealants. 

A two part epoxy resin adhesive to bond a wide variety of materiais in addition to composites. Cures rapidly in 5 minutes to give handling strength. Packed into a handy EDS cartridge which provides metered and mixed adhesive directly onto the components to be bonded. Typical service temperature is -55 to +100 C, but 200 C can be tolerated for short periods if the adhesive is not unduly stressed. 

Recently it has also been shown that modified spherical nanosilica particles can be used to toughen epoxy resins without the loss of other properties, such as glass transition temperature or modulus.28 When such surface modified nanoparticles are added to CTBN toughened epoxy resins, the performance of both one- and two-component epoxy adhesives was greatly improved. 

ATBN liquid polymers cannot be mixed directly into the epoxy resin component of a two-part epoxy adhesive or in a one-part adhesive since crosslinking and shortened shelf life will result. ATBN adducts are, therefore, mixed with the curing agent component of two-component epoxy adhesives.30... 

They are polyamide resins with amine functionality and lower viscosity. These curing agents are used in standard two-component epoxy adhesive systems that cure... 

Designed for epoxy resin systems, Anquamine 401 and Ancamide 2424 (by Air Products) are a modified aliphatic curing agent at 70% solids in water for waterborne two-component epoxy coatings and a modified polyamide curing agent for liquid epoxy resins in two-component structural adhesives. 

Epoxy resin Adhesives. Epoxies [47], [48] are among the most widely used structural adhesives. These chemically reactive systems include two-component systems that cure at room temperature or elevated temperature and one-component systems, which usually require heat for curing. 

The pretreated polyolefins can be bonded with contact adhesives, epoxy resin adhesives, one- and two-component polyurethane adhesives, and hot-melt adhesives. 

Polyamides are bonded with concentrated (ca. 85%) formic acid. Two-component polyurethane or epoxy resin adhesives are suitable for bonding to metals, for example, for holding bearing bushings in place. 

Prefabricated Construction. Sandwich elements are widely used in prefabricated construction. In this case, bonding must meet stringent requirements with regard to stability and durability, especially in the case of exterior wall elements. Deflections attributable to difierential temperature or moisture-induced expansion or contraction can amount to as much as 5% of the length. The adhesive layer must be permeable to water vapor or act as a water barrier, depending on the structure and function of a given element. The adhesives used are two-component reactive resins, based mainly on epoxy resins, but polyurethane resins are used as well, as are elastomer-based contact adhesives that are applied on both sides. 

Iwo-component adhesives that are used for household applications differ quite strongly as to their properties. For instance, there are epoxy resin adhesives that are very well suited for bonding glass, china, ceramics and metals. They set ss-clear, are dishwasher-safe, and therefore exceptionally well suited for repairing dishes or similar household articles. Usually, the two components resin (epoxy) and hardener (amine or mercaptan) are filled in aluminum tubes or plastic double syringes and are mixed before application according to the directions for use. Other two-component adhesives are based on meffiacrylate and contain a powder hardener (dibenzqyl peroxide in gypsum). These adhesives bond materials such as stone, plastics, ceramics, and metal ... 

The epoxy resin and hardener are kept separated in the two components of the adhesive but the other components can be formulated into either portion to adjust the viscosity and help in adjusting the mix ratio of the two components. 

A two-component epoxy system consists of a resin and a hardener, along with possible additives such as accelerators, reactive diluents, resin modifiers, plasticizers, and fillers. Typical hardeners include aliphatic polyamines, which cure at room temperature or at slightly elevated temperatures polyamides, which provide flexibility and are widely used aromatics, which are solid and anhydrides, which require elevated temperature cure and produce thermally stable but brittle adhesives. Low molecular weight epoxies are liquid and are usually cured by amines, carboxylic acid anhydrides, and Lewis acid and base catalyst. Higher molecular weight epoxies are cured through their hydroxyl groups. Cure of epoxies involves an exothermic reaction. 

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