Epoxy Adhesive as Steel Glue

Epoxy adhesive can be applied in many thing, use in metal or in plastic. Epoxy compounds are designed withstand to exposure and hostile environmental condition. This adhesive can be applied in craft, automobile, optical, medical, chemical process, electronics and many other industries. Some epoxy adhesive products can be formulated to meet specific application requirements.




Epoxy Adhesive as Steel Glue can available in two kind product system:

• One component epoxy glue
• Two component epoxy glue

Epoxy Steel glue one component have latent curing to make this glue can be kept in tube or in other kind of packing. This steel glue already mixed with hardener but by adding some solvent for this mixing make this mixing are not reacted. After the solvent is vapor epoxy resin and hardener will react as usual become hard compound use as steel glue. Steel glue in one component is more simple to use, no need to formulate first or mixing first. Steel glue in one component can be provide in liquid, paste, and solid forms. Curing system of this steel glue may use UV or heat curing system to make steel glue meet the static composite.

The use of one component steel glue system

Steel glue one component can be applied in aircraft, electronic, medical, electrical, automotive and optical industries. Steel glue in liquid and packing using tube can be used easily to glueing electronic part or in confined place. After gluing material using steel glue singgle component some treatment need to do in order make curing of steel glue work.

• Mostly one component steel glue need heating at temperature 125 to 150 oC to make the solvent vaporized then to cure the epoxy resin.
• Other type of steel glue can be cured at lower temperature to cure (80 – 100 oC), for this process need to read on the procedure of steel glue to use.
• For B-stage epoxy system, steel glue can beginning to cure at room temperatures and fully cured at higher temperature.
• Some product need UV light curing epoxies, the reaction is activated by a suitable light source at the proper intensity and wavelength.

Two component Epoxy Adhesive as Steel Glue

Two component of epoxy steel glue contain of resin part and epoxy hardener part, this two part must be formulated to make a single mixture then use to glue steel you want to. This two component epoxy steel glue can be applied in mechanical, thermal, optical and electrical purpose. Mixed ratio of resin and hardener can differ, depend on how fast you want to cure, at ambient temperature or at elevated temperature for faster cured.

The Advantage of Two component steel glue

• Resistance to abrasion and shock
• Ability to withstand at thermal cycling
• Fast cured at ambient temperature
• Gap filling capability
• Exceptional adhesion to similar and dissimilar substrates
• Uniform stress distribution
• Long term durability
• Easy application
• Solvent free formulation
• Dimensional stability

Other kind of Steel Glue:

• Phenolic Epoxy Adhesive
• Metal Adhesive
• Gluing Metal to Metal
• Wood to Metal Adhesive

The strongest Steel Adhesive

We often use steel adhesive not just for steel but also for other goods, such as for plastic and other purpose. Steel glue is different with UF glue that commonly for wood adhesive. For plastic also have either type of glue you can use power-glue or super-glue. If you use glue that is not designed for certain goods, the result will not satisfied. The best steel glue is not just the strongest stick to the plate but also must stick faster. Some steel adhesive too long dry, I have used this and waiting for dried, this too long to dry. I have waiting for 2 hours but still wet and finally let it until tomorrow. A pity when I check it again after 12 hours this glue still wet. This is not good steel adhesive. If you go to Supermarket, you will meet many trade mark of steel glue available there but you must be careful because not of all steel glue have good quality.

Steel Glue

One of steel glue that already test the quality and strong is Dextone. Dextone is one of Epoxy Adhesive type. This glue already use for patching up the fuel tank of my truck, and already two years still in good condition, whereas previously already tried by welding, and can’t work. I don’t discredited other trade mark but this steel glue already use by many people and usually they have good comment about this product. This steel glue just need to dry after 1 to 2 hours, it is depend on your mixing between glue and hardener.

On this steel glue have two kind of chemicals that usually keep in tube, one have black package and the second is in white color package. I usually mixed fifty fifty, half for black paste and half for white paste. It depend on your needed how much you need the glue will use. After you mixed both paste and as soon as you use this mixing, because the left will hardened fastly, and you can’t use this.

Epoxy Resin Hardeners

Epoxy resin will cured with high strength plastic soiled at room temperatures, by mixing specific proportions of liquid epoxy resin and hardener. Highly moisture resistant plastic adheres to a wide range of materials, and this properties ideal for projects that required water and chemical resistance and strong physical properties and structural bonding.

The strength of this adhesive depend the kind of hardener use, better hardener and suit composition will get best strength and good physical properties after curing. Type of hardener for Epoxy resin like HN-2200, HN-2000, HN-5500 and MHAC.

Alicyclic acid anhydride type have less toxicity, a longer pot life and lower exothermic characteristics in comparison with amine type hardeners. Applications of these epoxy resin hardeners extend to casting, impregnation, lamination and many others.

How to use:
- Liquid hardeners easy to mix with epoxy resins
- Less toxicity than amine type hardeners
- Epoxy resin compounds available a long pot life
- Cured epocy resin compounds available excellent heat resistance by being cured with MHA.

Sample product of Epoxy Resin and the hardener as follows:

See Other Epoxy Resin Hardener:

Araldite Epoxy Adhesives

Araldite from epoxy adhesive have good strength due to superior of two part epoxy adhesive technology. Araldite epoxy adhesives provide a rigid, durable bond for a wide range of surface and can be used for some gap filling.

In several plant araldite use to cover of floor from corrosive chemicals, to stand more longer from damage. There are several kind or araldite epoxy adhesive purposes, each kind of araldity adhesive type has certain characteristic depend on the goal of using the adhsive.

Very Fast Setting Araldite
Epoxy Adhesive A very fast setting two part epoxy adhesive. Initial bonding achieved in 90 seconds with maximum bond strength after 16 hours.

Fast Setting Aradite Epoxy
Adhesive A fast setting strong and durable two part epoxy, general purpose adhesive. Mixed product gels in 5 minutes. Initial bonding is achieved in 20 minutes with maximum bond strength after 16 hours.

Araldite Epoxy Adhesive Super Strength
A two part epoxy adhesive that bonds with maximum strength. Mixed product gels in 2 hours. Initial bonding is achieved in 6-8 hours with maximum bond strength strength after 3 days.

Strong and Durable Araldite Adhesive
A strong and durable, fast setting two part epoxy adhesive that dries crystal clear making it ideal for areas where an invisible bond is required. Mixed product gels in 5 minutes. Initial bonding is achieved in 20 minutes with maximum bond strength after 16 hours. Weather and yellowing resistant. Shock resistant.

Araldite Self Mixing Adhesive
A high-strength 2-part adhesive that uses Fusion Technology and comes with an easy to use self-mixing syringe and precision applicator No need to squeeze & mix, as the advance nozzle mixes the epoxy for you! Instead, Araldite Self Mixing can be applied directly to break or surface requiring bonding leaving you with a no-mess application. Includes two self-mixing nozzles

Araldite Sealant Fusion Adhesive
Provides the strength and durability of Araldite with the convenience and easy application of Supa Glue. For strong bonding in 90 seconds, just point and press.

Gluing Metal to Metal

As metal to metal glues the polyurethanes are inferior to epoxy resin adhesives and to the best two polymer adhesives. Test on aluminum alloy using a number of polyurethane systems based on tolylene diisocyanate and saturated polyesters have shown the highest tensile shear strength that can be obtained is less than half that given by the best epoxy resin and two polymer adhesives when cured at 150oC. The strength of hot-cured metal to metal joints can be markedly improved by incorporating a relatively high proportion (up to 25%) of polyvinyl butyral, or formal, with which tolylene diisocyanate is compatible; peel strength, not usually very good is polyurethane adhesives is also substantially increased by such an addition. Increasing the proportion of polyester, thereby again increasing the flexibility also improves peel strength, but at a point where the gain becomes worthwhile a decrease in shear strength inevitably follows.

In examining as an adhesive for aluminum a polyurethane based on a triisocyanate and hydroxylated polyesters, it was found that the polyester having the lowest hydroxyl content gave the strongest bonds. This is rather surprising, but since the bonds were also reported to lack water resistance, it is interesting to consider whether the adhesive system contained hydroxyl groups in excess of the isocyanate requirement.

In a study of the effect of the ratio of molecular weight to isocyanate and others compared the adhesive strength of MDI and TDI. Using the same polyol mixture, it was bound that at room temperature (about 24oC) both systems had approximately equal maximum tensile shear strengths of about 5,300 psi, which is quite surprisingly high. But below this temperature the MDI system was considerably better (test made on aluminum): at -730C, for example, the MDI system had strength of 5,100 psi as against 3,900 psi for the TDI.

Because the polyurethane resins can be foamed in situ and adhere to metal their use as the core material in sandwich construction is of possible interest. Fabrication is not difficult, but the polyurethane having low moduli of elasticity compare unfavorably, for example, with aluminum honeycomb as a sandwich core material.

See the different adhesive Resin and Plastic.

Metal Adhesives

In many applications, such as in gluing metal to wood, a metal forms only one adherend; one extremely important example is the bonding of brake and clutch linings to metal. This application was one of the first to be investigated when epoxy adhesives became available, and although they are perfectly satisfactory, they are not used on anything like as large as scale as the two polymer adhesives based on phenolic/polyvinyl acetal systems.

Some specifications dealing with metal adhesives for aircraft structures demand resistance to variety of chemicals, and to salt solutions. The chemical resistance of bisphenol A adhesives depend on the curing agent and the curing cycle; it is therefore possible only to generalize by saying that epoxy resin have good resistance to acids and alkalis, to all alcohols and most hydrocarbons, but are somewhat sensitive to the lower ketenes. In many adhesive applications resistance to water is the most important requirement, and this is affected by the thickness of the glue line and nature of the adherents, as well as by the composition of the adhesive system. In a study of the chemical resistance (not in adhesive applications) of three types of hardener, anhydride, amine and boron trifluoride complex, it was shown that dimanodiphenyl sulphone gave the best chemical resistance and the best resistance to boiling water.

Fatigue, creep and impact resistance are important factors in aircraft adhesives, and these properties are obviously dependent on the hardener used and on the incorporation of additives especially flexibilisers. Specific information is available relating to the fatigue behavior or this adhesive generally. The creep resistance of glued metal joints has been included in a comprehensive paper by Hans.

The strength of epoxy adhesives shown extent to which this property can be improved by the addition of the polyamide Versamid or polysulphide Thiokol. The effect of asbestor on impact strength has been referred to under fillers.

Here it is appropriate to emphasize again the fact that unless accompanied by complete data such as type of metal, type of joint, curing temperature etc., the "bond strength" of an adhesive has only limited meaning. The result of detailed test can, however, be obtained from a number of sources, apart from some already noted.

Epoxy adhesives in film, on a carrier such as glass fiber, are specially suitable for bonding the skins to the honeycomb core in the making of sandwhich constructions. One advantage is that an adhesives can be formulated that has just the right amount of flow to enable good filleting to be achieved on the vertical edges of the honeycomb. This is an application where an asymmetric film is especially useful.

Bisphenol A Epoxy Adhesive Properties

Properties and Applications of Bisphenol A Epoxy Adhesives

These are only a few materials that bisphenol A epoxy resins will not bond satisfactorily, the chief ones are polyethylene, polypropylene, polystyrene, polyfluorocarbons, and silicone plastics and rubbers. Even in the case of these exceptions, a satisfactory measure of adhesion can be obtained by specially treating the surface, which usually means that one is eventually sticking to a rather different substance. But the properties of the adhesion in the glued joint, as well as the adhesion to a particular adherend depend on the whole adhesive composition, that is to say, on the type of resin, the curing agent, fillers and modifiers. Equally, the properties of the adhesive become completely meaningful only when related to a particular adherend in a particular use; it is however impossible to assemble all the relevant data.

Wood
Wood is by far the world’s most commonly glued material, but there is little information on gluing it with epoxy resin. This is not surprising because there is not a strong case for using it to glue wood, other resin adhesive generally do the work better at lower cost. However, no doubt some applications have been found for which epoxy adhesive are especially appropriate.

As one would expert with the use of a glue that is water insoluble when applied, the moisture content of the wood is more critical than when using, say, a urea formaldehyde adhesive. The water resistance of wood joints glued with bisphenol A resins is a matter in which variable experience is reported. Clarke and Nearn examined a number of parameters that effect adhesion and were of the opinion that it was not possible to obtain water resistant bonds, at least not on maple with the adhesive system they used. Obviously the adhesive system is important, the type of hardener being more important than supposed. The type of timber certainly has an effect, especially on hot-water resistance; an example of the difference between birch and beech is shown below, in the strength of hot pressed plywood joints using diethyl aminopropylamine as hardener.

Birch: Strength; 506 lb (all wood failures), Wet Strength; 519 lb (all wood failures)
Beech: Strength; 370 lb (all wood failures), Wet Strength; 0 lb (all wood failures)

The Curing of Bisphenol A Epoxy Resin

As all users of bisphenol A epoxy adhesives will know, the uncured (solid) resins have low mechanical strength, and by themselves are of little value simply as hot-melt adhesives. It is only when cured that they make really useful adhesives.

The valuable polymers are those by reaction with crosslinking substances, referred to as accelerators strength, curing agents or hardeners. Certain polymerization catalysts, in conjunction with curing agents, sometimes have a use in adhesives.




The normal method of crosslinking epoxy resins entails a resinification reaction whereby molecular growth takes place throught the linking of dissimilar molecues which, as in the case of the polyurethanes, involves a poly addition reaction with compounds having active hydrogen atoms.

There is, of course, no difference between the curing of an epoxy resin for adhesive use and any other application; nevertheless, one or two curing agents appear to be especially good for loading certain materials, in particular dicyandiamide for the bonding of certain metals.

If the curing agent is a substance of high molecular weight, or more correctly, if its equivalent weight is high with respect to the functional groups involved, a large mass of it will be required to cure the resin; the cured product will therefore contain a large percentage of it, perhaps more than one half. As a result, the mature of the curing agent itself will be built into the final resin molecule and contribute its own part towards physical (including mechanical) and chemical properties. Thus the subject of curing agents is at least as important as the subject of epoxy resins themselves.

As well as the physical properties of the curing agent, the number and the arrangement of its functional groups is important; on these depend the nature and speed of the reaction with the epoxide groups, the nature of the cured polymer, its hot-strength and so on. Equally of course, the epoxy compound itself has a similar influence. Collectively, a number of factors determine the properties of the cured resin; the functionalities of the epoxide and the hardener, the nature of the functional groups of the hardener, the overall structure of both the epoxy resin and the hardener molecules, and the ratio of hardener to resin.

Bisphenol A Epoxy Adhesive

The bisphenol A. Epoxy adhesives stick to most things, and are probably the most versatile of all high strength adhesives. Since the time the early nineteen forties when the commercial importance of epoxy resins became recognized in Switzerland and the USA, an enormous number of patents has been taken out relating to their composition and use; while most of these patents do not deal specifically with adhesive use, many embrace it in a general way. Also numerous papers and three or four books have been published on the subject of epoxy resins and their applications.

Among the early patent are those of Trey Fretes, and Ciba of Switzerland, and Devoe & Reynolds and Shell of USA. Some of these describe use as adhesives while others relate to methods of preparing the resin and hardening it, the glycidyl compounds themselves having been described some years earlier.

Preparation of the Glycidyl Compounds

By reacting epichlorohydrin with a substance having a molecular structure containing replaceable hydrogen atoms such as hydroxyl group, a glycidyl ether R-O-CH2 -CH-O-CH 2 may be obtained, the glycidyl compounds of bisphenol A are the outstanding examples. The molecular structure of this is commonly represented as complete formula that is shown aromatic structure.

The monomeric diglycidyl ether, for which the value of n is 0, is of lower viscosity than higher members of the series, although if sufficiently pure it may be a crystalline solid. As the value of n increases the resin becomes progressively, a more viscose liquid, a solid of low softening point, and a solid of high softening point. The special advantage of a liquid (solvenless) adhesive needs no emphasing; nevertheless, the solid polymers also make useful adhesives, they are in fact together but they are in fact tougher but have lower hot-strengths.

Curing Agents of Epoxy Resin

Epoxy adhesives comprise a liquid or a fusible solid containing epoxies groups, and a curing agent containing functional groups with which the epoxies groups combine to form a cross linked polymer. A type of so-called curing agent, of little importance in adhesive, is that which catalyses homo polymerization of the epoxy compound.

When the reaction between resin and hardener is capable of taking place at room temperature the two component are mixed immediately before use, but if the mixture is relatively inactive under ordinary storage conditions the components may be mixed together and marketed as a 'single package' adhesive. The 'B-stage' adhesive systems also comprise a single component, but in this case the resin and hardener have been reacted to an intermediate, but still fusible stage.




The curing that takes place when the resin and hardener are brought into intimate contact, for example be melting the solid under appropriate conditions, is an irreversible reaction that result in a thermoset resin. This reaction does not involve condensation polymerization and therefore no low-molecular weight substance such as water is split off. For this reason the shringkage that takes place during cure is slight, and this is one of the properties that makes epoxy resins especially valuable as adhesives. Furthermore, a wide range of end products having a correspondingly wide range of properties can be obtained by use of different resin/hardener adhesive systems.

Epoxy Resin Adhesives

The development of epoxy resins has been directed towards many different field of application, one important application being adhesive bonding. It follows that much of the information which is available does not relate specially to adhesive use, but at the same time can't be separated from it; this, as will be seen from the follow article, applies particularly to methods of curing.

In the unhardened state the chemical structure of an epoxy resin (less well known also as an ethxyline resin) is characterized by the epoxy group.

---C-O-C---

There are two broad methods of adding an epoxide group in the preparation of epoxy resins or epoxy compounds leading to resins. In the first method a substance already containing an epoxide group such as epichlorohydrin (or other epihalohydrin) is reacted with a substance having repleacable hydrogen atoms, and in the second, peracitic acid (or other appropriate oxygen-donating compound) is used to effect epoxidation of an olefinic compound. The product of the first method is a glycidyl compound, which in the most important cases is a glycidyl ether, amine or ester. The glycidyl ether include the bisphenol. A epoxy resins, the type that is usually mean when reffering to epoxy resins in
a general way.



In view of the much larger scale on which the bisphenol. A resins are used, especially in the field of adhesion, they will be deal with separately as Part I of this section. Part II will deal with other glycidyl resin and also with the epoxy resins produced by the second method referred to above. None of the resins discussed in Part II is at present widely used as an adhesive, but some of the polyfunctional glycidyl resins have resistance. Other types have great potentially, and after further development valuable adhesive may be evolved.

Epoxy adhesives comprise a liquid or fusible solid containing epoxide groups, and a curing agent containing functional groups with which the epoxide groups combine to form a cross linked polymer. A type of so-called curing agent, of little importance in adhesives, is that which catalylises homo-polymerization of the epoxy compound.

Phenolic Epoxy Adhesive for Metal

The adhesion to metal of unmondified phenolic resins can increased by adding an epoxy resin, in particular a bisphenol a resin, and furthermore, since this addition reduces brittleness, band strength is increased. It, however, hot strength is nor to be seriously reduced, the amount of bisphenolic, it follows therefore that the cross linking of the epoxy resin (assuming no other curing agent is added) is provided for by the large excess of phenolic resin.

Interest in phenolic epoxy adhesives first came about through the demand for adhesives with improved hot strength capable of withstanding the dynamic heat generated by fast flying aircraft. The early reports published on this type of adhesive quoted hot strengths that were clearly an advance on values attainable at that time with other adhesive systems. But the excellent result obtained on stainless steel was good, the strength on prolonged heating deteriorated much more rapidly than on aluminum alloy. Some experienced conclude that the iron catalyzed the thermal decomposition of the adhesive, the decrease in joint strength is a consequence of this.

Some observation with phenolic epoxy adhesives, bonds made on titanium, brass, copper and low carbon steel also bad low resistance to heat ageing compared with aluminum. Some improvement in the behavior of stainless steel was brought about by specially treating the metal surface or by adding 1% manganese dioxide to the resin. An increase in the heat stability of stainless steel joints could be affected by adding certain metal chelates to the adhesive.

The ratio of phenolic to epoxy resin can be varied within wide limits, but the copositions that give the best hot strength (although probably not the best heat ageing) contain at least foru times as much phenolic as epoxy resin. In some formulations that have published, dicyandiamide is also added as well as a large amount of aluminum powder.