Urea Formaldehyde Adhesive

Thermosetting Resin Adhesive

Article Contents:

Thermosetting Resin Adhesive Melamine Formaldehyde Adhesives Urea Formaldehyde Adhesive Urea formaldehyde as Wood Glue Experience on Using Urea Formaldehyde Wood Glue Product

A thermosetting synthetic resin is one that on curing undergoes an irreversible chemical and physical change to become substantially infusible and insoluble. After curing the form of this resin or adhesive can't be back into the beginning. The term thermosetting is applied to the resin both before and after it is cured. It is not a good name because it implies only a relationship between temperature and curing.




Some thermosetting adhesive are condensation polymer and some are addition polymers. The important examples are urea-, melamine, phenol- and ressorsinol-formaldehyde adhesive, epoxy, polyisocyanate and polyester adhesives. They will be considered in that order.

Melamine Formaldehyde Adhesives

Beside of Urea Formaldehyde there are many other form compound from formaldehyde reaction such as Amine Formaldehyde or Melamine Formaldehyde. Although a number of amines condense with formaldehyde to produce resinous substances, reaction products from two only are of importance as adhesives, those from urea and those from melamine. The former, marketed many years earlier and used on a much larger scale, will be discussed first

Urea Formaldehyde Adhesive

A urea formaldehyde resin or glue (also commonly called a urea glue or a UF) is the condensation product of unsubtituted urea and formaldehyde. Thiourea is not included, resin from thiourea are of negligible importance as adhesive. Urea formaldehyde have chemical formula as C₂H₆N₂O₂

General purpose of urea formaldehyde applied for wood glue such as on plywood, veneering and assembly gluing. The urea formaldehyde reaction in its relation to the preparation of an adhesive. The normal ration on reaction to form a glue use usually the molar ratio of 1U : 1.75 – 1.9 F, and rarely above 1 : 2 for the manufacture of wood particle board a somewhat lower is often used in order to keep the smell of formaldehyde to a minimum. A Rusian paper suggests the best molar ratio to be about 1:1.65, which is lower than that generally used except for making particle board, in the work referred to, a number of parameters were examined, unfortunately without relating them to the strength of glued joints.

In deciding the ratio of formaldehyde to urea, a compromise is sought between certain properties of the resin, a compromised that influence the method of manufacture of the resin solution. A high molecular ratio of formaldehyde to urea, for example exceeding two to one, result in a product having certain advantages as well as certain disadvantages. Among the advantages are increased stability in solution, and increased water-toleration or even infinite true solubility. Chief among the disadvantages is, firstly, a higher sensitivity to atmospheric moisture. In explaining this it should be understood that all uncured urea resins are to some extent hygroscopic; most powder resins have an equilibrium moisture content at between 60 % and 70 % RH, that is to say they neither absorb nor lose moisture at some relative humidity within these limits at a normal temperature.

Urea formaldehyde as Wood Glue

Urea formaldehyde as wood glue have characteristics such as low cost for huge application, low cure temperature, resistance to microorganism and also abrasion, Light color. But urea formaldehyde as wood glue have disadvantage like rapidly deteriorate if any hot solution is splash to this glue, easy to release formalin from their component. Another type of wood glue can use epoxy resin that more prefer by consumerist because have good characteristic like good gap filling, resistant to salt water, and heat resistant compare to urea formaldehyde as wood glue. So epoxy resin can stand longer in tropical climate which is often rain and make high humidity environment.

Experience on Using Urea Formaldehyde.

Urea formaldehyde on resin form still don't have strong stick of two wood, this resin need a filler and hardener for gluing application. So for carpenter that is use this kind of resin usually will get a guide first from the vendor, even they don't learn on using this glue, they still have a good result after gluing their wood product. Urea formaldehyde also already sold in many material shop together with filler and hardener so you can use easily now.

See form of Urea Formaldehyde Powder as result of experiment:

Urea Formaldehyde Powder

Wood Glues Product

There are many wood glue are sold in the market, you can choose what is the best product as the experience of people. Wood glue also provide in many package, you can choose as you need.

wood glue

See many other glues:

Wood Glue Product

For industrial uses, wood glue can use Urea Formaldehyde adhesive. Because this adhesive is simple to use, spread over the surface of wood then use technique hot press to make wood stick each others. For house hold or small industry wood glue is sell in small packing like in tube or can.

Here are some of small packing wood glue in the market:

Loctite PI Premium 28 oz Construction Adhesive
Low VOC content meet stringent Federal and state regulatory requirement. Water proof – great for interior or exterior applications. Meets and exceeds APA specification, can be applied directly to dry, wet of frozen lumber.

3M Spray Adhesive
As usual application 3M Adhesive can provide high coverage with a fast, aggressive tack. Delivers versatility by securely bonding many lightweight materials. Gives a low soak in for long lasting bonds.

Air Stone as General Purpose Adhesive
Have adhesion and flexibility. Ready to use. Exterior or interior use. No need solvent, Cover 20 square feet, using a half inch bead

Can use for cement board, brick, cementations backer units, cured Portland cement plaster, gypsum, wallboard, exterior grade plywood, glass, PVC, aluminum, well cured concrete, galvanized steel, stainless steel stone and marble.

PC Products Epoxy Adhesive
Epoxy system for several rotted wood, hardens to near structural strength, mix and apply with pour bottle that is included, waterproof upon cure, use prior to rebuilding with PC-Woody paste epoxy.


Other Site:

• Electroplating Page
• Anodizing Step by Step
• Adhesive Content

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 Application and Properties of Resorcinol Glue

In their application, the resorcinol and resorcinol/phenol glues are considered to be slightly more sensitive to ambient conditions than many other adhesives; the reason is the previously mentioned tendency to rapid drying-out. In conveniently rapid drying-out of an adhesive creates difficulties in spreading and reduces assembly time.

Cured resorcinol and resorcinol/phenol adhesives are known to withstand exposure that are in fact less detrimental to the glue than to most timbers. As assembly glues for wood they comply with the highest requirements of all specifications, including resistance to boiling water. They have acquired a reputation for making laminated beams and other load bearing structures used in buildings.



In dealing with performance of resorcinol adhesives it is usual to consider glued joints that have been cured at ambient air temperatures. With this in mind the following extract from a report is of interest; 'the durability of well-made phenol/resorcinol, and resorcinol resin glue joints, based on about 16 years experience, appears to be eventually equal to that of hot pressed phenol resin glue joint.

In order to obtain maximum durability in a wood glue component, the use of a preservative treated timber is essential and question of glueability therefore arises. In spite of the different nature of the substances used to impregnate timber, it may be conclude that, with certain qualifications, preservative treated timber can be glued satisfactorily with a resorcinol glue.

The use of resorcinol adhesive is not confined to wood. There is, however, little published information on their behavior with other adherents. Although they have been used for gluing metal, they can't in any way be considered as important metal adhesives. In metal to wood construction they have generally been successful for a number of years a resorcinol glue was used for bonding aluminum alloy sheet to ash framework for the roofs of London buses.

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.

Make Plywood

plywood

If you buy new cupboard may you meet with this material. Plywood become prefer furniture industry as raw material of their product to produce furniture. Actually there are some quality of plywood as raw material of furniture, but for cheap price they will use bad quality of plywood. Low grade of plywood usually use for structural purpose like roof sheathing. High quality plywood actually use as paneling, furniture and cabinet. The quality of plywood it self divide into 4 grade from grade A to D.

Plywood material also can be from several source such as soft wood and hard wood. Soft wood have longer fiber than hardwood. Soft wood source are fir, pine, cedar, spruce and redwood tree. Softwood also as raw material of viscose fiber industry, while hardwood usually just can use for raw material in paper industry.

To make plywood can be produced from either saw dust or wood ply, wood ply is made by slicing wood in wide size. This raw material then mixed with wood glue like urea formaldehyde or epoxy resin. For wood ply is just add glue at all surface then coupled and press. After gluing all surface, then wood ply is press with hot plate to make fast dry.

Other Site:

• Electroplating Page
• Anodizing Step by Step
• Adhesive Content

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)

Wood to Metal and Wood to Wood Adhesives

There is a stronger case for using an epoxy resin for gluing wood to metal than wood to wood. For wood to wood gluing using wood glue or Urea formaldehyde resin, that already impregnated with certain hardener. Clearly a curing temperature of 40 ^oC is insufficient for diethylaminopropylamine.

Metal Gluing

The most important adhesives use bisphenol A epoxy resins if the gluing of metals. All the common metals (and probably all the uncommon ones) can be glued, some better than others. The structurally important metals such as aluminum and steel are, fortunately, easy to bond; copper and lead are not so easy. In most cases, however, it is not the metal itself, but some oxide or other substance to which the bond is actually made.

By far the greatest amount of information that has been published deals with the adhesive strength on aluminum alloys.

Copper was the chief subject of study in one paper dealing with the effect of heat on epoxy adhesives, and it was shown that with the type of test used, the strength on copper was only about half that on aluminum.

The bond strength on aluminum including example of relationship to temperature, has been shown in earlier section dealing with hardeners.

The bonding of metal to metal in the manufacture of aircraft is the most spectacular use over made of an adhesive and still a source of some wonder. In the operation of aircraft sharp extremes of temperature may be met, extremes that can nowadays vary between -50 ^oC and more than 100 ^oC in few minutes. And whilst a constant strength within these extremes may not be demanded, something approaching it is expected.

In some operations associated with missiles, resistance to extreme cold is more important than resistance to heat. The behavior of an epoxy adhesive has been studied at – 253  ^oC; at this temperature three systems, one a nylon filled epoxy polyamide, and another a fluorocarbonepoxy polyamine composition have been stated to give food adhesive strength and toughness, (the third adhesive was a polyurethane).

Fillers and Extenders

The subject of fillers and extenders is concerned mainly with the use of phenolic glues in plywood manufacture. By applying a relatively thick layer of extended (or filled) glue, compared with a thin layer of an unextended glue, fewer glue starved areas result when coating uneven veneers in roller type glue, spreaders. This is a matter of considerable technical importance. Another is the effect of fillers in reducing absorption and penetration in the gluing of porous veneers. One of the recognized shortcomings of liquid phenolic glues cured at high temperatures is penetration. Fillers may be added to impart special rheological properties; the incorporation of filler can also facilitate spreading. Finally, there is the advantage of cheapening the flue mixture.





It has been the practice to use the terms "filler" and "extender" rather loosely and often synonymously. In considering the use and definition of these terms suggest the following: "filler" being the non-reactive component of the mixed adhesive, and usually added on the maker's instructions (presumably also by the maker), and "extender" being that added by the glue user (not necessarily with the maker's knowledge or consent). There is much to be said in favor of this distinction.

The commonly used filler or extenders are wood flour, walnut, coconut, and pecan shell flour, Soya bean flour and such cheap inorganic fillers as gypsum, powdered chalk, clays and a number of other oxides and silicates including talc. The reside from oat-hulls and corn cobs after extracting furfural is recommended, and of special interest to eastern countries is the use of ground rice husk as filler. There really is no limit to the list of insoluble substances that could be pulverized and used. One of the latest is ground plum stones.

The amount of filler that can be added -with wisdom- varies considerably it depends on density, practical size and shape; a small particle size is necessary in order to ensure a smoothly spreading mix, and a mesh size of 200 (British standard 410) is common. In the case of wood and shell flour, unlike wood flours absorb water very slowly and therefore do not cause a marked increase in viscosity during the period of the pot-life. Dried blood and starches are extenders of a different class because they are not insoluble and they are adhesives in their own right.

Objectionable as excessive additions of fillers are, the use of fillers is often technically justified –economic considerations apart. The maximum amount that may be added cannot be defined, it depends on the strength, resistance to various influences and durability required. In the manufacture of plywood, a weight of coconut shell flour to the weight of resin solids is nowadays not uncommon.

How to Use UF Powder

Urea formaldehyde (UF) adhesives are available as either liquid resins or powder form. Both will produce similar glue line characteristics: strong, rigid, thermosetting, and excellent heat resistance.
Urea formaldehyde molding powder are preferred where production runs are infrequent, where the ambient temperature is high, and where longer storage life is needed. UF powder have a one-year shelf life. This are pre-formulated should be mixed with required fillers, hardener and catalyst to meet a wide range of process requirements.

Preparation of UF Adhesive Resin

To make urea resin from UF powder, use water necessary to reconstitute the powder resin. Amount of water is about 50-65% dry weight of the dry powder to be mixed.

• Filled the container with 2/3 part of water needed to the mixing vessel.
• Slowly add the powder with stirring motor with slow speed ( < 2,000 rpm) with a mechanical agitator.
• Stirr continuously for about 5 minutes using a spatula to scrape powder from the sides back into the liquid. The mixture should be creamy and virtually lump-free at this point.
• Add the remaining 1/3 water and mix for an additional minute. Mix should be smooth, creamy, and lump-free.

To use this UF paste to the surface of wood or plywood evenly and glued together both wood to make stick each other. Press both of wood and lets it on the press condition and let it dry. Urea formaldehyde is a termosetting resing that mean this resin can cured (hard) need time and temperature. Curing time can be faster if apply in higher temparature, but it can be longer if lets this ply in room temperature.

The required condition is as follows:

• Solid wood glue-ups will require from 150 psi for low-density species up to 250 psi for high-density species.
• Cold pressing panels at 70 °F will require from 4 hours press time on low density species to 6 hours on high density species. At 90 °F this range will be from 2 hours to 4 hours.

Wood to Metal Adhesive

Adhesion in the bonding of wood to metal can be improved by adding a quantity of a polyvinyl acetal, in particular, 10-20% polyvinyl butyral; some care in the selection of solvent may be required. Alternatively, a solution of polyvinyl butyral can be applied to the metal and the resorcinol glue to the wood. The important subject of mixed thermosetting and thermoplastic adhesives is dealt with separately under the heading two-polymer adhesives.

Where the gluing of non-porous materials is concerned, it is natural to be careful about using adhesives containing much solvent especially if both adherents are non-porous. However resorcinol resins are used with great success in bonding certain plastic materials, especially melamine decorative laminates. Good results have also been obtained in bonding nylon with a resorcinol/phenol glue-results not unrelated perhaps to the solubility of nylon in phenol. As an example, the tensile shear strength obtained in bonding nylon 6 (polycaprolactam) to itself an to beech are of the order of 1450 psi and 750 psi respectively.

Resorcinol resins adhere well to concrete and brickwork, but special precautions need to be taken with concrete to achieve best results; this is because the 'laitance' (the loosely-bound surface commonly present on ordinary concrete) may be torn away through shrinkage stresses created during the setting of the adhesive. The precautions against this should include adding filler to the resin to reduce contractions, and abrading the surface of the concrete to expose the aggregate. A better way is to prevent formation of the laitance by vibrating the wet-mix in the course of laying the concrete. In other building applications, gluing to brickwork is generally satisfactory. And in gluing asbestos cement, resorcinol glues are highly successful. With asbestos cement as with concrete it is wise to allow for the reduction in shuffling time that alkalinity of cement may cause or, alternatively, neutralize the surface by applying a dilute solution of an acid.

Cylized rubber is readily glued with a resorcinol resin, especially to wood. In gluing rubber and other non-porous materials to wood, it is best to use an alcoholic, rather than an aqueous solution. Alcohol is easily to vapor and will not make adhesive wet and difficult to cure.

An important application of a resorcinol resin, although one that is perhaps marginal for consideration here, is in improving the adhesion of rubber to rayon and other synthetic fibers in the manufacture of automobile tires, a mixed resorcinol resin and rubber latex adhesive being described wherein the non-acidity and water-solubility of the former permit compatibility with rubber latex.

Hot Setting Phenolic Glues

The hot setting phenolic glues have their important place in making plywood. They are usually made with a molar ratio of about 1.5 - 2.25 formaldehyde to 1 of phenol. If prepared under weakly alkaline conditions, as formation of the resin proceeds, separation into two layers takes place an aqueous layer above. Under more strongly alkaline conditions, above pH of about 10 but depending on molecular ratio and degree of condensation, a homogeneous solution is formed, this makes the resin appear water soluble, whereas it is in fact soluble in the aqueous alkali. By comparison with pure phenol resins, cresol resins require higher concentrations of alkali to ensure solubility. Nowadays, phenolic resin plywood glues are applied mainly as aqueous alkaline solution, and to a small extent as film glues.

Of the phenolic substances that may be used to replace ordinary phenol in adhesives, mixed-isomer cresol, as distinct from meta-cresol-and mixed isomer xylenols are most used. In subsequent polycondensation of the resultant methylol phenols (the hardening reaction), further shown that the rates of polycondensation although lower are of the same relative order.

The curing of the solution form of phenolic wood glues at a high temperature say 130oC, is attended by certain disadvantages; one is the evaporation of moisture from the wood, another is the absorption of the resin by the wood, resulting in excessive penetration. The latter is influenced by the porosity of the wood and by its moisture content. So far as the glue itself is concerned there are three factors that contribute to penetration; low initial viscosity on heating, a rather slow rate of gelatin (compared with urea glue), and the fact that the resin is of low average molecular weight compared with many other polymers. The like hood of penetration is decreased as the curing temperature is lowered. It is not easy to overcome all these defects in one resin, and at the same time ensure it having satisfactory storage life.

The properties of phenol formaldehyde

Other adhesive as alternative of urea formaldehyde use is phenol formaldehyde. Phenolic glues are resistant to cold cured ones have a lower resistance to strong alkalies than the alkali cured glues, and quite naturally the converse applies; both type are resistant to all the common organic solvents. The properties of phenol formaldehyde...

Although phenolic glues are comparatively brittle, this is not a property of significant importance in many applications, for example, in plywood manufacture; nor in most wood gluing operations provided thick glue lines can be avoided. Dark color is often a disadvantage and the addition of a white pigment decreases it to only a limited extent.

Phenolic glues can be considered tolerant to most fungicidal chemicals; particular examples are sodium pentachlorophenate and isosafrole. In gluing wood, the moisture content of the timber is generally considered to be a more important factor than with urea glues. In this respect, greater latitude is claimed by dispersing, in a normal alkali condensed glue, a powdered phenolic resin condensate that is insoluble at room temperature but capable of swelling as the pressing temperature is reached.





The behavior of any type of adhesive depends in part on the material of which the adherents are made, sometimes to an appreciable extent. Durability is an important example of this. For example, phenolic metal adhesives in their operation at high temperatures are more durable on aluminum than on stainable steel, an aspect of durability that is discussed more fully in connection with the phenolic/epoxy adhesives. The durability of phenolic wood glues varies with different timbers; but factors such as glueline thickness can also have an effect. Investigations on the durability of phenolic glued wood joints have been made in England and in America.

Throughout the world the highest specifications for plywood, even if phenolic resins are not mentioned by name, are designed to make their use almost mandatory.

The Gluing of Oak

Before concluding this section on resorcinol formaldehyde adhesives, it may be of interest to mention that some users hold the opinion that the product of one manufacturer may give better results on certain kinds of timber than that of another. The author has heard this opinion expressed with particular reference to the room temperature gluing of oak. No satisfactory explanation for the behavior has been given, but the following experience suggests one, or at least throws some light on the problem.

Test pieces cut from a specimen of English oak (species not known) repeatedly give low strength when glued with resorcinol or resorcinol/phenol glue, but gave excellent strength with urea glue. The acidity of the oak was suspected to be a contributory factor; an aqueous extract was found to have a pH value of 3.7 (determined by extracting 10 g of oak in 100 ml of distilled water). It was recognized that acidity of this order might seriously prolong the gelation and setting, at least at room temperature, of a relatively unbuffered resorcinol glue. Therefore the surface of the wood was washed with a dilute solution of sodium acetate, and after this treatment adhesion with both resorcinol and resorcinol/phenol glue was excellent.




The inference to be drawn is that some resorcinol adhesives are either more alkaline than others or have a buffer capacity that enables them to resist a marked change in pH. If the pH value of the adhesive at the glue line is considerably reduced, the setting will be protected and result in so little cross linking that glued joints, even if they exhibit satisfactory adhesion initially, will have poor cold-water-resistance and poor resistance to weathering. With 'difficult' timber a higher strength can always be obtained by curing a elevated temperatures, (a corollary to which is that a boiling water test may improve the strength of a glued joint rather than reveal its weakness).

With further reference to this subject, it is interesting to note that is has been suggested that in gluing oak with a 'pure' resorcinol resin a curing cycle of 10 hours at 60 oC be used in order to give high resistance to exterior exposure (compared with 10 hours at 27 oC for Douglas fir and yellow pine).

3M Adhesives

3M Adhesives Product

3m adhesives is waterbase adhesive, this adhesive is high strength adhesive. This adhesive have benefits such as have good bonding strength and long bonding range, post formable and has good heat resistance. This adhesive has good bonding in plastics, plastic laminate, wood, plywood, wood veneer, and canvas. For adhesive that I already use, alcohol solvent is good to make adhesive dilute and your can spray it to paper or other material to use adhesive. Alcohol base adhesive .....

3M Adhesive Tape

3M Formula Adhesive

To see what the formula of this adhesive can see on the MSDS of this adhesive, this information also can copy or try for you as long as use for how to safety handing and safety application.

Weld Neoprene High performance Water Base Contact Adhesive:

Ingredients	Composition
Water Polychloroprene Rosin, polymer with phenol Glycerol Ester of Hydrogenated Rosin  Ethyl Alcohol  Xylene Zinc Oxyde  Tall Oil Rosin 2,2-Methylenebis (6-ter-Buthyl-p-Cresol)  Ethylbenzene	30 – 60 % 25 – 50 %   5 – 10%   5 – 10%   1 – 3 %   1 – 3 %   1 – 2 % 0.1 – 1 % 0.1 – 1 % 0.1 – 1 %

Fast Bond Contact Adhesive:

 

Ingredients	Composition
Water Polychloroprene Rosin, polymer with phenol Glycerol Ester of Hydrogenated Rosin Ethyl Alcohol Ethyl Benzene Xylene Zinc Oxyde	40 – 50 % 25 – 50 %   5 – 10%   5 – 10% about 2 % about 0.5 %   1 – 5 %   1 – 5 %

 

3M Adhesive Use

3M adhesive use in many application like in sticker paper, in post it paper, and like in envelope, also can use in plastic as glue when the cover is open. 3M adhesive also use in metal sign that can be stick when the cover is opened.

We can just buy this adhesive in adhesive shop normally in paper and stationary shop or in printing shop. Because of this adhesive is use volatile dilution usually use alcohol, this adhesive should be keep in closed can. For fast work use this adhesive can dilute in alcohol then sprayed in paper or other material, but the spray tool should be cleaned perfectly after use, because if dry this adhesive difficult to be cleaned. For cleaning usually dip in alcohol for several minutes and then rinse several time with alcohol too.

On application like on the envelope cover usually after gluing with this adhesive then covered with glassine paper, this paper is not stick with this glue and after dry can be loose but with good properties in the paper sticky and can directly stick to the envelope body.

Other kind adhesives:

• Thermoplastic Adhesive
• Nylon Adhesive

Curing of Cold Setting Phenolic Glues

In the curing of the cold setting phenolic adhesives is that they are capable of giving good strength on curing at low temperatures, down to zero centigrade in fact. The setting of many other synthetic adhesives -even if they cure at all at low temperatures- is protracted and may result in a poor end product.

In the curing of the cold setting phenolic glues, the addition of an aqueous solution of an acid such as sulfuric, hydrochloric or acetic, causes the resin to be precipitated from solution. The acid commonly used as hardeners are therefore sulphonic acids derived from aromatic hydrocarbons, such as benzene or toluene sulphonic acid. These, or similar acids of certain aromatic compounds are compatible with the resin chiefly owing to the solubility effect of the sulphonic acid group. Alternatively, however, a phenolic resin that has itself been unsulphonated resins, para-toluene sulphonic acid is most often used it is a strong acid, its normal solution having a pH of less than 0.5.

In a study of the effect of pH on cold setting resin prepared from formal 4-dehyde and monohydric phenols, it has been shown that a "barrier pH" exists, above which practically speaking, curing does not take place at room temperature. The barrier pH is roughly between 1 and 3 depending on the type of phenol; with ordinary phenol it is about pH 1.

While most acid set phenolic glues appear to give joints of good durability over long periods, both at high and low temperatures, there is evidence that a higher proportion fall below a specified minimum strength after a number of years than with resorcinol glues and that the acid hardeners used definitely attack the wood". A method of eliminating some of the danger of acid attracts on wood has been described. It evolves the addition of a "protective solution" to the acid catalyzed glue. This protective solution is designed to liberate an alkaline substance when the wood is subjected to an elevated temperature either during fabrication or in subsequent use. The composition of the solution is not stated.

Polyvinyl Acetate Adhesives

The vinyl group comprises the reactive part of a large number of compounds that produce thermoplastic polymers, most of which are extremely useful as adhesives. They include polyvinyl esters, ether and acetals, polyvinyl alcohol and polystyrene. Polyvinyl acetate itself often use in water treatment, even know in some countries already forbidden. In many application vinyl acetate can use for adhesive or as coating material like paint.

The most important polyvinyl ester adhesive is polyvinyl acetate (PVA). As an adhesive, it is used in solution, in aqueous dispersion, and by hot melt technique, in one form or another it is probably the most widely used thermoplastic adhesive.

Vinyl acetate is a flammable liquid made commercially from acetylene and acetic acid in the presence of a catalyst. As the molecular weight increases the polymer ranges from a soft to a hard solid, soluble mainly in polar organic solvents; adhesive solution are commonly made up in ketones, lower alcohols and esters. As the molecular weight reaches the order of 100,000 the polymer becomes soluble in toluene.

By the most important form in which the adhesive is used is the aqueous dispersion, made by the important industrial process known as emulsion polymerization, a process in which the liquid monomer is first emulsified in water and then polymerized by heating in the presence of a catalyst. Although loosely referred to as an emulsion, the product is not a liquid/liquid system, but mainly an aqueous dispersion of swollen solid particles. The advantage of an aqueous dispersion is not only that it uses water as the conveying medium, but also that a higher solids/viscosity ratio is possible than with a solution. Polyvinyl acetate solutions increase in viscosity as the molecular weight material is desirable because of its film strength, a solution that is fluid enough to permit easy application must necessarily be of low concentration. Emulsion polymerization overcomes this disadvantage because the molecular weight of the dispersed polymer has little effect on the viscosity can be easily produced. The particle size of the polymer should, however, cover as wide as a range as possible.

The well-known PVA emulsion glue, with a polymer content of about 50% is a versatile industrial adhesive. After application to an adherent water is eliminated from the emulsion through evaporation and absorption by absorbent adherent, and this result in the swollen particles coalescing to form a coherent adhesive film. For satisfactory coalescence and film formation, a certain amount of plasticiser must be incorporated, of which dibutyl phthalate and butyl carbitol acetate are an example. The plasticizer is largely responsible for the main shortcoming of polyvinyl acetate emulsion adhesives, the creep under stress which takes place especially at raised temperatures. Recognising the defect, some specifications include a creep test. If the testing of a glued joint the strength obtained is dependent on the rate of loading, especially if the glue has low resistance to creep.

Creep can be reduced by adding a urea formaldehyde to a PVA emulsion; such a product is dealt with. Certain copolymers of polyvinyl acetate such as an acrylate copolymer can be emulsified and their use generally result in a more versatile adhesive with lower creep. Many PVA emulsion glues are nowadays based on copolymers, at least in part. Creep can also be reduced by adding a vinyl methyl ether/maleic an hydride copolymer.

The thickening agents such as starches, starch-ethers, methyl cellulose or sodium carboxymethyl cellulose and also anti foaming compounds are frequently added to the emulsions. The incorporation of preservatives and other additives has been comprehensively dealt with. Polyvinyl alcohol is sometimes added; it is an effective stabiliser. Although room temperatures stability is normally good, an emulsion is likely to break if the temperature falls to the freezing point of the aqueous phase. The addition of 13-17% of high molecular weight ethylene oxide polymer (a water-soluble thermoplastic resin that has not found much use as an adhesive) enables a re-wettable (solvent activated) adhesive to be formulated, presumably a rather low molecular weight polyvinyl alcohol would do the same.

Certain polyvinyl acetate emulsion adhesive can be spray dried and marketed as dry powder that can be re-dispersed by simply mixing with water. Polyvinyl acetate is not only a good adhesive for a large number of porous or fibrous materials such as paper, wood and leather, but also far many nonporous materials especially transparent plastic films such as cellophane, cellulose esters, vinyl and polyethylene terephthalate. A rather different adhesive use is in making bonded fiber fabric.


An interesting application is the use of a PVA emulsion to increase the adhesion between old and new concrete. There are two ways in which this may be done, either by coating to old concrete before applying the new cement mix, or mixing a proportion of the PVA emulsion with the new mix.

Polyvinyl acetate emulsion are reasonably flexible; nevertheless, added flexibility for applications such as bookbinding can be obtained by incorporating compatible rubber latices.

These glues are non-toxic, clean and easy to use and rapidly assume a useful degree of strength especially with highly absorbent adherents. Their heat resistance is satisfactory up to 50^o – 60^oC. Gap filling is not usually good but the addition of thickening agents improves it. Tensile shear strength (at the normal rate of loading used in testing glued joints) has been shown with a variety of timbers to be comparable with urea and phenolic glues, while giving for reason that are not clear – consistently less wood failure.

Adhesive Contents

Content of March 2008 - Urea Formaldehyde

• Urea Formaldehyde Adhesive
• Adhesive Scope Discussion

Content of April 2008 - Melamine Adhesive

• Hot Setting Phenolic Glues
• Conversion of Resol to Thermoset Resin (Resite)
• Novolak Formation
• Phenol Formaldehyde Adhesive
• Hardening of Melamine Adhesive
• Stability of Melamine Formaldehyde Resin
• Melamine Formaldehyde Adhesive
• Addition of Polyvinyl Acetate
• Incorporation of the Hardener in the Resin
• Curing Agents for UF Adhesive
• Water Toleration of Urea Formaldehyde Adhesive
• Chemicals Composition

Content of May 2008 - Phenol Formaldehyde

• Resorcinol Formaldehyde Adhesive
• The properties of phenol formaldehyde
• Phenolic Adhesive from Vegetable Tannins
• Thickening Agents
• Fillers and Extenders
• Sulphonated Phenolic Resin Adhesives
• Curing of Cold Setting Phenolic Glues
• Cold Setting Phenolic Glues
• Phenolic Epoxy Adhesive for Metal
• Curing Temperature Phenolic Glue

Content of June 2008 - Oak Adhesive

• The Gluing of Oak
• Wood to Metal Adhesive
• The Application and Properties of Resorcinol Glue
• Addition Filler to Resorcinol Resins
• Curing at Elevated Temperature
• Correlation PH and Mole of Formaldehyde
• The Hardening of Resorcinol Adhesives.
• Resorcinol Phenol Formaldehyde Adhesive

Content of July 2008 - Epoxy Adhesive

• Curing Agents of Epoxy Resin
• Epoxy Resin Adhesives
• Bisphenol A Epoxy Adhesive
• General Procedure of Bisphenol A Reaction
• Curing of Bisphenol Epoxy Resin
• Other Bisphenol Curing Factors

Adhesive Contents of August 2008 - Polyamine Adhesives

• Other Factors Curing of Bisphenol A
• Aliphatic Polyamine
• Polyamines Hardeners
• Aromatic Polyamines Hardeners
  

Polyamines Hardeners

This polyamine hardener can use of alkylene series. The amount of the alkylene series of polyamines which needs to be added is usually between 6 and 12 % of the weight of the resin depending on its epoxies content. Diethylenetriamine and triethylenetetramine react vigorously exothermally, a shortcoming that limits the amount of adhesive it is advisable to mix at one time unless steps are taken to dissipate the heat. These amines are hygroscopic, a property that should be borne in mind when working in conditions of high relative humidity. They are also liable to cause skin irritation and dermatitis in some persons, an effect that may be lessened to some extent by using an N-hydroxyalkyl derivative of these polyamines, such as N,N-bis (hydroxyethyl) diethylenetriamine.




Aliphatic amines react to form adhesives that five good strength with a variety of adherents including most metals, glass, wood and mainly plastics. In spite of the fact that certain types are cold curing, all give a higher bond strength if hot cured or post cured, for example, at a temperature of 80oC - 100 oC. In some cases hot curing increases hot strength even more than room temperature strength, but in making comparisons it is important not to overlook the fact that subjecting the glued joint to heat in the course of the test may be equivalent to deliberate post-curing.

Example of the bond strength obtainable with two aliphatic polyamines is given in the table. The effect of curing temperature is well emphasized, even in the case of the highly reactive triethylenetetramine. But a factor that also affects adhesive strength is the exothermic temperature rises (if any) that has been reached before the glue is applied.

Included in the large number of other aliphatic amines that are suitable as hardeners are amino ethers such as butanediol bis(aminopropyl) ether. There is evidence that some of these ethers cure more completely at low temperatures than the alkylenepolyamines.

Particularly valuable amine curing agents which contain both primary and secondary amino groups and also amido groups are the polyamides known as the ‘Versamids’. These polyamides are made be reacting a dimerized drying oil acid and a polyamines, particularly dilinoleic acid and ethylenediamine, and they react with epoxy resins to form versatile adhesives. The most useful Versamid hardener is those that are liquids as distinct from resinous solids, especially Versamid 115. In cases where the resultant viscosity of the adhesive is too high, solvent mixtures of the lower alcohol and hydrocarbons may be used a diluents.

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.