Attributes/Applications: UHU plus endfest is a two component, epoxy resin based glue that has a long curing time and enables the user to make extremely strong bonds between numerous combinations of materials. UHU plus bonds are resistant to moisture, oil, thinned acids and lyes as well as many solvents. This adhesive is especially good for gluing metal, rubber, wood and plastic (primarily duroplastics) - for example, phenolic, melamine and polyester resins. It also works well, however, with mineral composites like ceramics and cement. It has proven, for example, to be very good for attaching NEODYMIUM MAGNETS for closure purposes on doors, boxes or portfolios where extremely strong bonds must be attained by relatively small areas of glue.
When cured, the glue has a transparent-yellowish colour and takes well to sanding. It attains its full adhesive strength after about twelve hours and is then very weather and aging resistant.
Treatment: As is generally the case in gluing work, the pieces to be glued must be lightly sanded and thoroughly cleaned and de-greased. In order to mix small amounts of the glue, we recommend the use of a glass plate or something similar and a wooden or metal spatula. The two components must be stirred together for as long as it takes to attain a homogenous colour. The glue can be applied to one side or, for rough surfaces, two sides with a spatula or a bristle brush; in the case of larger surface areas, you can use a palette knife or a similar tool.
By varying the amounts of the hardener, it is possible to modify the attributes the cured epoxy will have: :
- 100:50 parts by weight (resin to hardener) produce a harder glue that is somewhat more resistant to heat, water and chemicals.
- 100:80 parts by weight (resin to hardener) is the standard mixing ratio for universal application – this corresponds to two equal lengths of material from each tube and thereby a 100:100 ratio by volume).
- 100:120 (resin to hardener) produces a final adhesion with good flexibility and improved adhesive attributes (peel resistance) but, it should be noted, less heat and chemical resistance.
Small variations in the resin/hardener ratio produce no noticeable differences. Especially high strength and stability can be achieved when the curing is done under high temperatures between 70 and 180 degrees centigrade. The high temperatures also reduce the curing times: approx. 45 minutes at 70 °C, about 5 minutes at 150 to 180 °C.
Applications: Highly stress-able, gap-bridging bonds require the use of two component glues which, after both components have been mixed together, will cure into a solid plastic. The two component glues which are based on epoxy resin are distinguished by their being especially good for use with metals.
Treatment: Resin and curing agent (hardener) – the names of the two components – must be mixed in the correct ratios so as to ensure that the full adhesive strength is attained. The apportioning can be done by eye in the case of small amounts but larger amounts (over 20 grams) should be done by weight. The limited working life (open time) requires that the adhesive mixture be made in a sufficient amount to complete the job at hand. During the curing process the glue gives off a great deal of heat – temperatures over 100 ºC can be reached and these can lead to deformations in thin plastic assembly pieces.
Important: Larger amounts of two component glues start to turn into gels sooner because the heat being produced accelerates the reaction. This can be redressed by doing the mixing in a flat bowl. The opposite is naturally also true: by heating the mixture with, for example, a hair dryer, the hardening time of two component glue is shortened. Care should be taken when reclosing the containers: the caps should not be interchanged because they will then glue shut.