Epoxy resins


Dispensing media

Epoxy resins

When things get hot and wild

Modern lightweight construction using materials such as glass and carbon fiber composites is one of the main users of epoxy resins for laminating the fiber layers. But epoxy resin is also used as an adhesive for joining individual components. In addition to industries that have to rely on lightweight construction due to its special properties, this robust all-rounder is also used in particular in classic car body construction. Not only as a structural adhesive, but also for corrosion protection of the car body.

In the field of electronics, epoxy resin is used as an electro casting resin wherever protection against media and high temperature resistance are required. In particular, applications in the engine or exhaust system area, such as sound or temperature sensors including the control electronics, benefit from the properties of epoxy resins. In addition to temperature and media resistance, epoxy resins, especially highly filled variants, are characterized by low flammability and ember formation. 

As part of the process determination in our Technology Center, we empirically determine the ideal range for the material you qualify.

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Applications and requirements

2C self-leveling casting resins and adhesives

Low-viscosity epoxy resins are usually commercially available as 2C systems. These must be precisely mixed and dispensed in the specified mixing ratio according to the manufacturer's instructions and technical data sheet. As polyaddition adhesives, epoxies, like polyurethanes, are very sensitive to variations in the mixture.

In most cases, the A component corresponds to the epoxy resin. The B-component contains the hardener, which is often based on amines or thiols. The viscosity of the B-component is often significantly lower than that of the A-component. 

After mixing resin and hardener, the reactive volume is subject to a time-limited processing time, since the chemical reaction of curing already starts from the first contact of resin and hardener and thus leads to a more or less rapid increase in viscosity. This time interval is referred to as the pot life.

One property of epoxy casting resins is the high exothermicity of the curing reaction, i.e. larger quantities of the reactive mixture can give off a considerable amount of heat during the crosslinking reaction. Especially in high-volume applications, this can lead to component damage. An appropriate potting strategy with sequential application can control this effect. We are happy to support you with process development in our laboratory.

With the material preparation system MPS (Material Preparation System), the material is permanently recirculated in the line system, tempered and prepared under vacuum without gas bubbles. Pressure sensor control at critical points of the preparation system guarantees seamless process control over every production cycle. In addition, the material preparation system can also be refilled during operation in order not to lose machine availability due to unnecessary downtimes during refilling.

Epoxy-based 1C pasty adhesives

With the exception of a few examples, epoxy resin-based pasty adhesive systems are 1C formulated, i.e. resin and hardener are present next to each other. So that the reaction does not already occur during shipping, storage and preparation, the hardener component is often finely distributed as solid particles in the resin or is chemically immobilized.

The processing time of these materials (pot life) is therefore often very long. If the component is heated after application using an oven, infrared lamp, thermode or microwave, the hardener component melts or the immobilization of the hardener is cancelled and the chemical reaction takes place at a very high temperature in the range of minutes until handling strength is reached. Since mixing of resin and hardener is not necessary, it is often possible to apply the 1C epoxy resin directly from the dispensing pump. 

Sedimentation of fillers, as with the low-viscosity systems, does not occur here. Processing can be carried out directly from the original cartridge or hobbock containers via cartridge preparation or container emptying PPS.

Modern hybrid materials based on epoxy or acrylate are a special case. These 1C formulations have a high reactivity at room temperature. They are often used in the sensitive electronics sector, where high curing temperatures cannot be tolerated. A typical application is the precise application of material quantities in the µl range. With the mini-dis line, bdtronic offers the appropriate micro-dispensing technology. This enables even the smallest quantities to be applied with repeat accuracy using the proven and robust eccentric screw technology. Temperature control of the entire material strand of the plant up to the dispensing system is required to avoid total curing in material-carrying lines. In addition, the material reserves must be stored at a low temperature.

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Benefit from our expertise and many years of experience. Develop the optimum process for your requirements together with us. We are specialists for different applications and processes.