Adhesives and Sealants

Here are some of the most frequently asked questions with their answers from Adhesives and Sealants.

In a polyurethane adhesive I am using a hydrophilic fumed silica like AEROSIL R 200 or Cab-O-Sil M5 to adjust the rheological behaviour. Is there a chance to replace a certain amount of fumed silica and to avoid the viscosity drift during storage time?

RHEOBYK-R 606 is increasing the hydrogen bondings between the fumed silica particles. This is giving a much stronger rheology effect which allows to reduce the overall amount of fumed silica. It also avoids the viscosity drift over time by a more complete wetting of the silica. The recommended dosage is 10% based on the amount of fumed silica. The RHEOBYK-R 606 should be added before the fumed silica.

I have a 2 component polyurethane adhesive, filled with a 5µm CaCO3 used for panel production. The amount of CaCO3 which I have to add to the systems is resulting in a too high viscosity which makes it very difficult to pump and handle during application.

We recommend to test 0,5 % of BYK-W 969 calculated on the amount of filler. This will significantly reduce the viscosity.

For fire protection reasons I need to increase the level of ATH in my structural epoxy adhesive. When I do so, the viscosity is by far too high and I can not handle the system anymore. Can I use any additive to prevent this?

BYK-9076 is a very strong wetting and dispersing additive. It significantly reduces the viscosity to be able to put more ATH into the system. It is recommended to add the BYK-9076 before adding ATH.

I am using coarse mineral particles like CaCO3 and Aluminium hydroxide in my epoxy adhesive. During storage the particles are settling and forming a hard sediment at the bottom. How can I avoid this by using one of your additives?

Our rheology additive RHEOBYK-430 is creating a pseudoplastic flow behaviour. The higher viscosity at low shear stress will prevent the settling of the particles.

We have a water based cold seal adhesive for food packaging like candy bars. We are searching for a silicone free defoamer with FDA §175.300 and PIM EC 10/2011.

First recommendation for this application is BYK-016. It is a polymer defoamer which complies with FDA §175.300 and PIM 10/2011 regulation without restrictions. Recommended dosage is 0.3 -0.5 %.

I am searching a defoamer for a UV curing acrylic adhesive. The defoamer should not have any negative impact on adhesion properties.

We have seen 0.3 % of BYK-1790 as a very efficient defoamer for UV curing acrylic adhesives. The defoamer BYK-1790 is based on polymers and has no negative impact on adhesion properties.

We are producing hot melts in an underwater pelletizing machine. The final product is forming hard blocks during transportation in the bags. We can use powders like talcum or stearate to prevent the blocking. We are searching for a dust free solution which is easy to handle to prevent the blocking of the pellets.

You can use HORDAMER PE 02 which is added into the cooling water system at a dosage of 1 to 4 % based on the amount of water in your system. HORDAMER PE 02 is a stable dispersion of a primary polyethylene in water. Even at low dosages it will remain stable and not separate and float on the water surface. On the pellets it creates a very thin layer of product to avoid the blocking. The product complies with FDA §175.300. In most of the water cooling systems the HORDAMER PE 02 will tend to stabilize foam. We recommend to add 0.05 to 0.2 % of a defoamer such as the polymer defoamer BYK-014 or the modified silicone defoamer BYK-022.

We are seeing substrate wetting difficulties like de-wetting and cratering when we apply our water based acrylic adhesive onto a polyester carrier film. What do you recommend to achieve a homogeneous adhesive film on that substate?

Main reasons for these difficulties are the differences in surface tension of your acrylic adhesive and the surface tension of the polyester film. Adding 0.3 % of BYK-349 will significantly reduce the surface tension of the adhesive to achieve a homogeneous wetting of the polyester film. BYK-349 is a modified silicone surfactant and according to our knowledge does not have a negative impact on adhesion properties. A silicone-free alternative would be 0.5 to 1 % of BYK-3410 to achieve a good substrate wetting. This product tends to stabilize foam. When you have already got a defoamer in your system, this is often enough. If not, we recommend to add 0.2% BYK-014.

What would your approach be to improve the adhesion of a water based adhesive between cardboard and laminated paper. Applications are gift boxes or paper shopping bags which do have an OPP or BOPP laminated film on top.

We have seen an improved adhesion in this application when adding HORDAMER PE 02 into the water based adhesive. HORDAMER PE 02 is more seen as a part of the binder and therefore dosages of 20 to 40 % are necessary. HORDAMER PE 02 is a very polar primary polyethylene dispersion in water.

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