Broadway’s Innovative Endothermic Blowing for Moulding Processes

Key Highlights:

• Broadway’s MasterFoam is a chemical foaming agent which instigates a reaction and creates a foaming effect whilst the material is in a liquefied state during the moulding process. 
• Endothermic blowing agents absorb energy during the reaction process, so the reaction is easy to control.
• From Broadway's trials, the company's blowing agents have proven to offer a multitude of benefits in both injection and extrusion moulding processes, at low addition rates.

Broadway is an ISO certified, UK manufacturer of colour and additive masterbatches and compounds. Their new blowing agent masterbatch was extensively trialled throughout 2023. The material – developed by Broadway’s in house technical team, is now marketed as MasterFoam. Moulders already using the additive have achieved notable reductions in polymer usage, cycle times and costs, as well as light-weighting their components. 

How does it work? 

Broadway’s MasterFoam is a chemical foaming agent (also known as a blowing agent). MasterFoam instigates a reaction which creates a foaming effect whilst the material is in a liquefied state during the moulding process. The foam expands as the thermoplastic cools in the mould. This process offsets the tendency for the moulded part to shrink whilst cooling, thus reducing sink marks.  

As the material hardens, a fine, regular foam structure forms within it, reducing its density. This means less polymer is needed to fill the mould cavity, therefore less material is required to complete the production run, reducing material costs by almost 10% in many instances. As a result, the moulded component is lighter, which of course offers obvious advantages in a variety of applications. 

MasterFoam is an endothermic blowing agent. Endothermic blowing agents absorb energy during the reaction process, so the reaction is easy to control. They typically only release carbon dioxide and water upon decomposition. Broadway states that this is a much safer product than widely available exothermic blowing agents. 

What are the benefits? 

MasterFoam offers many benefits. The application, polymer type and moulding conditions will determine which are achievable, and to what extent in each moulding. 

Following successful trials, an industry partner of Broadway suggest they could save 105 tonnes of polymer over a five year period in just two small packaging components, moulded for a leading multinational consumer goods company. They state this would result in a saving of £110,000 on material costs alone. For packaging components subject to the UK Plastic Packaging Tax (the rate of which is due to rise again in April), MasterFoam offers a further cost benefit due to the reduction in the volumes of polymer processed. 

Viscosity of the MasterFoam melt is lower than polymer on its own. This is due to bubbles beginning to form in the melt allowing for deformation. This lower viscosity results in a smoother, quicker injection stage. Shot speed is increased as the polymer must be ‘short shot’ into the mould (i.e. less polymer added), to allow a uniform expansion of the foam in the mould. Cooling times typically are reduced, all of which contributes towards a reduced cycle time and reduced energy demand and costs. 

In extrusion moulding trials, the use of Broadway’s extrusion grade additive (MasterFoam-Ex) doubled the running speed of a customer’s extrusion. This effectively doubled the capacity of their operation, without any capital investment in upgraded infrastructure. The reduced component weight was also highly beneficial for their application. Broadway suggests that the potential for this customer is huge.  

Another advantage is that the open cell structure offers improved acoustic and thermal insulation properties. This would be particularly beneficial in applications such as window frame profiles. Components used in construction are increasingly scrutinised for thermal efficiency.  

Trial results 

Over the past year, Broadway carried out a series of trials with different moulders. These covered various end applications in injection moulding trials using MasterFoam and MasterFoam – Ex. See the table below showing a summary of results from some of the trials carried out in 2023. 

As you can see from the table of results, Broadway’s blowing agents have proven to offer a multitude of benefits in both injection and extrusion moulding processes, at low addition rates. Supplied in masterbatch form, the cost of the additive is less than the value of the polymer saving it provides, so it has a real commercial appeal. In effect, the more a customer uses, the more they’ll be saving. And this is before any additional savings in energy, production efficiency, transportation and tax are considered. 

Why should I use Broadway’s blowing agents? 

Broadway’s injection grade chemical foaming agent – MasterFoam, is not an imported or traded masterbatch. It was developed in-house by Broadway’s technical team. It’s a made to order material, manufactured in the UK, offering fast turnarounds and security of supply. In 2023, MasterFoam produced the best results in independent trials, against a number of competitor blowing agents. Broadway has vast experience in the manufacture of colour and additive masterbatches and compounds. Their technical and sales support is also provided from their 90,000ft2 facility in Suffolk.  

Dr. Stephen Rayner, technical manager at Broadway, said: “Broadway’s MasterFoam allows our customers to achieve ‘more for less.’ This product provides a significant weight saving in the final moulded component, meaning less polymer is required. We’ve been delighted with the results we’ve seen from customer trials over the past year.  

"We’re continuing our sustained effort to expand our product portfolio with new offerings which support customers in achieving their commercial and sustainability goals.”