What is a 'Green' Resin?


The Naked Truth Revealed
While no one
any longer questions that “green” is good, resin suppliers are facing and providing a variety of  “solutions” to the question of what actually constitutes green?

Resin formulations are more an evolution in materials engineering than some form of chemical wizardry. The same applies to the “greening” of resins.  NCS Resins and Reichhold continue to examine their recipes and find ways to become truly environmentally and user friendly without misleading our customers or sacrificing on their requirements. True “greening” can be described as follows...


Biodegradability:

Glass-fibre composites have been purposely designed to last as long as possible with the highest resistance to weathering and deterioration. It is made into products such as piping, yachts, chemical resistant tanks and sanitary-ware. In these applications the product is expected to last decades. Thus actual “biodegradability” of resin is unthinkable. There are very rarely requests from our customers for products that must deteriorate and degrade. NCS Resins have no biodegradable systems nor are we working on such systems though we know that other products degrade faster than our products do.

 

Resins made from recycled content:

NCS Resins produces a resin that is based on recycled Polyethylene Terephthalate (PET). This is a thermoplastic material used in the production of products such as plastic soft drink bottles.  PET can be used to replace some of the acid and glycol components that make up a polyester resin. This requires that the PET to be made into a pre-polymer which is then further reacted to produce a resin. Unsaturated polyester resins made from PET are usually tougher and have higher heat strength than conventional unsaturated polyester resins however the processes involved in sorting and preparing the recycled PET are costly and impacts the resin cost making it a little more expensive than standard resins.

Ask your sales rep for details on NCS 362 PA.

 

Recycled glass-fibre composites as a filler for polymer concrete:

Glass-fibre composites are made up from thermosetting materials and unlike thermoplastics cannot be melted or re-used in this manner. The hardening of the resin is irreversible and the hardened product is insoluble in most solvents making it difficult to reprocess.

NCS Resins are undergoing feasibility studies and are conducting tests on polymer concrete made from recycled fiberglass. The most cost effective method is by grinding the composite waste to a graded format. This can then be used in Polymer concrete, though currently it has not provided better strength than some systems using quartzite and calcium carbonate as a filler. It does however provide better bulking - sometimes up to 2.5 times better in volume than calcium carbonate with better cure rates. We believe there is merit for recycled glass-fibre composite in some applications providing that it is free of contaminants.

 

Resins made from renewable content:

Natural and modified natural oils have long been established as raw materials for polyester alkyd resins. They can be either reacted into the polymer or used as modifiers. Unsaturated polyester resins made with soybean oil have been around since the 1950s. It is however only recently that this raw material has been used to produce polyester resin systems equal in strength or better than conventional GP resins. Unfortunately organic sourced renewable raw materials cost considerably more to produce due to logistical constraints and the extra processing required in making it usable. Reichhold have found that resin users are reluctant to pay a premium for such resins and thus it is used in limited applications. The renewable content only makes up 30-60% of the resin itself. Some resin suppliers and manufacturers have created a misleading impression that it is a “100% green” resin when, in our opinion, it is not.

Another problem prohibiting the commercialization of renewable content resin is the competition with agricultural land and feed-stocks used for food production and legislation against this in some countries.

 

Low styrene emission and low styrene content resins:

There is often confusion between low styrene content (LS) and low styrene emission resins (LSE). Low styrene emission resins employ the use of styrene suppressants that trap most of the styrene vapours beneath the surface of an open moulded composite laminate. The composite usually cures to a waxy surface and the amount of styrene vapours released into the atmosphere is greatly reduced.

To establish and evaluate exactly just how much styrene gets emitted and to compare styrene emissions is easy to quantify by anyone with an accurate 2 decimal balance. All that is required is that one pours an amount of catalysed resin into a shallow dish with a large surface area - like a bucket lid. Weigh the container on the scale as soon as the catalysed resin is poured and then again once the resin has achieved its full barcol. The difference is the amount of styrene emitted. We would encourage concerned consumers to evaluate L.S.E resins disguised behind marketing hype of “green” by doing their own tests. This way you educate yourself on real facts as opposed to marketing gimmicks and hype.

Low styrene content resins are those resins that contain less than 35% of styrene but still maintain the viscosity of standard resins. This may be achieved by substituting the styrene for other less volatile monomers like acrylates and or modifying the resin to require less monomer. Low styrene content resins are generally expensive since styrene monomer is the most cost effective monomer available for unsaturated polyester resins and reducing the styrene content in favour of the more expensive low volatile monomers adversely influences the overall resin cost.


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