PROTECTIVE COATINGS for Fuel & Chemical StoargesNovolac Epoxy vs Bisphenol F Epoxy Coating Systems
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Solutions for Fuel tanks, Petrol Stations, Chemical Storages & Chemical Industries.
We offer tank protective coating solutions to be used in various applications and circumstances.
We import raw materials to Australia, manufacture various resinous coating systems, supply the right material for your job, install the coating and maintain your asset for many years to come.
Our comprehensive after sale services includes discounted maintenance over the coming years. We understand the requirements of chemical industry and will help you minimise your overall cost on installation, maintenance and over hall as much as possible.
We can also help you with final protective coatings inspections and issuing all the required certificates. We serve a comprehensive cross-section of commercial & industrial sectors in Australia and Pacific region.
Why is the Novolac epoxy more proper solution than the Bisphenol F for chemical and fuel storages?
To respond to this question we should have an idea about Novolac chemical structure. Novolac resins are modifications of bisphenol F resins formed using excess phenol.
Bisphenol F is the simplest form of Novolac resin, but should not be confused with its related higher functionality analogues. Its functionality and performance properties are quite different from true Novolac.
Bisphenol F epoxy resin performance in wastewater treatment facilities is between bisphenol A epoxy resin and a true Novolac. For the purpose of this passage, bisphenol F epoxy resin will be considered its own class.
It is critical for decision makers to be able to distinguish between bisphenol F and other Novolac epoxy resins. In fact, some contractors, even some manufacturers cannot distinguish between the two. It results in using a low performing product and/or over-paying on purchasing a more durable system than the requirements of the project’s exposure environment.
The viscosity of Novolac resins is significantly higher than that of bisphenol F resins. Equally important, the functionality is also considerably greater. The higher viscosity and greater functionality of the Novolac resins make their heat and chemical resistance properties superior to those of bisphenol F.
Novolac resins provide two important performance advantages over bisphenol F resins:
First, Novolac resins possess greater chemical resistance properties because their very high functionality results in a very tight crosslink density.
Second, the larger number of aromatic ring structures increases heat resistance in the final system.
These properties tend to make a pure Novolac resin system more brittle than bisphenol A or bisphenol F resin systems, but this brittleness issue is generally addressed by formulation techniques and/or altering hardener selection.
While Novolac epoxy resins are exceptional in their properties, the material cost is much higher compared to the bisphenol-based resins. Hence, they are usually only used in crucial & critical conditions, where the substrate must be protected from highly acidic or corrosive chemicals.
Alka 111 and Alka 113 are two high chemical resistant products based on Novolac and Bisphenol F.
We offer formulating and technical advise on our range of products to increase performance and resistance against each project’s offensive chemicals. For this reason, we need the specifications of your project such as a detailed chemical composition of used materials and eaxtc temperature to be able to offer our best solution.
Role of epoxy curing agents in chemical and thermal resistance properties?
There are many curing agents that can be used for epoxy applications; of which polyamides and amidoamines, aliphatic amines and their modifications , cycloaliphatic amines and aromatic amines are often employed. However, the performance of epoxy curing systems is affected primarily by molecular weight of the epoxy resin as well as concentration of the curing agent.
Amidoamines and Polyamides are known for their water and corrosion resistance. They are most commonly used in metal coatings applications, particularly primers and mid-coats.
They have very excellent adhesion properties to concrete and well performance under humid conditions , commonly used in civil engineering applications such as flooring, concrete bonding and crack injection. They also find use in high solids coatings, adhesives, electrical encapsulation and wet lay-up laminating.
Cycloaliphatic amines are a type of curing agent that possesses good film hardness and good gloss. They also have good chemical resistance and mechanical properties, both at heat curing and high temperatures. Cycloaliphatic provide the most light-stable systems of all amine structures. This structure also provides greater heat resistance than linear aliphatic amines, increases rigidity, which improves mechanical strength over both aliphatic and fatty acid-based amines. They are slower reacting than aliphatic amines but faster than polyamides. Chemical resistance (non-solvent) is superior to aliphatic amines and polyamides. Bear in mind that they shouldn’t be used as a coating in fuel and solvent storage tanks.
Aliphatic amines were the first amine hardeners used in epoxy coatings. They are simple commodity chemicals that were available to react with epoxies. These include materials such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and several others.
The benefits of using these amines include high reactivity (fast cure) at ambient temperature and excellent solvent resistance because of their high functionality. Disadvantages such as limited flexibility and inefficient chemical reaction with the epoxy resin, which leads to surface carbonation or blushing.
For years, the most widely used aromatic amine was methylene dianiline (MDA). It offered a long pot life, the best acid and heat resistance, and excellent mechanical properties. It was also non-corrosive and non-irritating, moisture insensitive, and flexible. Colour stability was its major drawback. Unfortunately, it has been found to be systemically toxic. In addition, restrictions imposed by the U.S. Occupational Safety and Health Administration (OSHA) and health concerns in handling MDA have forced most formulators to stop using MDA. Fortunately, formulators have found alternative chemistries to satisfy most of the demands for performance properties of MDA.
In the bottom line , there are a number of parameters that should be considered before advising and determining the adequate coating solution for your project. These parameters are included in the type , name and concentration of chemical , temperature , humidity and moisture , type of substrate , gas or liquid pressure, food contact and light exposure . note that you should consult with the technical team to get the optimum solution.
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