Journey towards independence from fossil solvents
K.K. Sengupta ISSPA Mitra and Director, Centre for Fundamental Studies in Coatings Technology Kolkata
WE were just doing the same as other fellow Indians – Listening the lecture of our honorable Prime Minister from Red Fort on the eve of our 68th independence day.
There are messages for each of us, for all Indians irrespective of age, sex, education, religion and social status.
And, for us too, those of us, who are engaged in coating profession – about cleanliness, environment and import substitution.
Being one of the proud members of ISSPA, the largest paint association, can confidently declare that we can reduce import of petroleum crude.
If implemented, it will be a three in one result, which will take care about cleanliness; environment and import substitution at one go. How?
The whole coating world is aware about the disadvantage of using petroleum hydrocarbon and our helplessness during use, but there is a way by which we can remove our dependency on petroleum solvents part by part, finally to zero.
Paints can be divided broadly into two segments, viz. Industrial and decorative, the decorative consists of water borne and solvent borne. Approximately 40% of total decorative paint is solvent borne.
In an article “Surveying the Scene” by Mr. Ravi Marphatia in Paintindia, December 2012 issue1, we find some facts about the market for Paints and Coatings in 2011, where market share of decorative coatings is shown as 77.5% of total market volume of 2,205,000 tonnes. Therefore market share of decorative paints in 2011 was 1,710,000 tonnes, considering a humble double figure growth @ 15% of decorative paints market, today the figure for 2014 will be approximately around 2600000 tonnes, if we assume that 40% of which is solvent borne coatings then it comes to 1040000 tonnes, around 50% of which is a petroleum hydrocarbon solvent.
The primary function of solvent is mainly to keep the coating material in liquid form, during the process of drying, this solvent evaporates out from the wet film and goes into the environment.
Now we will carefully examine all possibilities to remove this shackle as to show the solidarity by the Indian Paint Industry to the expectations of our honorable Prime Minister.
Chemists, Technologists from the field of paint and coating industries were already in the process of finding the replacement of petroleum hydrocarbon solvent from decorative paints, as a result we find various coatings in the name of high solid material, solvent less material, powder coating and water borne coatings, but none of the above can claim a cent percent replacement for solvent borne decorative coating materials, so the petroleum hydrocarbon solvent borne decorative coatings run side by side of the new concepts.Though there is another technology has been evolved,which is incorporating of water into petroleum hydrocarbon solvent borne decorative coating materials. But this technology has neither any official standard on the functional ingredients or on the work procedure and the final specification.
We should not have jumped straight from solvent to water, by-passing another solvent, which is miscible with water and with many organic solvents, including acetic acid, acetone, benzene, carbon tetrachloride, chloroform, diethyl ether, ethylene glycol, glycerol, nitro-methane, pyridine, toluene and mineral turpentine oil etc.
This solvent can dissolve rosin, ester of rosin, shellac, poly vinyl butyl resin, ketone formaldehyde resin, fumaric adduct of rosin and polyamide resin.
The said solvent is ethanol. Ethanol, also called ethyl alcohol, pure alcohol, alcohol, spirit etc. it is a volatile, flammable, colorless liquid with the following characteristics - Formula – C2H6O,Odor – Characteristic alcohol odor detectable even at 80 - 100 ppm. CAS No – 64-17-5,IUPAC ID – Ethanol, Boiling Point – 78.37°C,Density – 789.00 kg/m³,Viscosity – 1.200 Cps. @ 20°C,Flash Point (Abel Closed Cup) – 16 °C (61 °F; 289 K), Vapor Pressure – 59.3 mm Hg @ 20°C, Vapor Density - 1.59 Auto IgnitionTemperature – 392°C, Molar mass – 46.06844 g/mol. Evaporation Rate – 100%, Chemical Stability – Stable, Hazardous Polymerisation – Will not occur.
Paint based on ethanol is not a new idea; road marking paint for asphalt roads and mould release paint for foundry are the example.
General purpose synthetic enamels in decorative segment can be made by ethanol and technology for ethanol soluble hard resins and alkyds are available. An Immediate change is very much essential, how long we will spend hard currency for a material just to allow it to pollute the environment.
This article is all about replacing mineral turpentine oil by ethanol that will only be possible, when ethanol will be available in large quantity and at an affordable price.
We have heard about “Cellulose”, which is a material of very high importance for modern world. Cellulose
is processed to produce papers and fibres and is chemically modified to yield substances used in the manufacture of such items as plastics, photographic films, and rayon. Other cellulose derivatives are used as adhesives, explosives, thickening agents for foods, and in moisture-proof coatings.
Cellulose is an insoluble substance which is the main constituent of plant cell walls and of vegetable fibres such as cotton. It is a polysaccharide consisting of chains of glucose monomers. Cellulose comprises about 33 percent of all vegetable matter (90 percent of cotton and 50 percent of wood are cellulose) and is the most abundant of all naturally occurring organic compounds.
Though humans lack the enzyme necessary to digest cellulose, but cellulose is a food for herbivorous animals (e.g., cows, horses and termites) because they retain it long enough for digestion by microorganisms present in the alimentary tract; protozoans in the gut of insects such as termites which also digest cellulose.
Ruminants - animals such as cattle, goats, sheep, bison, buffalo, deer, and antelope all digest cellulose, but even these animals do not themselves have an enzyme that digests this material. Instead, these animals harbor microbes that can digest cellulose. Ruminants still cannot eat wood or cotton.
Termites, on the other hand, can feed on various types of wood. Research in the late 1990s showed that certain types of termites had the ability to produce enough cellulase (an enzyme that converts cellulose into glucose or a disaccharide.) in the mid –gut to support their own survival. However, other species of termites do not have the capacity to produce enough cellulase independently and must depend on microbes from the domains Archaea (microorganisms which are similar to bacteria in size and simplicity of structure but radically different in molecular organization. They are now believed to constitute an ancient group which is intermediate between the bacteria and eukaryotes), Eubacteria (A bacterium found mainly in the intestines of vertebrates and Gram-positive, anaerobic, rod-shaped bacteria) to break down cellulose. Regardless of the various levels of termite independence, there exists a symbiotic relationship between termites and over 400 species of microorganisms, analogous to that of ruminants and their microbes. The termite gut is even designed to provide energy-yielding substrates for the microbes. Both protists and fungi are attributed to the production of supplementary enzymes.
People have long been interested in tapping into the energy in cellulose, aimed at converting cellulosic material into ethanol, Cellulose must first be hydrolyzed into smaller sugar components such as glucose, pentose or hexose before it can be fermented into bioethanol. One method uses acids to hydrolyze cellulose but this can destroy much of the sugar in the process. Another way to hydrolyze cellulose is by mimicking the microorganisms inside ruminants and termites.
Second generation or cellulosic ethanol is produced from agricultural residues containing cellulosic biomass* – such as the stalks, leaves, bagasse, husks of rice, wheat, wood chips, sawdust, municipal solid waste or energy crops.
These agricultural residues contain lignocellulosic fibers, which can be converted into fermentable sugars. Enzymes play a vital role in the conversion of lignocellulosic fibers and leading enzyme manufacturers have been successful in identifying the right enzymes for this conversion process. During the ethanol production process, lignin, a polymer can also be extracted from biomass. Though lignin can be used to produce power to meet the facility's energy needs but lignin can be consumed to produce high value raw materials.
The last decade has seen significant progress in innovation of enzymes for hydrolysis of various biomasses advancing from a pilot facility to demonstration facility and today a commercial facility.
The agricultural sector has long been the backbone of India's economy. It also presents a unique opportunity to develop second generation ethanol industry due to availability of vast agricultural residues. According to the Report millions of tons of biomass residues from rice straw and husks,wheat straw and husks, sugarcane leaves and bagasse, Banana plants and leaves, municipal solid waste (MSW) and other sources will be available annually in India for second generation ethanol conversion by 2020, without changing today's agricultural land-use patterns or cultivating new energy crops. According to this report, by 2020 the available biomass residue could in theory be converted into between 34 billion and 50 billion liters of second generation ethanol annually.
We import almost 80% of crude oil and depend on a few countries that produce them, but there is a need for focusing on immediate change, right now.
This industry has potential in generating jobs, enhance rural development, reduce emissions of carbon dioxide, this could create revenue to a staggering $ 20 billion annually.
Apart from the above activities, the primary requirement is to draw national standard on all the raw materials to be used to produce the alcohol based paints. Specification for the alcohol based primer and enamel may be drawn in line with IS: 2074 for primer and IS: 2932 for synthetic enamel paint by proper authority with assistance from Associations of Paints in India, Associations of Indian Resin Manufacturers, NABL Accredited Chemical Testing Laboratories in private and public sectors and institutions for paints and coatings.
Thus the change will be initiated from here, when the end users will get a product at an attractive price, which will have much less or zero effect on the environment, which will enforce reduction of imports and contribute cleanliness by turning wastes into national assets.
Plant material, vegetation, or agricultural waste used as a fuel or energy source.
- Surveying the Scene, by Shri Ravi Marphatia, Paintindia, December 2011. 2. Can second generation ethanol fuel India's growth? G S Krishnan, Business Standard, Mumbai, November 15, 2013. 3. Cellulose Digestion - Science Encyclopedia.
Fig. 14 illustrates the usage of polymer nanocomposites parts.
Fig 15: Timeline for commercialization of products by automotive players
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