The recent ban on plastic bags in Kenya has had a fair share of advantages and disadvantages in some segments of the manufacturing industry.
While multi national business enterprises dealing in the manufacture of polythene materials were grounded by the ban, the manufacturers of glue have had a field day. Same case applies to the dealers in paper industry.
In maintaining what remotely resembles an eco balance in packaging industry, the manufacturers and traders of canvas bags, baskets, tote bags etc stepped in to fill the gap, albeit in a record mischievous way: The Kenyan Supermarkets, which dished out 100 million polythene bags to shoppers every year (for free) are now selling their equivalents at Ksh 15-20 per piece. The shoppers lose, the manufacturers gain. It is a clear case of imbalance of trade.
Since the ban, we have received countless calls by Kenyan entrepreneurs asking whether we teach how to make the tote bags. Curiously, majority of the callers are businessmen from the more entrepreneurial Somali community.
But with complexities involved in the setup of the canvas and tote bag industry, quick thinking entrepreneurs have taken an alternative route to cash in on the opportunity of the moment.
Traders are now making paper bags to substitute the more expensive canvas and tote bags. This has subsequently come with heavy demand for glue.
Glues are emulsions, made by mixing collagen or amorphous polymers into appropriate solvents.
Proper understanding of the dynamics involved in making glue and adhesives is important for a manufacturer. For example, some thermoplastics do not cross-link, thus becoming insoluble, and it can be dissolved in many solvents other than water. One slow-drying formulation combines 5 to 15 percent of PVAC with ethyl alcohol (ethanol). The hardest of the polyvinyl esters, PVAC, offers good adhesion to most surfaces. A fast-drying counterpart combines the same amount with water! While mixing the ingredients, an appropriate level of agitation is crucial to ensuring the emulsion mixes adequately. Otherwise, the glue may settle once bottled, rendering it ineffective.
A technician at Express Marine Engineering PLC says that one type of glue mixing is low shear mixing which utilizes a low-speed propeller or turbine to slowly fold the polymer into the solvent. This process is time-consuming, with a vat of glue taking 12-24 hours to mix in some cases.
A more efficient option is a high shear disperser, which typically utilizes a high shear dispersion blade. He adds. “It works essentially like a large kitchen blender, drawing material up from beneath the mixing head and thrusting it through the blades in order to thoroughly break apart polymer particles and mix the emulsion” .
In large scale commercial production of glue, the primary processes may require an even more high-speed option, like a high-pressure homogenizer or colloid mill. These utilize a combination of shearing, agitation, and high pressure to emulsify adhesives.
Now the above technical language should not scare away a potential small scale manufacturer. Glue making is all about mixing at least four main components in their proportionate weights expressed as percentages, right temperature and voila! You have a glue. 😀
Post By Herman, Technical director, Cosmetics and Detergents Kenya Limited in association with Betty T. MD, Betty Industrial Chemicals Ltd. Other contributors are Lawrence Kongo, Regina Wanja, Emma Owiti James Marwa and Patrick Kubai.