MANUFACTURE
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Mastering mixing processes for industrial scale-up
Nesrin Hesso, Stéphanie Roux - VMI Mixing
Developing a new skin care or beauty product must be achieved over increasingly shorter times, for ever more frequent market launches in response to consumer demand for ever more diversified, personalised and effective products. The laboratory phase is critical to develop your formulation and set the associated process. However, you must anticipate the industrial manufacturing requirements of your new product ahead to integrate process parameters that will be crucial for the quality of your upcoming product. Your choices in the laboratory will determine the success or failure of your formulation when scaled up.
Key stages of a product launch The launch of a new product in the care and cosmetics industry is usually associated with the following five key steps. ■ The identification of ingredients and raw materials. ■ Formulation development in the laboratory. ■ Evaluation: series of tests (in vitro, ex vivo, tolerance, clinical trials, consumer tests etc.) ■ The regulation: validate the conformity of the product and proceed to its registration. Depending on the country where the product is marketed, this stage can considerably extend the project’s duration. ■ Distribution channel: importers, distributors, retailers, online sales etc. However, a crucial sixth step should not be
neglected: the process phase. This phase takes place between formulation and evaluation. It includes determining of the elements that will allow the manufacturing of the product: equipment, the geometry of the mixing tools, process parameters (speed, time, temperature, vacuum), sterilization and cleaning data or extrapolation. The process is an essential variable during
the development of a new product because several economic and safety issues depend on it. These include the following: ■ The finished product’s quality, to obtain the same result in the industrial production phase. ■ Safety for the operators in production and for the final consumer. ■ The marketing of the product. ■ Production yields: manufacturing time, energy, water, and detergent consumption.
The main principles and challenges of the mixing process Mixing is a unitary operation present in the
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transformation processes. It consists of bringing together several components to produce a homogeneous result. The procedure makes it possible to get the ingredients into contact and promote the transfer of heat, matter, quantity, and movement according to the application. The operation provides mechanical
energy, which increases the homogeneity and decreases the segregation of the mixture. Depending on the manufacturer’s homogeneity requirements, a successful mixture can be analysed according to the following. ■ The uniform concentration of the mixture from any sample. ■ The specific segregation scale: homogeneous mixture at the macromolecular, nano-molecular, micro-molecular scale. ■ An optimal mixing time to calculate the required manufacturing time.
The mechanical stirring system A wide variety of mixing technologies exist. One of the most widespread is the mechanical stirring system (agitated tank). Consider the below five key parameters that impact the mixture. ■ The tank (vessel): the dimensions and shape of the bottom of the tank. ■ Type and number of agitators. ■ The rotation of the mobile: speed, flow regime (laminar or turbulent). ■ Duration of mixing. ■ The physical conditions imposed (pressure, vacuum, temperature).
Five steps to follow for a successful mixing To obtain a good agitation, laboratories or industries must take different parameters into account: ■ The nature of the product (liquid, powder, solubility) and its fluids’ rheology (viscosity). ■ The technical dimension: stirring tool, peripheral speed, shear rate etc. ■ The economic dimension: sector of activity, geographical location, consumption levels (energy, water, production time etc.).
1: Identify the type of mixture to be made The first step is to know the mixture’s nature to be made: is it a liquid/liquid, liquid/ powder mixture? Are the liquids miscible or immiscible?
2: Characterisation of the ingredients mixed After identifying the type of mixture to be made, it is necessary to know the characteristics and rheology of the ingredients used: density, solubility, granulometry, density, viscosity, crystals, capsule, gas etc.
3: Characterisation of the mixing tool Good knowledge of the type of mixture and the ingredients involved makes it possible to determine the flow required for optimal mixing: radial, axial, rapid agitation, etc. The design and geometry of the tool vary the shear and flow levels.
June 2022 PERSONAL CARE
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