Chapter 7 Formulation_2014

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ICE402 Product Technology Formulation

Budi H. Bisowarno

Jurusan Teknik Kimia

Universitas Katolik Parahyangan

Bandung, April 2014

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Final Specifications:

Product: chemical vs device?

Chemical products: homogeneous vs heterogeneous?

Devices chemical technology?

Final specification of the products?

From product to process operation?

Chemical manufacturing is the process through which a chemical is synthesized from raw materials or other chemical feedstocks. Product formulation is the process by which chemical products, composed of one or more ingredients, are prepared according to the product formula.

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Final Specification (cussler) 1. Product Structure 2. Product Attributes 3. Chemical Triggers

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1. Chemical composition. What is the planned product made of? If it is chemically pure, what is its chemical structure? If it is a device, how much can its composition be changed without affecting its performance?

2. Physical geometry. What product characteristics are fixed? Are there fixed macroscopic dimensions? Is there any unusual physics?

3. Chemical reactions. Does the product change chemically during use? Do acid, bases, and salt affect these changes?

4. Product thermodynamics. what is the product's phase? Is this phase thermodynamically stable or metastable?

PRODUCT STRUCTURE (cussler)

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1. Structural attributes. These include the product's physical properties such as its strength and elasticity. These attributes are more important for devices than for chemical products

2. Equilibrium changes. Many chemical products will show major changes in equilibrium as a consequence of altered temperature, pH, or some other process variable.

3. Key rate processes. The most obvious is the rate of any important chemical reaction. Less obvious but often important are rates of heat transfer, fluid flow or diffusion, which are often manipulated by changes in interfacial area.

PRODUCT ATTRIBUTES

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CHEMICAL TRIGGERS

1. Solvents. These dissolve or disperse the product so it becomes useful.

2. Temperature changes. The most common example is regenerating a product - such as an adsorbent - by heating or cooling.

3. Chemical reactions. The most common occur because of pH changes or hydrolysis

4. Other physical changes. These may include pressured, detergency, and electric field.

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Micro structured products

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Device Manufacture

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Problem 5.2. Hot Sake

By pushing the bottom of the can the water in the container is brought into the bed of calcium oxide and it triggers exothermic reaction. When you turn the can over, heat convection will enhance the heat transfer within sake. From the information given, estimate the amount of calcium oxide and water required

Formulation

Formula = recipe

Is a scientific disciple?

Formulation is most closely guarded with trade secret on account of their often considerable economic value.

A large proportion of chemical substances, whether inorganic or organic, natural or synthetic, must be refined and formulated before they can be used in medicine, industry, agriculture, foods, cosmetics, and so on.

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Formulation

Your first real product will usually be made in the laboratory to develop the recipe for full scale production. Experimenting in the lab takes much less time and is much cheaper than on a full scale.

The laboratory techniques used in product development are no different from those used in chemical research and education.

In research and education, you can choose freely which variables you want to investigate.

In product development you must try to get a feeling for the effect of all important variables.

However, you must be clever if you want to investigate everything with limited means and a limited amount of time.

Wesselingh, Kill, and Vigild, 2007, Design and Development of Biological, Chemical, Food and Pharmaceutical Products, John Wiley and Sons.

Powder Coatings

The big advantage of powder coatings over paints is that they use no solvents; coating material that is not used, can be recycled. In addition, powder coatings allow a fairly thick layer to be applied in one go.

This yields a low price and is better for the environment.

A big problem in the development of powder coatings was the conflicting requirements for flow (melting) and reaction.

To solve these required a good concept and a large experimental program.

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Knowledge of

chemicals,

synthetic chemical reactions,

reaction conditions,

catalysts

are needed to complete product formulation

Main Components

Three main components for the final polymer layer

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The first step in the polymerization

NPG + TPA a polyester + H2O Note: - Liquid phase - Excess NPG - Amount of reactant

ratio

The second step in the polymerization

IPA is added to cause the polymers to become acid-capped. The melt is then cooled and milled to a powder. Thermoplastic films from linear polyesters do not have good mechanical and chemical properties

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Particles before application

The cross-linker used is tri-glycidyl-iso-cyanurate or TGIC. It is a solid at room temperature, and made in the form of a powder.

TGIC and polyester powders are mixed intimately in an extruder at about 120C. At this point other components such as pigments can be added. The extruder is operated below the melting temperature of all components.

The cross-linking reaction

As a result, the particles of polyester and TGIC stick together, but do not mix on a molecular scale. This is essential to avoid cross-linking before the powder is applied.

The cross-linking reaction only starts above the melting temperature of the powder, but then it is rapid. It takes only 100 s at 220C to spread out and form a closed flat layer of polymer.

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Your Job

You have to find conditions for getting a good film in the full scale production recipe.

Before beginning your experimental program seriously, it is usually a good idea to spend a bit of time on orienting yourself by experiment.

As an engineer, you have been taught to work systematically. So you may be tempted to investigate your design space systematically by doing experiments that cover the whole range of variables.

However, this is not a good idea!

Systematic Experiment?

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How to Limit Experimental Work

understand how the product is to work

to use models of the process or parts of it to find suitable starting values

to do many experiments simultaneously.

Setting up an experimental program is usually iterative you learn to understand your problem while working on it.

understand how the product is to work

The powder is sprayed on the cold substrate; it adheres because it has been charged electrically. The substrate with adhering powder goes into a curing oven, where it is heated above the softening temperature of the polyester.

1. polyester flows and spreads over the substrate, and 2. TGIC diffuses into the polymer and starts cross-linking.

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understand how the product is to work

You can greatly reduce the number of variables to test by one simple observation.

understand how the product is to work

The first two are important; for the last one it is only important that the polyester is fine enough to allow a good distribution of the cross-linker throughout the particle. You take its diameter equal to that of the cross-linker sub-particle. To get an idea of the optimal particle size, the spraying operation should be analysed.

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understand how the product is to work

The liquid is pulled over the surface by a line tension . This depends on the interfacial tensions of liquid, solid and gas; it is lower than the surface tension. This tension is counteracted by forces due to the viscosity . The flattening will also depend on the initial size R0 of the drop. Finally you would expect the drop to become flatter with increasing time t .

understand how the product is to work

Flattening stops when the polymer gets cross-linked. This will not happen before TGIC has diffused into the polymer.

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Final Parameters

The particle size of the cross-linker seems to be important: it should be a few micrometres. The curing temperature has to be above the melting temperature of the polymer. Perhaps you can omit the curing time (11) in the program by taking it to be a multiple of the cross-linking time.

There are now two variables left.

a good search method

You may be varying more than two variables, and recording more than one result. However, the principle remains the same: you are trying to find a combination of variables that gives a good combination of properties. The method assume a single optimum in the desired set of properties. You run a risk of ending on a local optimum.

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Simultaneous Experiments

It can help to do different experiments simultaneously. A final remark: the real development of the powder coating process was not as straightforward as in our story. It was the result of many smaller projects, with many dead ends. Even so, it did not take 700 000 years!

Summary

In this lesson we have looked at some of the aspects of developing a recipe in the laboratory. The techniques used there are the same as in research and education. The key to this is to try to get an understanding of the process and its variables. Search good conditions using experimental results as a guide. The experiments can often be speeded up by doing tests in parallel.

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FLowsheet

Start with the recipe; with this in hand, construct a process diagram showing the steps in the process, and how they are connected. At this point do not worry about equipment that comes later. Then consider the ingredients and where they are added to the process. It is often instructive to look also at the amounts of required energy. And to look at the waste produced.

the lab recipe is no good on a large scale