Aerosol hairspray cans are a cosmetic product used by 86% of women in the United States.(3) The consumer demand for hair products has stayed relatively steady since the invention of hairspray. Industrial suppliers can increase their net profit of aerosol hairspray production by analyzing and possibly optimizing their manufacturing process, mores specifically, the production of the most widely used aerosol propellant, dimethyl ether (DME). The optimization of a thermally coupled DME reactor (OTCDR) proves to be economical, energy sufficient, and increase the net profit of the industrial plant. It is in the best interest of industrial aerosol hairspray manufacturers to consider multiple alternative production processes and, or optimization of current processes.
Aerosol cans were first patented in the United States in 1941. This innovation did not have much impact on the world until World War ΙΙ. The U.S. military introduced the aerosol cans for dispensing insecticide. The potential uses of aerosol cans were quickly recognized. The first commercial hairsprays marketed in the late 1940s. Hairsprays belong to a class of personal care products that help hair hold a desired style. Hairsprays are formulated as aerosols that are powdered pressurized gasses. The design of hairspray efficiency, consumer appeal
Aerosol cans serve as convenient packages for paints, medications, insecticides, adhesives, food, and cosmetics. The structure of an aerosol is shown below in Figure 1. Most aerosol cans are made of aluminum and are mono-bloc in construction. The bottom of the can has a curved bottom to resist the pressure of the gas and for greater ease of full product use.
Figure 1. On the left is the inside of a compressed aerosol can. On the right is a close up view of the valve.
The contents of aerosol are made up of two components, the product and the propellant. The propellant can exist as a liquefied gas or as a compressed gas as shown in Figure 1. A propellant that exists as a gas occupies the headspace above the liquid in the can and when the aerosol valves is opened the pressure pushes the liquid out of the can. The propellant boils below room temperature and the product boils at a temperature much higher than room temperature. The product is the substance of use. The consistency of the expelled product depends on the chemical makeup of the propellant and product, the ratio of propellant to product, the pressure of the propellant, and the size and shape of the valve system.
The raw materials of hairspray include holding agents, solvents, additives, propellants, and packaging. Holding agents are polymers, also called resins, poses the ability to form films upon drying. Liquid drops run down the hair shaft until the intersection of another hair where an invisible bond forms. A popular, relatively inexpensive holding agent is polyvinylpyrrolidone (PVP), this particular resin is quite sticky. The copolymer PVPVA is formed when vinyl acetate is added to PVP. Solvents make up the largest weight percent of the aerosol hairspray (80 % by weight). Water is the most popular solvent. When water is used the drying time is longer and there is increased change of corrosion. Ethanol used to be a commonly used solvent alternative until it was termed a volatile organic compound (VOC). There is still currently no acceptable replacement. Additives in hairspray mainly consist of plasticizers, and neutralizing, anit-corrosion agents. Some of the popular additives include isopropyl myristate, diethylphtalate, silicones, and aminomethyl propanol (AMP).
Aerosol hairspray propellants serve as the raw material of most interest throughout this text. The Hairspray propellants originally used were chlorofluorocarbon gasses (CFCs), in the late 1970’s they were banned because of their contribution to the depletion of the upper atmosphere ozone layer. Hydrocarbon propellants like...