Aerosol spray is a type of dispensing system which creates an aerosol mist of liquid particles. It comprises a can or bottle that contains a payload, and a propellant under pressure. When the container's valve is opened, the payload is forced out of a small opening and emerges as an aerosol or mist.
The concepts of aerosol probably go as far back as 1790. [1] The first aerosol spray can patent was granted in Oslo in 1927 to Erik Rotheim, a Norwegian chemical engineer, [1] [2] and a United States patent was granted for the invention in 1931. [3] The patent rights were sold to a United States company for 100,000 Norwegian kroner. [4] The Norwegian Postal Service, Posten Norge, celebrated the invention by issuing a stamp in 1998.
In 1939, American Julian S. Kahn received a patent for a disposable spray can, [5] [6] but the product remained largely undeveloped. Kahn's idea was to mix cream and a propellant from two sources to make whipped cream at home—not a true aerosol in that sense. Moreover, in 1949, he disclaimed his first four claims, which were the foundation of his following patent claims.
It was not until 1941 that the aerosol spray can was first put to effective use by Americans Lyle Goodhue and William Sullivan of the United States Bureau of Entomology and Plant Quarantine, who are credited as the inventors of the modern spray can. [7] [8] Their design of a refillable spray can, dubbed the aerosol bomb or bug bomb, is the ancestor of many commercial spray products. It was a hand-sized steel can charged with a liquefied gas under 75 pounds of pressure and a product to be expelled as a mist or a foam. [9] A public-service patent was issued on the invention and assigned to the Secretary of Agriculture for the free use of the people of the United States. [10] Pressurized by liquefied gas, which gave it propellant qualities, the small, portable can enabled soldiers to defend themselves against malaria-carrying mosquitoes by spraying inside tents and airplanes in the Pacific during World War II. [11] Goodhue and Sullivan received the first Erik Rotheim Gold Medal from the Federation of European Aerosol Associations on August 28, 1970, in Oslo, Norway in recognition of their early patents and subsequent pioneering work with aerosol sprays.
In 1948, three companies were granted licenses by the United States government to manufacture aerosol sprays. Two of the three companies, Chase Products Company and Claire Manufacturing, continue to manufacture aerosol sprays. The "crimp-on valve", used to control the spray in low-pressure aerosol sprays was developed in 1949 by Bronx machine shop proprietor Robert H. Abplanalp. [8] [12]
In 1974, Drs. Frank Sherwood Rowland and Mario J. Molina proposed that chlorofluorocarbons, used as propellants in aerosol sprays, contributed to the depletion of Earth's ozone layer. [13] In response to this theory, the U.S. Congress passed amendments to the Clean Air Act in 1977 authorizing the Environmental Protection Agency to regulate the presence of CFCs in the atmosphere. [14] The United Nations Environment Programme called for ozone layer research that same year, and, in 1981, authorized a global framework convention on ozone layer protection. [15] In 1985, Joe Farman, Brian G. Gardiner, and Jon Shanklin published the first scientific paper detailing the hole in the ozone layer. [16] That same year, the Vienna Convention was signed in response to the UN's authorization. Two years later, the Montreal Protocol, which regulated the production of CFCs was formally signed. It came into effect in 1989. [15] The U.S. formally phased out CFCs in 1995. [17]
If aerosol cans were simply filled with compressed gas, it would either need to be at a dangerously high pressure and require special pressure vessel design (like in gas cylinders), or the amount of payload in the can would be small, and rapidly deplete. Usually, the gas is the vapor of a liquid with boiling point slightly lower than room temperature. This means that inside the pressurized can, the vapor can exist in equilibrium with its bulk liquid at a pressure that is higher than atmospheric pressure (and able to expel the payload), but not dangerously high. As gas escapes, it is immediately replaced by evaporating liquid. Since the propellant exists in liquid form in the can, it should be miscible with the payload or dissolved in the payload. In gas dusters and freeze sprays, the payload itself acts as the propellant. The propellant in a gas duster can is not "compressed air" as sometimes assumed, but usually a haloalkane.
Chlorofluorocarbons (CFCs) were once often used as propellants, [18] but since the Montreal Protocol came into force in 1989, they have been replaced in nearly every country due to the negative effects CFCs have on Earth's ozone layer. The most common replacements of CFCs are mixtures of volatile hydrocarbons, typically propane, n-butane and isobutane. [19] Dimethyl ether (DME) and methyl ethyl ether are also used. All these have the disadvantage of being flammable. Nitrous oxide and carbon dioxide are also used as propellants to deliver foodstuffs (for example, whipped cream and cooking spray). Medicinal aerosols such as asthma inhalers use hydrofluoroalkanes (HFA): either HFA 134a (1,1,1,2,-tetrafluoroethane) or HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) or combinations of the two. More recently, liquid hydrofluoroolefin (HFO) propellants have become more widely adopted in aerosol systems due to their relatively low vapor pressure, low global warming potential (GWP), and nonflammability. [20] Manual pump sprays can be used as an alternative to a stored propellant.
Liquid aerosol propellant filling machines require additional precautions, such as being mounted externally to the production warehouse in a gas house. Liquid aerosol propellant machines are typically constructed to comply with ATEX Zone II/2G regulations (classification Zone 1). [21]
Modern aerosol spray products have three major parts: the can, the valve and the actuator or button. The can is most commonly lacquered tinplate (steel with a layer of tin) and may be made of two or three pieces of metal crimped together. Aluminium cans are also common and are generally used for products that are more expensive or intended to have a more premium appearance, such as personal care products. The valve is crimped to the inside rim of the can, and the design of this component is important in determining the spray rate. The actuator is depressed by the user to open the valve; a spring closes the valve again when it is released. The shape and size of the nozzle in the actuator controls the aerosolized particle size and the spread of the aerosol spray. [22]
True aerosol sprays release their propellant during use. [2] [3] Some non-propellant alternatives include various spray bottles, squeeze bottles, and Bag on Valve (BoV) or Bag in Can (BiC) compressed gas aerosol systems.
Packaging that uses a piston barrier system by CCL Industries or EarthSafe by Crown Holdings is often selected for highly viscous products such as post-foaming hair gels, thick creams and lotions, food spreads and industrial products and sealants. The main benefit of this system is that it eliminates gas permeation and assures separation of the product from the propellant, maintaining the purity and integrity of the formulation throughout its consumer lifespan. The piston barrier system also provides a consistent flow rate with minimal product retention.
Another type of dispensing system is the bag-in-can (or BOV, bag-on-valve technology) system where the product is separated from the pressurizing agent with a hermetically sealed, multi-layered laminated pouch, which maintains complete formulation integrity so only pure product is dispensed. [23] Among its many benefits, the bag-in-can system extends a product's shelf life, is suitable for all-attitude, (360-degree) dispensing, quiet and non-chilling discharge. One key performance difference relative to true aerosol systems is that traditional BoV dispensing pressures, BoVs pressurized solely by pressurized gas) drops as the product is dispensed. This bag-in-can system is used in the packaging of pharmaceutical, industrial, household, pet care and other products that require complete separation between the product and the propellant or require near complete evacuation of thin to viscous formulations.
A later development is the 2K (two component) aerosol spray, with a main component stored in a main chamber, and a second component stored in an accessory container. When an applicator activates the 2K aerosol by breaking the accessory container, the two components mix. The 2K aerosol can is advantageous for delivery of reactive mixtures; for example, a 2K reactive mixture can use low molecular weight monomer, oligomer, and functionalized low molecular polymer to make a final cross-linked high molecular weight polymer. A 2K aerosol can increase solid contents and deliver high-performance polymer products, such as curable paints, foams, and adhesives.
Aerosol cans have three main areas of health concern:
In the United States, non-empty aerosol cans are considered hazardous waste, [26] but are still considered "recyclable when empty" in US curbside recycling programs. [29]
Aerosol products in the European Union must comply with health and safety regulations as set out in Directive 75/324/EEC. [30] which established the "reversed epsilon" mark. [lower-alpha 1] This marking is required for aerosol products over 50ml. [31] The same marking is also used in the United Kingdom, although the UKCA marking is planned to replace it in Great Britain. [32]
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propane.
Freon is a registered trademark of the Chemours Company and generic descriptor for a number of halocarbon products. They are stable, nonflammable, low toxicity gases or liquids which have generally been used as refrigerants and as aerosol propellants. These include chlorofluorocarbons and hydrofluorocarbons, both of which cause ozone depletion and contribute to global warming. 'Freon' is the brand name for the refrigerants R-12, R-13B1, R-22, R-410A, R-502, and R-503 manufactured by The Chemours Company, and so is not used to label all refrigerants of this type. They emit a strong smell similar to acetone. Freon has been found to cause damage to human health when inhaled in large amounts. Studies have been conducted in the pursuit to find beneficial reuses for gases under the Freon umbrella as an alternative to disposal of the gas.
A propellant is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the engine that expels the propellant is called a reaction engine. Although technically a propellant is the reaction mass used to create thrust, the term "propellant" is often used to describe a substance which contains both the reaction mass and the fuel that holds the energy used to accelerate the reaction mass. For example, the term "propellant" is often used in chemical rocket design to describe a combined fuel/propellant, although the propellants should not be confused with the fuel that is used by an engine to produce the energy that expels the propellant. Even though the byproducts of substances used as fuel are also often used as a reaction mass to create the thrust, such as with a chemical rocket engine, propellant and fuel are two distinct concepts.
Liquefied petroleum gas, also referred to as liquid petroleum gas, is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, n-butane and isobutane. It can sometimes contain some propylene, butylene, and isobutene.
In medicine, a nebulizer or nebuliser is a drug delivery device used to administer medication in the form of a mist inhaled into the lungs. Nebulizers are commonly used for the treatment of asthma, cystic fibrosis, COPD and other respiratory diseases or disorders. They use oxygen, compressed air or ultrasonic power to break up solutions and suspensions into small aerosol droplets that are inhaled from the mouthpiece of the device. An aerosol is a mixture of gas and solid or liquid particles.
Air fresheners are products designed to reduce unwanted odors in indoor spaces, or to introduce pleasant fragrances, or both. They typically emit fragrance to mask odors but may use other methods of action such as absorbing, bonding to, or chemically altering compounds in the air that produce smells, killing organisms that produce smells, or disrupting the sense of smell to reduce perception of unpleasant smells.
Shaving cream or shave cream is a category of cream cosmetics used for shaving preparation. The purpose of shaving cream is to soften the hair by providing lubrication.
Dichlorodifluoromethane (R-12) is a colorless gas usually sold under the brand name Freon-12, and a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant. In compliance with the Montreal Protocol, its manufacture was banned in developed countries in 1996, and in developing countries in 2010 out of concerns about its damaging effect on the ozone layer. Its only allowed usage is as a fire retardant in submarines and aircraft. It is soluble in many organic solvents. R-12 cylinders are colored white.
1,1,1,2-Tetrafluoroethane (also known as norflurane (INN), R-134a, Klea 134a, Freon 134a, Forane 134a, Genetron 134a, Green Gas, Florasol 134a, Suva 134a, HFA-134a, or HFC-134a) is a hydrofluorocarbon (HFC) and haloalkane refrigerant with thermodynamic properties similar to R-12 (dichlorodifluoromethane) but with insignificant ozone depletion potential and a lower 100-year global warming potential (1,430, compared to R-12's GWP of 10,900). It has the formula CF3CH2F and a boiling point of −26.3 °C (−15.34 °F) at atmospheric pressure. R-134a cylinders are colored light blue. A phaseout and transition to HFO-1234yf and other refrigerants, with GWPs similar to CO2, began in 2012 within the automotive market.
Hair spray is a common cosmetic hairstyling product that is sprayed onto hair to protect against humidity and wind and have it stay in a desired shape. Hair sprays typically consist of several components for the hair as well as a propellant.
Spray paint is paint that comes in a sealed, pressurized container and is released in an aerosol spray when a valve button is depressed. The propellant is what the container of pressurized gas is called. When the pressure holding the gas is released through the valve, the aerosol paint releases as a fine spray. Aerosol painting is one form of spray painting; it leaves a smooth, even coat, unlike many traditional rolled and brushed paints. Aerosol primer can be applied directly to bare metal and many plastics.
A gas duster, also known as tinned wind or compressed air, is a product used for cleaning or dusting electronic equipment and other sensitive devices that cannot be cleaned using water.
Robert Henry Abplanalp, (KHS) was an American inventor and engineer who invented the modern form of the aerosol spray valve, the founder of Precision Valve Corporation, a Republican political activist, and a close confidant of Richard Nixon.
A packaging gas is used to pack sensitive materials such as food into a modified atmosphere environment. The gas used is usually inert, or of a nature that protects the integrity of the packaged goods, inhibiting unwanted chemical reactions such as food spoilage or oxidation. Some may also serve as a propellant for aerosol sprays like cans of whipped cream. For packaging food, the use of various gases is approved by regulatory organisations.
A metered-dose inhaler (MDI) is a device that delivers a specific amount of medication to the lungs in the form of a short burst of aerosolized medicine that is usually self-administered by the patient via inhalation. It is the most commonly used delivery system for treating asthma, chronic obstructive pulmonary disease (COPD) and other respiratory diseases. The medication in a metered dose inhaler is most commonly a bronchodilator, corticosteroid or a combination of both for treating asthma and COPD. Other medications less commonly used but also administered by MDI are mast cell stabilizers, such as cromoglicate or nedocromil.
An icemaker, ice generator, or ice machine may refer to either a consumer device for making ice, found inside a home freezer; a stand-alone appliance for making ice, or an industrial machine for making ice on a large scale. The term "ice machine" usually refers to the stand-alone appliance.
Silly String is a toy of flexible, sometimes brightly colored, plastic string propelled as a stream of liquid from an aerosol can. The solvent in the string quickly evaporates in mid-air, creating a continuous strand. Silly String is often used during weddings, birthday parties, carnivals and other festive occasions, and has also been used by the US military to detect tripwires.
Reddi-Wip is an American brand of sweetened whipped cream propelled from its container by nitrous oxide. It is produced by Conagra Brands and is sold in varieties such as Original, Extra Creamy, Fat Free, Zero Sugar, and Barista. In 2019, two new plant-based varieties, Non-Dairy Coconut and Non-Dairy Almond, were released. Both products are dairy-free and plant-based.
Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS), in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air conditioning of buildings and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage of foods and meats, refrigerated trucks and railroad cars, and a host of other commercial and industrial services. Oil refineries, petrochemical and chemical processing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems. Cascade refrigeration systems may also be implemented using two compressors.
Erik Andreas Rotheim was a Norwegian professional chemical engineer and inventor. He is best known for invention of the first aerosol spray can and valve that could hold and dispense fluids.
Sprayboksens far er norsk;Erik Rotheim fant opp aerosolflasken, sprayboksen, på 1920-tallet. I 1927 tok han patent på oppfinnelsen. [...] og patentet ble etterhvert solgt til et amerikansk selskap for 100 000 kroner. | The Father of the Spraybox is Norwegian;Erik Rotheim invented the aerosol bottle, the spray box, in the 1920s. In 1927, he patented the invention. [...] the patent was eventually sold to a US company for NOK 100,000. |
Freon chemical compounds in household refrigerators, air-cooling systems and as a DDT carrier in aerosol insect bombs have been found to be more effective in extinguishing fires than carbon dioxide.
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