The aerosol marketplace is always looking for innovation. Consumers demand it, and competition is always a friend to innovation where it allows a gain in market share. Although the plastic container has been elusive as an aerosol container, it is now expected in the marketplace. While our customers and consumers will invariably adopt new innovative products and accept the advantages that aerosols have delivered for decades, plastic is an opportunity to bring a new look with new advantages to the marketplace. As an industry, and within the global marketplace, aerosol products need to evolve to meet the needs of our consumers in order to remain at the forefront of innovation.
The aerosol industry is growing and expanding into new nations and markets every year. At about 13 billion units annually, diversifying our container portfolio will continue this growth trend. This is critical to stay the tide of market pressure from less regulated products. Plastic aerosol containers represent a platform from which to show consumers new innovative design options or showcase completely new products.
Setting the Stage
Options for plastic aerosol containers are now more specified, giving the industry a clear process toward the marketplace. One of the original standards for modern plastic aerosol packaging is British Standard BS 5597:1991, created by a committee for the Packaging Freight Containers Standards Policy Committee in 1991. This standard laid the recent framework for inventors to utilize in the development of a plastic aerosol container. Although several attempts to market plastic aerosol containers were initiated in the 1960s, none have sustained shelf presence until recently.
A significant driver allowing today’s plastic aerosol container is the technical evolution in the injection stretch blow molding (ISBM) process. ISBM improvements to support the conversion of carbonated soft drinks out of glass and into plastic significantly drove the quality and consistency of wall orientation and other process controls that are now being leveraged into the aerosol bottle. Leveraging the improvements in the ISBM bottle manufacturing process, several companies have worked to develop aerosol bottles. These aerosol bottles supported the request of a “Special Permit” (SP) allowing the distribution of plastic aerosol containers to the U.S. Dept. of Transportation (DOT) Pipeline & Hazardous Materials Safety Administration (PHMSA). The PHMSA decided in 2009 to amend section 173 of the Federal Register (Vol. 74) permitting distribution of plastic aerosol containers. Discussion within the code-change preamble is the understanding that the ISBM technology has advanced and that there was no evidence that an issue had been seen in the SPs for plastic aerosol containers to date.
Within the discussion of this amendment it is argued that approval of plastic
aerosol containers would also help “enhance international harmonization and provide relief to the regulated community by removing the need for specialpermits”. In this code change, PHSMA set the parameters for a non-specified and anew “2S” specified bottle. Included in the PHMSA code are specifications concerning the shipping papers, labeling, marking and packaging requirements for transportation of plastic aerosol containers. Retaining focus on the container, we can pull from the PHSMA literature characteristics necessary for the distribution of a plastic aerosol. The overriding responsibility is to assure equivalent safety in the marketplace as authorized packaging. General provisions constrain the non-refillable aerosol container to a maximum diameter of 3″, capacity to one liter (1000ml) and pressure to a maximum of 160 psig at 130°F.
Pulling directly from PHSMA 49 CFR these areas should be considered:
(a) Each container must be manufactured by thermoplastic processes that will assure uniformity of the completed container. No used material other than production residues or regrind from the same manufacturing process may be used. The packaging must be adequately resistant to aging and to degradation caused either by the substance contained or by ultraviolet radiation.
178.33b–7 Design Qualification Test.
(a) Drop Testing.
(1) To ensure that creep does not affect the ability of the container type to retain the contents, each container type shall be drop tested as follows: three groups of twenty-five filled containers shall be dropped from 1.8m on to a rigid, non-resilient, flat and horizontal surface. One group must be conditioned at 38 °C (100 °F) for 26 weeks, the second group for 100 hours at 50 °C (122°F) and the third group for 18 hours at 55 °C (131 °F), prior to performing the drop test. (2) Criteria for passing the drop test: the containers must not break or leak.
§ 178.33b–8 Production Tests.
(a) Burst Testing.
(1) One out of each lot of 5,000 containers or less, successively produced per day must be pressure tested to destruction and must not burst below 240 psig. The container tested must be complete as intended for transportation.
(2) Each such 5,000 containers or less, successively produced per day, shall constitute a lot and if the test container shall fail, the lot shall be rejected or ten additional containers may be selected at random and subjected to the test under which failure occurred. These containers shall be complete as intended for transportation. Should any of the ten containers thus tested fail, the entire lot must be rejected. All containers constituting a lot shall be of like material, size, design construction, finish, and quality.
(b) Leak Testing. (1) Each empty container must be subjected to a pressure equal to or in excess of the maximum expected in the filled containers at 55 °C (131 °F) or 50 °C (122 °F) if the liquid phase does not exceed 95 percent of the capacity of the container at 50 °C (122 °F). This must be at least two-thirds of the design.
Moreover, these requirements were derived in an effort to assure each container is robust. The time frame and breadth of testing is rigorous. Of course, each manufacturer or marketer must review the most current regulations managing products placed into the marketplace in order to retain the high standards of products in the marketplace today.
Manufacture & Storage of a Plastic Aerosol Container
Just because one arm of the regulatory process moves its position doesn’t assure that coordination across regulating bodies can be anticipated. The PHMSA modifications were a boost to the distribution of plastic aerosol containers. However, as important as this move was to the industry, it wasn’t all-inclusive. The PHSMA provided direction toward distribution, but codes for the manufacture and storage retained earlier limitations.
Realizing the inconsistency in code modifications, industry engaged to assist in development of data that would help direct the code-setting bodies for manufacturing and storage codes. To this end, the Plastic Aerosol Research Group, LLC, (PARG) was formed through the Consumer Specialty Products Association (CSPA) Product Ingredient Review (PIR) program. PARG was chartered to engage with industry experts at the National Fire Protection Association (NFPA) and United Laboratories (UL), among others, to determine what would be needed to support code change.
PARG constructed and executed a testing plan to assure good science was employed in the determination of what product/package combinations could be managed by the majority of fire safety systems currently in place for aerosol product storage facilities. In this initial testing scheme, an array of products were fire tested in plastic containers. The products ranged across heats of combustion and propellant concentrations with and without bag-on-valve (BOV) options inside the test variables. The results of these fire tests and other large volume fire tests shared with PARG were compiled and shared with the CSPA. Data from the PARG testing showed the ability to manage a set of product package formulations.
With this data in hand, PARG showed that products with a low order of flammability could safely move to the marketplace. With the advocacy of CSPA, the industry proposed amendments to NFPA 30B and the International Code Council (ICC) through the International Fire Code Council (IFC) authorities. Paramount across code authorities were concerns around the product formulations within a plastic aerosol container and potential for management of a fire event. A white paper was developed showing the results of the fire testing performed and this data was shared with NFPA and IFC/ICC code officials.
At this time the PARG requested code modifications have received initial concurrence across NFPA and ICC/IFC. Principle criteria for storage are based upon a reduction in flammability and specifically need to meet these requirements.
Aerosol products in plastic containers larger than 118 ml (4 fl. oz.) shall be considered to be equivalent to Class III commodities, as defined in NFPA 13, Standard for the Installation of Sprinkler Systems, where any of the following conditions are met:
(a) Base product has no fire point when tested in accordance with ASTM D 92, Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester, and nonflammable propellant.
(b) Base product has no sustained combustion as tested in accordance with “Method of Testing for Sustained Combustibility”, Title 49 Code of Federal Regulations, Part 173, Appendix H and nonflammable propellant.
(c) Base product contains up to 20% by volume (15.8% by weight) of ethanol and/or isopropyl alcohol in an aqueous mix and nonflammable propellant.
(d) Base product contains 4% by weight or less of an emulsified flammable liquefied gas propellant within an aqueous base. The propellant shall remain emulsified for the life of the product. Where such propellant is not permanently emulsified then the propellant shall be nonflammable.
Now we have a set of requirements in place for manufacture, storage and distribution of plastic aerosol containers. PARG will continue to develop data supporting new products as the industry innovates with the plastic package.
North American Industry Opportunity
At this point in the process, we have a path to production, distribution and storage of an aerosol product utilizing a plastic container. Products are on the shelf today in a very limited capacity. As the code modifications progress, we can anticipate more suppliers and marketers on the shelf.
This is especially true in the North American (NA) marketplace. Evidence of plastic aerosol containers in North America can be traced back to the 1950s, but few have secured a long-term presence (see SPRAY, April 2009). One example of a plastic aerosol container is Procter & Gamble’s Oral-B Brand dental professional fluoride aerosol mousse product. The plastic container utilizes a standard outside crimp valve with a mousse spout. Shipped via professional channels, the product shows long term stability and market success. A few other plastic aerosol bottles can be found in the U.S. marketplace, although we should anticipate more products in the near future. So how will the new products show up?
We should anticipate bottles utilizing standard valve systems, as well as bottles incorporating the BOV system. These packaging options would be consistent with the current metal container options. Plastic aerosol containers also have a piston option for the marketplace. Airopack (see following page) has introduced a plastic aerosol innovation that separates the product and propellant in a piston system. The key to this technology is the incorporation of a patented valving system that manages the pressure between the product cavity and the propellant container. This valve permits a more consistent pressure delivery during the life of the unit. The pressure-containing vessel is at several bar but the valve manages the product-containing area to a desired functioning pressure. Pressure is the primary variable to manage across this package, as is the case in most aerosol systems. Where aerosol products dictate a specific container style in metal, an equivalent option appears to be available in plastic.
Searching for plastic containers outside of the NA marketplace, we see more products on the store shelves. Today, most plastic aerosol products are found in the European marketplace where plastic aerosol containers are currently permitted. These products comply with the current European Aerosol Dispenser Directive (ADD). Current allowance by the ADD is 50-220ml volume, which has permitted products such as Wella’s Salon Professional Mousse to see the market for several years. Other plastic aerosol products have also recently advanced to the European market such as Balea Shave Foam. The European Union (EU) aerosol community is in the process of requesting the European Commission to modify the ADD regulations (see Plastic Aerosols—situation and prospects. Aerosol Europe Vol. 21. 7/8-2013), and these changes will bring global regulations closer, but not equivalent.
Proposed changes to ADD in the EU, if adopted, will increase both the volume (up to 1000ml) and the internal pressure (up to 15 bar for aerosols using non-flammable propellants). There are equivalent requirements in the U.S. as far as drop impact testing, but the restrictions on the flammability characteristics of the product formulation is not consistent between the EU and the U.S. Yet you need to review, understand and follow all of the regional requirements. We also see plastic aerosol containers on the market in Asia and Latin America. We will need to watch how the regulatory requirements evolve in these and other growing aerosol markets.
Barriers to the marketplace
The regulatory enviroment can be a barrier to the marketplace. Once we understand the regional regulatory requirements, we need to then assure freedom to practice.
Intellectual property is another area for the innovator to manage. Patent publications focused on plastic aerosols were rather slow during the 1990s, averaging only about five per year. During the first decade of the 2000s, patent publications focused on plastic aerosols jumped to an averaged 20 per year. This four-fold increase is interesting to understand, as these publications mostly pertain to a more robust knowledge in the blow molding process and materials understanding.
The knowledge necessary to create high pressure thermoplastic bottles that overcome the earlier issues peaked in 2006. The U.S. has lead the way, with the UK and Japan following. Upon review of the patents related to plastic aerosols, the Base, Neck and Body are primary variables. Base geometry (petaloid, hemispherical and champagne) has been described for pressure retention and uniformity. Neck designs and material characteristics are provided to manage growth due to pressure or environmental conditions.
The body of the plastic container has been discussed with respect to pressure management and permeability. While each container will typically provide each component (base, neck and body), the innovator needs to consider earlier work to assure freedom to practice each final design. In order to not repeat others’ past mistakes, become familiar with the innovation history of intellectual property.
The elegance of evolution