Chemistry & Industry: June 2005

The US Environmental Protection Agency has granted AgION Technologies, the go-ahead to incorporate its antimicrobial coatings additive, Silver Copper Zeolite, into heating, ventilation and air conditioning (HVAC) systems and components. In addition, the agency extended the use of this powerful antimicrobial in textile, coating and plastic applications. This stamp of approval further demonstrates the compelling effectiveness of AgION’s antimicrobial technology.

According to the EPA report, silver antimicrobial coatings inhibit the surface growth of mold, mildew, fungus, and bacteria that cause odor, discoloration, staining, and corrosion. When the antimicrobial additive is incorporated into HVAC products and components, ‘it inhibits the growth of mold, mildew, fungus and bacteria that cause odor, discoloration, staining, deterioration or corrosions on the surface of the coating film.’

“Obtaining the EPA approval for the use of AgION’s antimicrobial technology in heating, ventilation, and air conditioning products offers the HVAC industry tremendous growth opportunities,” according to Ladd Greeno, president and chief executive officer of AgION Technologies, Inc. “The approval allows industry manufacturers to use our Silver Copper Zeolite Antimicrobial product in HVAC systems and related materials such as ducts, drain pans and air filters. These applications will benefit many users -- from homeowners to business and industry.”

The active ingredient of AgION antimicrobial technology is silver, which is historically recognized for its abilities to fight a broad range of microorganisms. By bonding silver to zeolite (a ceramic material that acts as a delivery system) particles, AgION’s silver copper zeolite technology destroys bacteria and suppresses future contamination. This ionic combination provides continuous, controlled-release of the silver over a long period of time.

According to Paul Ford, AgION’s corporate and regulatory counsel, the EPA approval is very significant. “Each time the EPA reviews the effectiveness and safety of the AgION antimicrobial technology and approves its use in certain industry applications, it further acknowledges the value of using AgION’s antimicrobial technology in coatings and product,” said Ford. “Because silver is non-toxic it is safe and effective against hundreds of different microorganisms, inhibiting cell respiration and reproduction and interrupting cell metabolism. Using antimicrobial resistant technologies in HVAC systems, as well as in textile and coatings industry applications increases the value of these product in the marketplace.”

The agency also amended a previous authorization, saying that further use of AgION’s Silver Copper Zeolite Antimicrobial Technology in plastic, textile and coating applications is acceptable because it provides additional safety protection against microbial contaminants. These extended approvals allow manufacturers of products such as fibers, films, laminates, adhesives and sealants to increase the amount of AgION’s antimicrobial they use in a wide array of commodities, adding further protection from the growth of algae, mold, mildew, fungi, and bacteria.

AgION Technologies, located in Wakefield, MA, is an international leader in providing engineered antimicrobial solutions that continuously inhibit the growth of bacteria, mold and fungus on a broad range of industrial, consumer and medical products.


Chemical Marketing Reporter: June 2005

If necessity is the mother of invention, then the European Biocidal Product Directive (BPD) has forced biocides producers to be inventive. Introduced in 2000—and expected to be fully implemented by 2010—the BPD’s key purpose is to review the active ingredients of formulated biocidal products. To date, a number of active ingredients have already been removed from the marketplace because of the BPD.

“The number of biocides supported for the BPD represents roughly one-third of the total number available to paint and coatings companies 10 years ago,” says Donald Shaw, Troy Corp.’s vice president of development. “Additional labeling requirements to this group of biocides will further reduce the choices available to paint and coatings producers.”

“Worldwide, the number of available biocides and the flexibility to react to special technical requirements are compromised by the review program associated with the European BPD, as well as other regulatory requirements growing in new countries,” says Eric Bensaid, Troy’s senior vice president of sales and marketing. “In Europe, many paint and coatings manufacturers are finding it difficult to deal with both an emerging EU regulatory system and the implementation of new regulatory schemes in the various member states.”

“With the regulatory environment the way it is today, particularly in the US and especially in Europe with its BPD, what we’re being forced to do in this industry as we look for new ways to solve microbial problems is to go back to established biocides with good solid registrations and work on new ways to apply those biocides to solve more stubborn problems,” says Mark Henning, president and CEO of Angus Chemical Company, and the general manager of Dow Biocides.

At the beginning of the month, Dow Biocides introduced benzisothiazolinone (BIT) to its product portfolio. “BIT is a new molecule for Dow Biocides’ portfolio, although it is a well-established molecule for the biocides industry,” adds Henning. “It has been used for quite a long time in paints and coatings as an in-can preservative and in metal-working fluids as an antimicrobial agent. It is very well established, has good registration and an excellent toxicity profile.”

Henning notes that Dow Biocides looks over several options while considering a new molecule, including in-house development, tolling or purchasing. “In BIT’s case, we are not manufacturing it,” says Henning. “We found what we believe is the most competitive supplier of a high-quality, well-registered material in the marketplace, and Dow is sourcing the material from them.”

BIT “strengthens the options in our portfolio for greater application flexibility,” says Henning. The company has been developing its BIT project for about one year, spurred on by customers seeking “new and novel solutions.”

While a single active ingredient may be sufficient to protect a coating against in-can spoilage or dry-film defacement, usually it is recommended that a blend of actives be used, so that a synergy of ingredients can be achieved: Because about 80 percent of architectural paints are waterborne, they are very susceptible to microbial attack, in both the wet and dry states.

Little Falls, N.J.-based consultancy Kline & Company Inc. estimates the global market for biocides at $3.63 billion, with the US accounting for 45 percent and 20 percent coming from Western Europe. Cleveland-based consultancy Freedonia Group Inc. projects that US demand for biocides will increase by 4.8 percent annually to $2.35 billion by 2008.

East Hardwick, Vt.-based C&M Consulting estimates that North American consumption of biocides in paints was in the range of $100 million to $120 million in 2002. “Biocides growth is generally going to follow the rate of industrial development because that is where industrial biocides are going to play a part,” says Henning.

Consolidation is a major theme in the biocides market, according to C&M Consulting. Over the past several years, Rohm and Haas acquired Swiss biocide producer Acima, Troy purchased the German producer Riedel de Haen, Dow bought Angus Chemical and then merged with Union Carbide, Bayer acquired two biocide chemistries from Ondeo Nalco. In 2004, Arch Chemicals purchased the biocides business of Avecia, and International Specialty Products purchased German preservative formulator Biochema Schwaben as well as Degussa’s biocide business.

Dow Biocides’ Henning says that no one company holds more than 5 percent of the industry’s market share. “The market is really calling for someone to take a leadership position—to consolidate an offering, to consolidate a portfolio, and to position themselves as a leader in solving microbial problems,” he says. “When Dow Biocides looks at the marketplace, we are looking at growth well beyond what the general market is going to do. If the market is growing at 4 to 5 percent, we are looking to grow Dow Biocides’ position in the marketplace at 10 to 15 percent on an annual basis.”


Asia Pacific Coatings: July 2005

Much has been written or presented about antimicrobial systems for surfaces application and many of the claims seem overrated such as “the answer to MRSA”. Dr Terence Child has reviewed and put into perspective the technologies available today for applications in hospitals and care homes.

It is a myth that antimicrobial surfaces are the single answer to infection control in hospitals and care homes. Claims that they are the Holy Grail to combat MRSA have damaged the credibility of technologies that are available from reputable companies who are aware of the place for antimicrobial surfaces within an infection control programme. This paper was written following an in-depth review of technical papers, patents, company literature, trade articles and discussion with manufactures and infection control nurses. It provides a balanced view of the technologies available, shows their essential differences and indicates where successful applications have been made.

Major Categories

There are two major categories of antimicrobial surfaces, those resulting from the incorporation of the biocide throughout the whole of article and those with only surface coatings. Examples of totally incorporated biocides would be impregnated materials such as plastics and laminates. Surfaces coatings could in the form of paints, or special applications involving spraying, padding or dipping.

Efficacy and Durability

Claims are varied. A disinfective action is claimed by some system whereas a biostatic action is claimed by most well-established products on the market. None of the claims may be compared directly because there is no internationally recognised performance standard for evaluating antimicrobial surfaces. An internet review of claims for durability shows a vast range, from 7 days to 30 years, depending on the type of product. Paints based on polyurethanes, epoxy materials or styrene acrylics claim, on average, have a 10 year lifespan.

Application Areas

Paints have been used for coatings many areas such as walls, ceilings and floors. Addition of biocides to powder coating treatment has found application in items such as shelving and bed frames. A variety of biocidal treatments has been used for clothing, kitchen utensils, medical devices, bandages, surgical instruments and implants.

Totally embedded versus surface coated systems

Objects with biocide distributed throughout the body of the material rely on the surface population of biocides to provide antimicrobial effect. The biocides are tied into polymer matrix in a manner which is not completely understood and some migration can occur. The biocides on the surface are fixed and therefore enable food contact approvals and compliance with the Medical Products Directive. In the event of abrasion or wear over a period of time, a degree of self-repair is possible by exposing more biocidal material from beneath the surface. The biocidal action will therefore remain for the lifetime of the product.

The concentration of biocide within the material is an important factor; very high levels will increase rate of kill but may preclude food contact or direct body-fluid contact; levels which are too low may make the surface ineffective, or worse, encourage the growth of resistant strains.

Surface coatings are preferably of the type with the biocide fixed to a thin polymer film thus providing a biostatic action. There is no release of biocide and therefore the surface is not-toxic and non-tainting and the surface activity will be constant unless badly soiled.

Other coating products are available on the market which claim a disinfection action by allowing biocides, or combinations of biocides, to leach out of the polymer film onto the surface. Although this provides a more rapid kill rate, the product will be more toxic to humans and the reservoir of biocide is soon used up, requiring reapplication after a number of days.

Performance standards

There are no internationally recognised standards for evaluating antimicrobial surfaces which makes comparison of data difficult or impossible. This has been recognised in the industry and a standard is being formulated through an OECD funded initiative which will provide a definitive test protocol by the middle of 2005. The test method will be based on Japanese Industry Standard (JIS Z 2801:2000) and a schematic of the method is indicated below.

The method involves inoculating a test piece and then covering the area with a polyethylene film. The sandwiched cell suspension is incubated for 24 hours, transferred to neutraliser and TVC determined in the normal way.

The method has been used to make comparative evaluations of several antimicrobial surfaces. In the results shown below, six different antimicrobial surfaces were inoculated with Staphylococcus aureus. Untreated stainless steel and film from a stomacher bag (used in the food industry) were included as standards.

Materials 1 and 2 showed a good disinfection action after 18 hours contact time and materials 3 and 4 showed reasonable log reductions of 3-4.

Materials 5 and 6 were not very effective and material 6 showed behaviour similar to the untreated standards. The method, when finalised, will provide a powerful tool in comparing the effectiveness of antimicrobial surfaces. Later stages of the method development will involve introduction of surface soiling.

Well-established technologies

In selecting technologies for more detailed description, it is important to consider those with a well-established history of application in the health care sector. These will have undergone extensive safety testing and several new applications will have been developed over the years. Three technologies have been used for a minimum of 20 years in medical applications and each is different in principle although with some overlap:

·              Silver ion technology

·              Organic biocides in coatings or incorporated into objects

·              Cationic biocides covalently bonded to a reactive silicone compound.

Silver technology

In its simplest form, a coating system is formed by binding silver ions to a fine ceramic powder (zeolite), dispersed in a carrier. The ions are then exchanged with sodium, calcium or other ions when the surface comes into contact with water body fluids. Further developments, particularly in the area of nanotechnology, have enabled the use of silver technology in plastics, fabrics, and coatings without the use of zeolite.

Uptake of silver ions by a cell can occur by several mechanisms, including passive diffusion and active transport by systems that normally transport essential ions. While the silver ions may bind non-specifically to cell surfaces and cause disruptions in cellular membrane function, it is widely believed that the antimicrobial properties of silver depend on silver binding within the cell. Once inside the cell, silver ions begin to interrupt critical functions of the micro-organism.

Applications of silver ion technology

A review of applications shows that this technology has been used in the following health care areas: treatment of steel ducting and components in HVAC systems, building materials, carpets, cubicle curtains, lockers, safety cabinets, bedpans, sack holders, soap dispensers, keypads, medical devices, wound dressings and implants.

Antimicrobial paint containing silver ions was used during the phase 4 development at St. James’ Hospital, Leeds. A high performance coating was applied to all operating theatre walls, in order to provide long-term protection against the growth of bacteria, mould and other micro-organisms.

Organic Biocides

Organic biocides may be incorporated into plastic and fabrics during the manufacturing stage. For plastics, the biocide added into the manufacturer’s virgin resin, blended, melted, then moulded or extruded into the final article. For fabrics, the biocide may be incorporated in several different ways according to the method of manufacture.

Usually the biocide is applied by foaming, padding or spraying. The innovative aspect of this technology is the nature of the interaction of the biocide with the polymer of fibre matrix. In plastics, this should provide a fixed population of the active ingredient on the surface of the article, without affecting “feel” of the fabric. The biocide must remain durable and not be washed out during normal laundering.

The concentration of biocide is optimised to provide adequate protection, without the dangers of under or overdosing. Many different organic biocides are now in use, some specially selected for specific applications. Some of the earliest applications involved combating the growth of odour-causing bacteria on medical devices.

Application of organic biocides

There are many applications in the building industry, for example in producing wall laminates for high risk areas in food processing and clean rooms.

In the hospital environment, applications include: bedding, bed frames; carts for transport of medication, liners, equipment and other supplies; hand rails, pulls, trims and door handles; slings and hoists; window blinds; dental trays; incise drapes; wound dressings; keyboards and mouse.

Covalent bonding of biocide to a reactive silicone compound

This technology utilises the properties of reactive silanols and their ability to form covalent bonds with a target surface. The silanols are modified with biocidal adjuncts, so that when silanols fix onto a surface, the active biocidal sites become fixed too. The films created are extremely thin, between 15 nm and 180nm, and therefore the original physical properties of the surface are little affected. Bacteria arriving on the surface encounter the hydrocarbon portion of the biocidal adjunct which may be assimilated into the cell without any disruption. However, contact with the positively charged nitrogen atom will unbalance the electrical equilibrium within the porin channels and on the outer protein layers such that the cells can no longer function correctly and the microbes will die.

The reactive silanols will form a covalent bond with any surface containing oxygen, nitrogen or carbon in any form. For example hydroxides or oxides on the surfaces of metals (including stainless steel) will form a durable bond. The application is therefore very versatile and types of surface may be treated, such as plastic, metal, fabric and painted surfaces.

Application of biocidal reactive silanols

The fixed nature of the biocide is important where toxicity, taint and other aspects are concerned.  This is a bacteriostatic surface treatment, not removed by normal cleaning procedures. In fact, it is important to maintain the normal cleaning regime in order to “refresh” the biocidal surface.

The thinness of the film enables application in areas where optical properties are important such as treatment of contact lenses. The technology has been used for treatment of bedsheets, hospital garments, curtains, floor and wall materials, air filtration system, medical devices, bandages, surgical instruments and implants. The technique has been used to prevent biofilm growth on catheters, stents, contact lenses and endotracheal tubes.

An actual case study in USA involved treatment of the entire building of the A.G. James Cancer Hospital/Ohio State University to reduce the incidence of allergies with mould sensitive individuals after a disastrous flood in the hospital.  Following application, a sharp reduction in the aeromicrobial level was observed. Significantly, even after two years, the average microbial count was less than 1 CFU.


It is important to state that antimicrobial coatings must not undermine the success of traditional hygiene methods and neither must conventional cleaning and hygiene operations be relaxed if antimicrobial coatings are employed. Indeed, this could become a downside of employing the technology should this occur. However, this study has highlighted that there could be a useful place for antimicrobial coatings as a complementary part of infection control programmes. Apart from specialised applications, such as treatment of medical devices or incorporation into fabrics for hospital garments, the treatment of large surface areas within hospitals and care homes, such as walls and floors, will reduce the risk of contaminated surfaces acting as a reservoir for organism transfer to humans. The choice of system will be determined by method of application intended and the type of location to be treated. Finally, performance claims should be backed up by an appropriate internationally recognised standard.


Chemical Week: June 2005

Thomson Research Associates (TRA) has introduced Ultra-Fresh Silpure, the new generation silver-based antimicrobial treatment for textiles. Ultra-Fresh Silpure enables textile manufacturers to add superior odor and fiber-degradation resistance to their products through the use of a powerful antimicrobial substance – metallic silver.

Ultra-Fresh Silpure, the newest development in the Ultra-Fresh® family of products, represents a breakthrough in the use of silver-based antimicrobials for the textile market. Ultra-Fresh Silpure is applied at the finishing stage for more complete protection of the fabric, and has been proven in tests to be consistently effective, with no tendency to cause discoloration.

The superior performance of this new generation silver-based antimicrobial has been achieved by combining application expertise developed over 50 years of Ultra-Fresh treatments with proprietary nanotechnology manufacturing processes for the metallic silver. The ultra-fine particles adhere more effectively to fibers for longer protection. Ultra-Fresh Silpure has broken the cost barriers which have restricted the use of silver- based antimicrobials in the past.

A natural antimicrobial

Silver containers have been used to keep their contents pure for centuries. Investigations into the ability of metallic silver to inhibit the growth of bacteria began in the late 19th century. The result was a number of pharmaceutical products intended as dressings for wounds and intreatment of eye infections, many of which are still in use. However, the cost of silver and the technical challenges of reducing the metal to the ultra-fine particles necessary for optimum performance limited its applications.

Ultra-Fresh Silpure promises ease of application for cost-effective use and long-lasting protection for optimal performance. Plant trials have established that antimicrobial performance of Ultra-Fresh Silpure remains strong after 50 or more washes -- a powerful benefit for consumers of sports and leisure wear. In plant trials, using typical application processes on 100% polyester fabrics, bacterial survival was less than 0.1%, even after 50 washes.

"Previous cost barriers to the wider use of silver have been overcome," says Dr. Laval Yau, president of TRA. "Now, silver antimicrobials are no longer confined to niche markets. They can be used effectively and profitably through the broadest range of consumer products."

The Ultra-Fresh brand, introduced by Thomson Research Associates is now used by more than 200 companies in more than 30 countries. Seen on a wide range of products and in magazine, radio and television advertising, the brand and its logo promise the highest standards of antimicrobial protection in clothing, household textiles, and many other applications.


Chemical Business News:  Jul 2005

Invision International Health Solutions announced the issuance of a US Patent on its "ionic silver complex" technology. The use of ionic silver in medicine and industry has been growing rapidly in recent years due to its broad-spectrum antimicrobial qualities, the lack of toxicity to humans and the fact that ionic silver is not prone to causing resistant strains. Ionic silver is well known to be a very powerful and very broad-spectrum antibacterial agent. In addition, evidence is mounting that silver ions have powerful antiviral effects as well. The patented technology is designed to utilize naturally occurring substances, such as citrate, to achieve optimal delivery and release of silver ions in the human body, in a highly efficient and entirely safe manner. Invision International Health Solutions is a company specializing in the research and development of ionic silver delivery solutions for human application. The company currently manufactures and markets a dietary supplement that consists of silver ions complexed with citrate and potassium in a water medium, the composition of which is covered under the patent.