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Biocides Update Preservation is Key



Good housekeeping is important, but adding the right preservative is critical to ensuring that a paint will last in the can and on the wall.



By Mike Agosta



Published August 10, 2005
Related Searches: Zero VOC Color Adhesives Low VOC
Customers generally take for granted that when they open a can of paint, it will be ready to apply, no questions asked. Most would probably neglect to even consider the possibility that any element of preservation is necessary. After all, it's just paint, right?

Coatings manufacturers and suppliers know that this is not the case. Like that can of mystery meat in the cupboard a number of preservatives must be added to paint and coatings to ensure that it will make it from the warehouse to its intended application. Of these preservatives, biocides, fungicides, algicides, mildewcides and antimicrobials lead the way.

The job of these products doesn't end in the can though. For many of these agents, the real work begins after the coating has been applied, helping to protect the substrate from mold, mildew and fungus.

This market segment will continue to grow not only monetarily, but in complexity as well. Regulation is tight in the biocide and antimicrobial market and rules are only getting more stringent.

Like all markets in the coatings industry, reduction of VOCs and meeting environmental regulations are some of the most oft-rendered phrases. "The move towards zero-VOC coatings systems continues to be a driver in the U.S.," said Alex Cornish, international marketing manager, preservation, at Avecia. "Outside the U.S., we are beginning to see the effects in the market of new European legislation concerning CMIT/MIT usage above 15 ppm which is resulting in customers moving away from CMIT/MIT or lowering the use level by mixing with other actives such as 1,2-benzisothiazolinone (BIT)."

The usual suspects? Here are some of the fungi that can attack coatings. Clockwise from top right: Aspergillus, Alternaria, Aureobasidium and another strain of Aspergillus.
photos: Buckman Laboratories, Inc.

Teresa Hoskins, North American regional marketing manager, Acima, agreed that VOC issues control the industry, stating that "As local regulations are driving them, paint manufacturers continue to focus on lowering VOC in their paint lines." In line with this, Acima has developed two preservatives, Rocima 550 and 607. Both are U.S. Environmental Protection Agency approved and registered for use in a variety of products, including water-based coatings such as paint, slurries, dispersed pigments, adhesives and latex emulsions. Rocima 550 is metal salt and APE free, and is highly recommended for systems with a pH greater than eight for in-can preservation. Rocima 607, also for in-can preservation, is low VOC and is also metal salt and APE free.

Proof of this trend towards low VOCs can be found in the new antimicrobial paints being released into the market. Miller Paint Co., Inc. recently launched a new line of interior paint that incorporates Microban antimicrobial product protection which inhibits the growth of bacteria, mold and mildew that can cause stains and odors on the dried paint film. Acro with Microban Protection, available in the Northwest U.S., represents a breakthrough in paint technology by providing all the high-performance characteristics of Miller Paint with extremely low VOCs, low odor, plus resistance to bacteria mold and mildew, according to the company.

Good Housekeeping
It's important to choose the right biocide to protect paint, but simply using an additive isn't enough to ensure that paint won't spoil. "Good housekeeping" is also an important means to prevent the growth of biocide tolerant strains, according to industry experts. According to Alex Cornish, international marketing manager, preservation, Avecia, there are a number of guidelines a coatings maker can follow to ensure against this. Formulators should:

1. Carry out laboratory checks to ensure that the biocide can preserve the product. This is done by carrying out bacterial challenge tests over a dose range using a selection of appropriate (e.g. common spoilage organisms and any "problem" organisms isolated from spoiled products)
2. Make sure that the biocide is stable in your product: don't rely only on microbiological data but carry out accelerated storage tests and underpin these using analytical measurements (e.g. HPLC).
3.  
  Make sure that you dose the biocide correctly: carry out biocide analysis (e.g. using HPLC) as part of your routine QC checks.
4. Carry out regular plant hygiene audits of the plant: this will enable you to identify bacterial hotspots in your process (e.g. high bioburden in the water supply, raw materials etc. and take appropriate action.
5. Clean pipework and tanks on a regular basis to prevent biofilm build up.
   

If spoilage is experienced, "you can always shock dose the systems with a more aggressive, quick kill biocide that does not on its own deliver long-term preservation," to kill the organisms," said Dr. Cornish.


Buckman Laboratories, Inc., has introduced new products recently that make use of BIT, in an effort to meet strict VOC regulations. The newest product from Buckman is Busan 1264, which is a 19.3% active 1,2 Benzoisothiazol-3(2H)-one. The company has also introduced a line of IPBC-based products, Busan 1420 (20% active), Busan 1440 (40% active) and Busan 1498 (98% active).

Also involving IPBC-based products, the plant and material protection division of Janssen Pharmaceuticals, N.V., headquartered in Belgium, and Troy Corporation, Florham Park, NJ, have entered into a cooperative agreement in the field of biocides protection for wood. According to Troy, the accord formalizes a successful ongoing cooperation between the two companies built on the strengths of their efficacious molecules, IPBC and Propiconazole. The agreement ensures that both companies maximize their ability to offer a comprehensive portfolio of complimentary active ingredients and preparations to the wood protection, coatings and metalworking fluids industries. Under the agreement, Troy and Janssen offer each other's active substances, formulated to specific uses and performance.

In addition to VOC regulation, the European Union's Biocide Product Directive (BPD) is another major environmental issue currently affecting biocide suppliers and, as a result, paint manufacturers. According to companies Coatings World spoke with, the BPD will have a major impact on the biocides industry. "The complexity and costs of data requirements will undoubtedly exclude market access to all but the most committed biocides companies," said Roger Johnstone, media relations manager, Avecia.

According to Mr. Johnstone, the BPD requirements are much more onerous than those in the U.S. and will become a major obstacle to the global marketing of biocides. "Very few new active substances will be brought to the market in the next few years and "comparative assessment will further discourage research," he said. "Many current actives will disappear from the market and approved products are likely to become more expensive."

In addition, he believes that many end-user processes and products will need to be modified or reformulated to include the biocides that remain on the market and there will be a higher risk of functional protection failure and hygiene decline in the future.

Though this paints a somewhat tough picture for the future of the biocides market, some suppliers believe the directive will provide some benefit to the industry. "Environmental testing, associated with the BPD, will add additional costs and provide new data about the environmental fate and toxicity of many biocides currently on the market," said Jerry Konst, North American marketing manager, preservatives at Dow. "This data will come at a significant monetary cost, but the resulting information should be very informative for the industry and users."

In addition to the number of environmental regulations involved with the biocides market and the coatings industry in general, there are other regulations that must be taken into account. ""Many people don't understand the regulatory environment that comes with making a microbicide," said Chuck Carncross, vice president coatings and plastics, Buckman Laboratories Inc.

When a biocide or microbicide is put into a paint to preserve it in the can or preserve the paint surface, there is no need to report or register anything with the government. However, when a coating containing a microbicide, claims to protect the substrate (such as a wood preservative) or claims it will kill bacteria or fungi in contact with the surface of the coating, then the coating must be registered with the EPA. In the first case you are saying the coating is protected from microbial attack. In the second case, you are claiming that the coating will protect something else from microbial attack, which by definition makes the coating a microbicide and must therefore be registered with the EPA. "When you make a paint that you claim is antibacterial, you are saying that this coating is a microbicide, and then it must be registered with the EPA," said Mr. Carncross. Companies in the past have received substantial fines for saying things are antimicrobial while not registering them with the government, Mr. Carncross continued.


Resistance
Governmental regulations are not the only obstacles that biocides formulators face. A serious issue concerning the medical profession today involves the overuse of antibiotics. This can prove dangerous because it can lead to the sensitization of microbes to the drugs, thus rendering them ineffective. The same issue concerns the biocides market for coatings, though not as severely.

"If proper concentrations of biocides are used, then development of resistance does not often occur," said Mr. Konst. "When a batch or several batches are made with too low a concentration of biocide (due to mistake in amount added or knowingly low level concentration added), then a population of organisms that is tolerant of a higher level of biocide can grow."

This means that products must be reformulated to combat these new organisms. "To prevent the development of tolerant organisms, coating formulators should make sure they always add the concentration of preservative that their biocide supplier recommends, based on challenge testing as well as maintaining 'good housekeeping,'" Mr. Konst added.

It is important to note, though, that bacteria resistance can be misdiagnosed. "It should also be noted that bacteria growing in biofilms on the walls of pipework may exist in a biocide-tolerant state because of the protection afforded by the slime layers," said Dr. Cornish. "Chunks of biofilm can break off at any time thereby inoculating your product with what appear to be biocide-resistant bacteria."


The Trouble with Pseudomonads
Even with good housekeeping, some bacteria are still difficult to formulate against. Nearly, all suppliers mentioned pseudomonads as a troublesome organism. "Pseudomonads are frequent spoilage organisms because they are ubiquitous, can grow quickly on a wide range of chemicals (surfactants, thickeners etc.) and readily form biofilm in pipework," said Dr. Cornish. "In general, all biocides have to be added at higher doses to kill pseudomonads because of the protection afforded by their protective outer membrane. But it is usually possible to provide good protection against these organisms provided that "best practice" biocide usage is followed."

Ms. Hoskins agreed. "Typically, the most widely isolated and associated bacteria in paints are "Pseudomonads," she said. "They are treatable like any other bacteria using standard preservatives. Selection of preservative will depend upon the potency of the actives.

"One should select a preservative that has the least minimum inhibitory concentration (MIC) against these bacteria and make sure the preservative package is compatible with the coating formulation," she continued. Balancing the two aspects is important along with maintaining good hygiene in the plant."

According to Dr. Cornish, some biocide formulators claim that combinations of actives are needed to combat pseudomonads. "We usually find that single actives are effective on their own but we do offer blended products, such as Proxel TN preservative, to deliver quick kill plus long term preservation where poor plant hygiene may be an issue," he said.

Dow also offers customized blends to meet specific needs, such as Dowcil QK-20 and Ucarcide 250, both of which are useful in cleaning up contaminated raw materials.

Another organism that is sometimes problematic is Gluconobacter, according to Dr. Cornish. Gluconobacter has emerged as a problem organism in some low pH adhesive systems, but Vantocil IB antimicrobial is an effective treatment option for this organism. It is also useful as a quick-kill aid, as it is very effective against pseudomonads and bacteria in general, he added.


Looking Ahead
The biocides market is not a simple one. In addition to the number of regulations for the coatings industry in general, there are others, specific to the market that must be addressed. The biocide market's growth is tied to the coatings market in general, which is still relatively slow, but suppliers are looking for things to improve. "With sustained economic recovery, we should see better economic performance for the second half of 2002 and into 2003," said Mr. Konst.

Still, the market is tough to predict. According to Mr. Carncross, "I think the market size will be understood when some of the applications that are more marketing related, such as kitchen and hand sanitizers, fall away" he said. "The coatings side that addresses real problems, such as wood preservation, the sick home issue, or hospital sanitation, will definitely stay around. It will be a bit of a growth market."

Biocides, Fungicides, Microbicides,
Mildewcides and Antimicrobials Suppliers
Here is how to contact the companies mentioned in this article.

Acima
Buchs, Switzerland
41-81-755-7600
Fax: 41-81-755-4659
Web: www.acima.com
  Dow
Midland, MI
(800) 447-4369
Web: www.dow.com
Avecia Protection and Hygiene
Wilmington, DE
Fax: (302) 477-8120
Web: www.avecia.com
  Troy Corporation
Florham Park, NJ
(973) 443-4200
Web: www.troycorp.com
Buckman Laboratories, Inc.
Memphis, TN
(800) BUCKMAN
Web: www.buckman.com
   


Should your company be here? To be included in our next feature on biocides contact:

Coatings World Magazine

Phone: (201) 825-2552
Fax:   (201) 825-0553
Website: www.coatingsworld.com
E-mail: coatingssales@rodpub.com




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