Isocyanate polymers may also be present in paints including:. Exposure to isocyanates can occur when aerosols, mists or powder paints containing isocyanates are released into the atmosphere during spraying or powder coating. Exposure to isocyanates can also occur during sanding of polyurethane paint that is not fully cured, as this activity can generate dusts containing un-reacted isocyanates.
Further, isocyanate-containing materials may release isocyanates into the atmosphere when heated. Exposure to isocyanates should be considered as high risk. SDS and labels should be checked to determine if the products you are using contain isocyanates. Workers who carry out surface preparation such as preparing old vehicles for spray painting could be exposed to lead when removing and sanding lead-based paints. Paint that contains lead can no longer be purchased in Australia and the use of lead-free paints will eventually eliminate exposure to lead and the associated risks.
The WHS Regulations contain specific requirements for working with lead including the identification of lead risk work and removing a worker from lead risk work in certain circumstances. You must maintain a register of the hazardous chemicals used, handled or stored at the workplace. The purpose of this register is to provide a source of information for both you, your workers and anyone else affected by a hazardous chemical, and to assist in the management of substances used or generated in spray painting or powder coating activities.
The register must list all the hazardous chemicals at your workplace and their current SDS, for example for any paints, coatings, solvents and thinners, fillers, strippers and cleaning products that are hazardous. The register must be readily accessible to anyone who is likely to be affected by a chemical and workers who are involved in using, handling or storing a chemical in the register.
Hazards have the potential to cause different types and severities of harm, ranging from minor discomfort to a serious injury or death. Many liquid paints and powder paints contain flammable substances. Spray painting vapours and mists, as well as powder paints used in powder coating can spread rapidly, particularly in an enclosed space, and create a potentially explosive atmosphere.
If the aerosol mist, vapour or powder paint is ignited, for example by static electricity, a lit cigarette or spark, it could result in an explosion that could destroy the building and kill or injure anyone nearby. Each of the outcomes involves a different type of harm with a range of severities and each has a different likelihood of occurrence. Under the WHS Regulations, a risk assessment is not mandatory for spray painting or powder coating, however it is required for specific situations, for example when working with asbestos.
In many circumstances a risk assessment will assist in determining the control measures that should be implemented. It will help to:. Once you have listed all the hazardous chemicals used in each stage of the spray painting or powder coating activity, you should review the information on the relevant labels and SDS to determine the nature and severity of the harm. Depending on the chemical, the severity of the harm could range from minor to major, for example from minor skin irritation to chronic lung disease or cancer.
Using information found in the label and SDS, spray painting and powder coating chemicals, mixtures or materials can be put into three hazard categories as provided in Table 3. Table 3 Hazard categories of spray painting or powder coating substances. High risk chemicals. A hazardous chemical should be considered as high risk if it is:. That is, they may cause hearing loss or exacerbate the effects of noise. Evaluating the use of these chemicals should be carried out in conjunction with the Code of Practice: Managing Noise and Preventing Hearing Loss at Work. Many chemicals that are used in spray painting including 2-part polyurethane paints containing isocyanates and toluene an ingredient in many oil-based paints , and in powder coating, such as triglycidyl isocyanurate, hydrofluoric acid and chromic acid are known to present significant health risks and should be assessed as high risk.
Medium risk chemicals. Medium risk hazardous chemicals include any substances that contain organic solvents that are not already assessed as high risk, or flammable liquids or combustible dusts. Low risk chemicals. Hazardous chemicals that are low risk include any other substances not already assessed as high or medium. The level of risk depends not only on the toxicity or flammability of the hazardous chemical but also on the nature of exposure including frequency of use, quantities used, effectiveness of existing controls such as exhaust or ventilation systems and the processes involved at the workplace.
For example, some spray painting processes may be more suitable than others when attempting to minimise the exposure of a hazardous chemical or the risk of fire see Table 4.
2012 Additives Handbook
Further guidance on managing risks associated with hazardous chemicals is available in the Code of Practice: Managing risks of hazardous chemicals in the workplace. Table 4 Characteristics of spray painting and powder coating activities. Conventional compressed air low pressure spray painting.
Airless high pressure spray painting. Air assisted airless spray painting. The nature of spray painting or powder coating activities varies according to the object being sprayed. When assessing risk, consider how:. Appendix A contains an example of a risk assessment that can be used as guidance when assessing the risks involved with spray painting or powder coating activities including associated activities.
Regulation 50 A person conducting a business or undertaking at a workplace must ensure that air monitoring is carried out to determine the airborne concentration of a substance or mixture at the workplace to which an exposure standard applies if:. The results of air monitoring must be recorded and kept for 30 years after the date the record is made.
A ir monitoring should be carried out by a person such as an occupational hygienist with skills to carry out the monitoring according to standards and to interpret the results. Results from air monitoring indicate how effective your control measures are, for example whether ventilation systems are operating as intended.
If monitoring identifies that the exposure standard is being exceeded, the control measures must be reviewed and any necessary changes made. Air monitoring cannot be used to determine a risk to health via skin contact of airborne chemicals. Some control measures are more effective than others. This ranking is known as the hierarchy of control. You must always aim to eliminate a hazard and associated risk first.
If this is not reasonably practicable, the risk must be minimised by using one or more of the following approaches:. If risk then remains, it must be minimised by implementing administrative controls , so far as is reasonably practicable, for example restricting access to spray painting areas or keeping the quantity of hazardous chemicals to minimum in the spray painting area. Any remaining risk must be minimised with suitable personal protective equipment PPE , for example breathing protection, gloves, aprons and protective eyewear.
Administrative control measures and PPE rely on human behaviour and supervision, and used on their own, tend to be least effective in minimising risks. A combination of these control measures may be required in order to adequately manage the risks with spray painting and powder coating. You should check that your chosen control measure does not introduce new hazards. Chapters 3, 4 and 5 of this Code provide information on control measures for spray painting and powder coating activities.
The control measures that are put in place to protect health and safety should be regularly reviewed to make sure they are effective.
If the control measure is not working effectively it must be revised to ensure it is effective in controlling the risk. Common review methods include workplace inspection, consultation, testing and analysing records and data. You can use the same methods as in the initial hazard identification step to check control measures. You should also consult your workers and their health and safety representatives and consider the following questions:. Are they openly raising health and safety concerns and reporting problems promptly? If problems are found, go back through the risk management steps, review your information and make further decisions about risk control.
Regulation A person conducting a business or undertaking must ensure health monitoring is provided to a worker carrying out work for the business or undertaking if:.
It involves the collection of data in order to evaluate the effects of exposure and to determine whether or not that the absorbed dose is within safe levels. Health monitoring, which may include biological monitoring, can assist in:. Biological monitoring is a way of assessing exposure to hazardous chemicals that may have been absorbed through the skin, ingested or inhaled, therefore, biological monitoring techniques should also be used. For example, workers exposed to lead may require biological monitoring to measure the level of lead in their blood.
Biological monitoring has the specific advantage of being able to take into account individual responses to particular hazardous chemicals. Individual responses are influenced by factors including size, fitness, personal hygiene, work practices, smoking and nutritional status. A person conducting a business or undertaking must ensure that where health monitoring must be provided to a worker, the type of heath monitoring referred to in the WHS Regulations is provided unless:.
Health monitoring is not an alternative to implementing control measures. If the results indicate that a worker is experiencing adverse health effects or signs of exposure to a hazardous chemical, the control measure must be reviewed and if necessary revised. Also provide the report to all other persons conducting a business or undertaking who have a duty to provide health monitoring for the worker. The WHS Regulations also contain specific requirements relating to health monitoring for lead.
If a worker is carrying out lead risk work, health monitoring must be provided to a worker before the worker first commences lead risk work and one month after the worker first commences lead risk work. Spray booths are enclosed or partially enclosed structures designed to prevent or reduce exposure to hazardous chemicals or vapours. A spray booth should be used when spray painting with a hazardous chemical, except when:. The airflow is either down draught, cross draught, end draught or any combination thereof.
These booths are usually down draught or cross draught and have open ends. Heavy and large objects, like cars, which are not easy to handle are often painted in the down draft spray painting booths. Spray booth ventilation control systems should operate a pre-purge cycle to remove any residue contaminants and also operate a minimum of a 5 minute post-purge period following spraying. Whenever possible, the spray s hould be directed towards the exhaust air outlet of a booth. For example, when spraying a tall object in a down-draught booth no spraying should be performed above shoulder height.
Extension poles or lift platforms should be used so that the operator can get above the object and spray towards the air exhaust outlet in the floor. The spray painter should never be positioned between the spray gun and the exhaust air outlet. See Figures 1 to 8 below for further guidance. Even with a ventilation system, there is still potential for flammable mists and vapours to accumulate inside the spray booth, which can increase the risk of fire and explosion.
Two common types of ventilation used in spray painting are:. They should be fitted with a particulate filtration system to filter overspray. Wherever possible, local exhaust ventilation should be used when a spray booth cannot be used. It may be necessary to use it in combination with other control measures. Information on local exhaust ventilation designed for hazardous areas is available in AS Electrical equipment for explosive atmospheres — protection by ventilation. It can be used to supplement local exhaust ventilation.
When using dilution ventilation:. Where it is not reasonably practicable to do the spray painting in a booth and it is carried out in a building or structure other than a confined space, the building or structure should be of open construction or a mechanical exhaust system should be used to prevent the build-up of flammable or toxic fumes.
When spray painting outside a spray booth or outdoors, a spray painting exclusion zone should be designated around the area where the spray painting is carried out. In general, the exclusion zone should, as far as is reasonably practicable, have at least six metres horizontal and two metres vertical clearance above and below the place where the paint is being applied. However, in deciding where to establish an exclusion zone and how big it should be, you should consider:. Greater vertical clearance may be needed when spray painting in stairwells and other areas which allow vertical movement of vapours.
A risk assessment will help determine if an exclusion zone is required for low risk processes such as painting with water-based paints. Once a spray paint exclusion zone is established, a number of procedures can be used to control risks including:. Only the spray gun and the cables connected to it should be in the exclusion zone. Put all other electrical equipment outside the zone or enclose it separately in a fire-resistant structure unless the equipment is suitably certified for use in an area in which an explosive atmosphere may be present.
Changing, washing and eating areas should be separated from the spray zone to reduce the risk of cross contamination and protect others. Persons other than the spray painter should not enter the exclusion zone during a spray painting operation unless equivalent PPE is worn. Figure 9 illustrates the control measures required when spraying outdoors.
Additional information about exclusion zones in different ventilation conditions is available in Appendix B. Figure 9 Example of an exclusion zone when conducting outdoor spray painting. You should ensure that the plant and equipment used in spray painting or powder coating activities is well maintained, operational and clean. This includes:. When undertaking maintenance of equipment, ensure that:. Cleaning of spray booths is made easier by covering exposed surfaces with non-flammable plastic film, which can be easily removed for cleaning or washing.
The use of absorbent material, for example paper, cardboards, wooden platforms, should be avoided. Frequent cleaning or replacement of the filter medium is required to prevent deposits blocking air flow. Never spray paint in the spray booth without an air filter medium, and.
Pressure from the gun and the paint pot should be released prior to cleaning. The gun should never be cleaned by covering the nozzle with a cloth or other material held in the hand, as this method of cleaning can result in paint injection injuries when used with airless spray guns. Section 19 A person conducting a business or undertaking must provide workers and other persons with information, training, instruction, and supervision necessary to protect all persons from risks to their health and safety arising from work carried out.
Regulation 39 A person conducting a business or undertaking must ensure that information, training and instruction provided to a worker is suitable and adequate having regard to:. The person must also ensure, so far as is reasonably practicable, that the information, training and instruction is provided in a way that is readily understandable to whom it is provided. Workers who are involved in spray painting or powder coating activities require relevant information, training, instruction or supervision to enable them to carry out their work safely.
For example, this must include information on. Training should be practical and where relevant include hands-on sessions, for example correctly setting up a spray zone or practising emergency procedures. Regulation 44 If personal protective equipment PPE is to be used at the workplace, the person conducting the business or undertaking must ensure that the equipment is selected to minimise risk to health and safety including by ensuring that the equipment is:.
A person conducting a business or undertaking who directs the carrying out of work must provide the worker with information, training and instruction in the proper use and wearing of personal protective equipment; and the storage and maintenance of personal protective equipment. A worker must, so far as reasonably able, wear the PPE in accordance with any information, training or reasonable instruction and must not intentionally misuse or damage the equipment.
In most cases PPE must be worn by workers when spray painting and powder coating to supplement higher levels of controls such as ventilation systems or administrative controls. Where PPE is worn by workers, it should not introduce other hazards to the worker, such as musculoskeletal injuries, thermal discomfort, or reduced visual and hearing capacity. Bacteria and their enzymes can degrade the organic components of paint — the polymer and its organic additives. One enzyme molecule can change hundreds of organic molecular structures and degrade them. The most obvious immediate result is a loss of viscosity.
This renders the product unstable and unusable. This is more of a problem for architectural coatings, which tend to be warehoused, shipped and then stored on shelves for longer periods than typical industrial coatings, which are usually consumed rapidly. Manufacturers and formulators need to be conscious of the fact that the dried paint film is subject to microbe attack from mold, mildew and algae — particularly in certain climates where temperature and humidity encourage microbe growth. For dried coating films, algae and fungi can cause discoloration, dirt entrapment, cracking, blistering and loss of adhesion.
A loss of adhesion is commonly associated with fungi growth as well as corrosion on certain substrates due to the moisture produced by fungi. Dependent on the climate, many exterior surfaces and roofs may be subject to algae growth, and not all fungicides are necessarily effective against algae. Certain areas of the world have already recognized this as a serious problem and one of concern for the preservation of exterior buildings.
The type of microorganism that can attack the coating depends on many factors including the presence of nutrients, the moisture content and the composition of both the substrate and the coating itself. Moisture is affected by the amount of rainfall, dew, humidity, temperature and time of year. Local environment conditions such as surfaces that are sheltered from wind and shaded areas also have an impact on microbial growth.
Nutrient sources include constituents of the coating, partially biodegradable material from other microorganisms or simply dirt. The substrate may affect the pH of the surface and make it suitable for microbe growth. Fungi favor acidic conditions such as those provide by wood and some species of wood are more susceptible to fungi attack than others.
Algae favor alkaline conditions such as those provided by masonry. For use in architectural coatings, it is important that the fungicidal material have a low solubility in water so that it is not readily leached out of the paint film. It should also not cause any weathering effect such as fading, chalking or discoloration. Some antimicrobial agents can cause fading in architectural coatings; therefore, it is always wise to expose the formulation to Weather-Ometer testing.
There are thousands of kinds of fungi and algae throughout the world. However, only a relatively few disfigure and deteriorate exterior paint films. In general, research on painted panels and structures from around the world indicates that two types of fungi are the dominant causative agents of disfigurement and degradation of modern exterior paint films. These fungi were identified as Alternaria sp. Aureobasidium pullulans is the fungus predominantly responsible for the development of mildew in exterior paints.
The Pseudomonas species attacks paints, joint compounds, roof coatings, exterior insulation and finishing systems and clear finishes in the can. There are many effective biocides available for use. It is important to understand the operation of these agents and the differences in their activity.
Some may be effective against certain bacteria in one concentration and effective against fungi in another concentration. Some biocides may be biocidal in certain concentrations and in other concentrations exhibit biostatic behavior. It is very important for the formulator to work with the supplier of these agents to understand their use and mode of action. Blends of biocides may often be used to enhance coating performance, as one biocide alone cannot always provide the desired results under demanding and varying climate conditions.
Some of the typical chemistries of these agents include: formaldehyde donors; ortho-phenylphenol OPPs ; isothiazolinone derivatives such as 2-n-octylisothiazolinone [OIT] ; guanides and biguanides such as PHMB or polyhexamethylene biguanide ; carbamates such as 3-iodopropynylbutyl carbamate [IPBC] and dithiocarbamates; copper or sodium or zinc pyrithione; benzimidazoles; n-haloalkylthio compounds; 1- 3-chloroallyl -3,5,7-tri-azaazonia-adamantane chloride; tetrachloroisophthalonitriles; cis[1- 3-chloroallyl -3,5,7-tri-azaazonia-adamantane] chloride and 2,2-dibromonitrilopropionamide DBNPA ; and quaternary ammonium compounds.
These are but a few examples of the many agents available to the formulator. Some biocides on the market today are two-for-one and eliminate the need for separate in-can preservatives and mildewcides. DCOIT 4,5-dichloron-octylisothiazolinone is an example of one such biocide, which controls bacteria that cause coatings to degrade in the can and prevent mildew growth after the films dry.
This particular biocide controls a wide range of microorganisms including fungi, algae and bacteria. EPA registered for use in coatings. It is formaldehyde-release free, does not contain heavy metal-based active ingredients and does not require ZnO for mildewcidal stability. The microbiological activity of 2,2-dibromonitrilopropionamide DBNPA was documented as a seed fungicide in and later as an antimicrobial agent.
The DBNPA molecule begins functioning as an antimicrobial agent immediately upon introduction into a system; the rate of this activity is not affected by pH, and antimicrobial control is usually achieved before complete degradation occurs. The combination of instantaneous antimicrobial activity and rapid chemical breakdown makes this a cost-effective and environmentally friendly biocide. It is used as a quick-kill biocide and short-term preservative in water-containing systems that require microbe control; it is ideal for the treatment of wastewater generated during the manufacture of paint.
The collection and reuse of all wash water used to rinse paint mixing vats has been emphasized as crucial to achieving environmentally responsible production. This wash water contains a high concentration of paint solids and is usually heavily contaminated with microorganisms; it must be decontaminated prior to its re-introduction into the paint production process. DBNPA is ideal for this type of application.
Mildewcide fungicide and algaecide testing has been very confusing for paint companies. The use of a single active ingredient may be sufficient to protect a coating against in-can spoilage or dry film defacement, but in many cases it may be advantageous to use a blend of the actives. For example, the combination of certain active ingredients can result in synergy whereby lesser amounts of each active are needed to bring about the same inhibitory effect as the use of either active alone. Thus blends of actives may allow manufacturers to protect a product at reduced levels, providing not only a potential cost benefit but also a product that is more environmentally friendly.
Even more important is for formulators to recognize the fact that even a minor change in a formulation may have a major effect on the biocide in that formulation. It is crucial with every change in formulation that the coating be tested for biocide efficacy. Some of the common factors that will decrease biocide efficiency are: pH, temperature of addition to the batch, nonionic surfactants, solubility, the presence of other formulation additives that deactivate the biocide, UV radiation and so forth.
The only way to determine the efficacy of a biocide in a coating is through testing. In testing various biocides in coatings there can be significant differences in performance of paint systems by exposure location. Since there can be such a wide variation in product performance by location, it is very dangerous to rely on data from one exposure site to assess how a national paint product might perform.
To truly assess the potential commercial performance of paint systems, they should be tested at a variety of locations across the country. Laboratory tests alone are not sufficient to assess how well a particular film preservative will perform in the field. For evaluating mildew resistance of interior coatings there is some uncertainty about which test method to follow for a realistic assessment of the coating.
Testing coatings in interior environments presents different challenges than for exterior coatings. There are several test methods and each claim to be the best for predicting in-service performance. Caution is urged in testing because evaluating coatings on non-porous substrates, like vinyl charts that resist wetting by moisture, makes it more difficult for fungi to proliferate on the coating surface.
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Therefore using these charts may over estimate the coating performance. Most interior paints are used on typical gypsum wall board with paper facing both sides. They absorb more moisture and retain it under humid conditions and thus are frequently susceptible to mold growth. So to evaluate interior paints, ASTM D with paper as a substrate or a variation of ASTM D with fungal inoculum deposited directly on the surface of a paper-based wall board may provide more realistic results. The traditional biocidal agents often are lost over time due to leaching or degradation of the film. Driven by the European Biocides Directive, many of these traditional biocides have come under greater scrutiny regarding their potential affect on the environment.
There is also concern regarding the ability of microorganisms to easily adapt to the additives used and build resistance over time. The result is a growing need for alternative solutions that provide sustainable antimicrobial protection while minimizing many of the potential issues related to the use of conventional additives. There is new, recently developed antimicrobial technology that offers unique ways to mitigate the effects of microbes on products. Unlike conventional active ingredients, the technology relies on antimicrobial polymers that either have inherent antimicrobial characteristics, or incorporate a conventional antimicrobial additive encapsulated or embedded into a polymer.
Since the active ingredient, or part of the molecule that is primarily responsible for the antimicrobial action, is attached to a polymer or uniformly embedded into the polymer at a nanoscopic level, these materials provide a more sustained and effective antimicrobial action over time. In addition to the antimicrobial action, these same materials can provide polymer-related attributes such as binding, adhesion, barrier and bonding properties that conventional antimicrobial additives cannot.
This multifunctional aspect may be of value where an ingredient is required to perform more than one function and thereby help in delivering a simpler and cost-effective solution. The intention for these new materials is thus not a direct replacement of the active ingredients used today but to provide additional benefits that cannot be provided in terms of durability, uniformity, consistency and greater functionality. Recent data shows that this polymeric route to antimicrobial functionality may be well suited for applications in textiles, nonwovens, medical products, hygiene and personal care products, building materials and a variety of formulated products including coatings and adhesives.
The requirements of the specific application determine which of the two approaches provides the best combination of antimicrobial and polymer properties. The inherent approach to antimicrobial functionality relies on the fact that the active site is part of the polymer and is tightly bound to the polymer backbone. The polymers are waterborne, easy to handle and environmentally favorable. Also, unlike conventional antimicrobial additives, these polymers are high-molecular weight materials and, therefore, less likely to be of concern regarding potential toxicology.
These polymers can be designed to provide additional attributes such as static control, permeability, barrier and strengthening properties, and can be tailored to suit a given application need. These materials would also be of interest in areas where a conventional AI active ingredient may not be desirable. Such applications could include hygiene products, medical devices and products or personal care products where the additional multifunctional aspects of this polymeric approach may be of greater value.
Unlike conventional antimicrobial additives that function by disrupting a biochemical pathway, these polymers function by breaching the integrity of the cell wall of the microbe. It is therefore believed that they are less likely to contribute to development of resistance in the targeted microbes.
A variety of active sites and polymer backbones can be designed to suit a given application. Since they are waterborne they can easily be deposited on surfaces by well-known processes such as coating, spraying, saturation or wet end deposition. The active ingredient AI approach involves the incorporation of active ingredients into a polymer whether it is inherently antimicrobial, as in the case above, or if the polymer is inert.
The AI is typically incorporated during the polymerization process in such a way that it is uniformly distributed into the polymer at a nanoscopic level. This embedding of the AI into the polymer matrix provides complete additive coverage of the surface in a more uniform and consistent manner thus increasing the longevity of the antimicrobial effect. In this way it is possible to get increased efficacy and sustainability from an AI while providing the benefits of a polymer in terms of ease of handling and durability.
It is also possible to use this approach to deliver a concentrated dose of the AI into a given formulation or application, coatings for example, where the AI is finely distributed into a polymeric carrier used only to deliver the AI. This is possible only because the method of incorporation allows high levels of the AI to be suspended into a polymer at a nanoscopic level without affecting the clarity of the polymer film.
Polymers containing the AI are waterborne and will have the performance properties associated with waterborne technology. Waterborne polymers are useful in applications where an additive is desirable, and would allow formulators to design sustainable solutions without many of the handling and durability issues related to the conventional additive approach. The choice of polymers and AI that can be used to provide a solution is varied and can be tailored to meet specific needs.
These new antimicrobial technologies that include inherently antimicrobial polymers as well as polymers that have encapsulated active ingredients provide a comprehensive approach to providing antimicrobial benefits across a wide variety of applications where sustainable antimicrobial functionality is needed, combined with the stated benefits of a polymeric offering.
These technologies present real value to customers interested in providing the multifunctional benefits derived from a polymer that has inherent or embedded antimicrobial characteristics. If applied to doorknobs or other surfaces where germs tend to accumulate, the new substance could help fight the spread of the flu. The new substance can kill influenza viruses before they infect new hosts. Influenza viruses exposed to the polymer coating were essentially wiped out.
The researchers observed a more than 10,fold drop in the number of viruses on surfaces coated with the substance. The polymers are also effective against many types of bacteria, including human pathogens Escherichia coli and Staphylococcus aureus , deadly strains of which are often resistant to antibiotics. For example, S. The new coating acts in a very different way from the many antibacterial products — such as soaps, sponges, cutting boards, pillows, mattresses and even toys — that are now on the market. Those products kill bacteria but not viruses and depend on a timed release of antibiotics, heavy metal ions or other biocides.
Once all of the biocide has been released, the antimicrobial activity disappears. With this type of polymeric architecture it is highly unlikely that bacteria will develop resistance because it would be difficult for bacteria to evolve a way to stop the polymer spikes from tearing holes in their membranes.
The MIT researchers are working with industrial and military partners such as Boeing and the Natick Army Research Center to develop the coatings for practical use. Once the polymer coating is applied to a surface, it should last about as long as a regular coat of paint. A growing problem in the world is that, for reasons of health and the environment, more biocides are being prohibited, and at the same time, bacteria are becoming more resistant. By using a double polymerization process, an anti-microbial binding agent is fabricated.
AM Coatings technology is part of the high-quality polymer: the acrylic resin. It is non-leaching, there is no negative environmental impact and no loss of effectiveness. Its effectiveness is evenly distributed in time and long lasting against bacteria, fungi, algae and other microorganisms. When a microbe or any micro-organism comes in contact with this surface, its cell wall is punctured like a balloon, and the microbe dies. Apart from being completely safe for man and environment, this mechanical action has another big advantage: microbes will not become resistant to this kind of control; a phenomenon which appears to become a growing problem, for instance with the notorious MRSA infection in hospitals.
This technology is not harmful to humans or animals; it can be applied everywhere and without special precautions. No special labeling or costly and time-consuming registration and admission procedures are required. Waterborne paints based on this technology possess enhanced low-odor and non-bleeding properties, and are just as green and sustainable as common, unmodified paints not containing additional antimicrobial components. Silver-based antimicrobials are compounds that contain silver whose beneficial properties make it useful as an antimicrobial agent.
The effectiveness of silver products is based on the slow and continuous leaching of superfine silver ions that interact with the metabolism of microorganisms. Silver ions can inhibit enzyme activity, especially those containing sulfur. In doing so, they have a major influence on the energy metabolism of these microorganisms.
Products containing silver demonstrate a broad level of antimicrobial effectiveness, however, significantly less activity is observed for attack of fungus when compared to bacteria. Examples of these antimicrobials are products where silver is embedded into base materials, such as special zeolites or glass. Furthermore, combinations of Ag and Zn used in zeolites may lead to synergistic effects. A silver-bearing zeolite antimicrobial compound, known as AgION, has been incorporated into polymer-based coatings to control the growth of harmful bacteria, mold and mildew.
These coatings may be applied to stainless or carbon steel products for use in appliance, food processing and HVAC applications. The active ingredients in the coating are the silver ions that are held within an aluminosilicate zeolite carrier particle. The silver ions exchange with other ions counter ions that may be present in nutrients or moisture and in this manner are transported to areas that support microbial growth. The antimicrobial properties of the silver ion have been recognized for a long time. The combination of silver or silver with benzisothiazoline gives a new and very effective preservative system.
By using this combination, the amount of sensitizing benzisothiazoline can be significantly reduced and, if an excess of benzisothiazoline is used, the well-known photosensitivity of silver compounds is reduced. This combination is a highly effective and safe new preservative system for coatings. Coatings enhanced with SmartSilver antimicrobial silver nanotechnology are effectively protected against a wide range of molds, fungi and bacteria, making it a highly efficient industrial antimicrobial. It can be incorporated into aqueous and polar organic solventborne coatings, powder coatings and injection-molded plastics.
SmartSilver additives do not impact the mechanical or flame-resistant properties of coatings, and are stable against UV light and high temperatures. The dispersible powders are highly concentrated, silver-containing antimicrobial additives made with proprietary stabilizers, and deliverable as powders or pre-dissolved dispersions. Typical use levels range from 0. The dispersed additives release silver ions when in contact with moisture, inhibiting the growth of microbes.
Ca OH 2 -based surface coatings, now available in a variety of pigmented colors, act to prevent infections — in particular influenza, sinus infections, pneumonia, allergic rhinitis, asthma and some indications are it is beneficial for anthrax as well. These one-application, antimicrobial-antibiotic surface coatings are effective against all classes of microbes including bacteria, viruses, fungus and algae. The coating combines calcium hydroxide as its active biocide with a special Bi-Neutralizing Agent BNA , a biopharmaceutical whose mode of action keeps the coating continuously working year after year.
Normally, hydrated lime is highly susceptible to atmospheric attack — carbon dioxide in the air quickly converts calcium hydroxide to calcium carbonate, reducing its alkalinity and rendering it ineffective. With BNA, calcium hydroxide is safely stabilized by this patented technology into a semi-permeable calcium hydroxide-encapsulated matrix system.
This specially engineered matrix system protects hydrated lime from atmospheric degradation, preserving its antimicrobial-biocidal potency long after the coating is applied. What is unique is its benign nature to humans and its lethal nature to microbes. The active ingredient is coming from a naturally occurring mineral and has been used for centuries as a safe and effective way to kill pathogens. The end-use product is waterborne, fast drying, virtually odorless and remarkably contains no VOCs.
It offers a widespread solution to the problems caused by the presence of the common microorganisms. Using an antimicrobial agent registered by the U. EPA, this multi-patented technology works by creating a surface coating that resists the growth of microbes on its surface for over six years. The growth of microorganisms on dry film not only affects the appearance of the coating discoloration , but may also compromise performance biodeterioration. Fungi can penetrate coatings, resulting in cracking, blistering and loss of adhesion, leading to decay or corrosion of the underlying substrate.
Algae colonies, which seem to grow more rapidly on porous substrates such as stucco, cement and brick, have the ability to occlude water. The freezing and thawing of this entrapped water may induce cracking or increase the permeation properties of the coating, leading to failure. Water may also encourage colonization by other microorganisms that, in turn, may cause biodeterioration. In order to be most effective, the biocide needs to be present at the coating interface, but this makes it susceptible to water leaching.
Controlling the release of the biocide through encapsulation ensures that a minimum concentration of biocide is always maintained at the surface interface, thereby extending the life of the coating. Additionally, controlled release reduces the amount of biocide that is released to the environment over a period of time.
Controlled release of IPBC through encapsulation renders the biocide more resistant to leaching. Outdoor exposure tests of paints containing encapsulated IPBC show enhanced dry-film protection. The amount of IPBC released depends on the intrinsic properties and composition of the paint. The controlled release mechanisms maintain a minimum biocide concentration in the coating interface over an extended period of time, preventing fungal growth.
This results in a longer coating shelf life given the same initial biocide concentration. Alternatively, lower biocide levels could be used to obtain a similar shelf life. There are many standard methods for determining the efficacy of a biocide for either in-can or dry film use. Chemical agent that prevents the undesirable sticking together or adhesion of painted surfaces under normal or specified conditions of pressure, temperature and humidity.
The brighteners are usually fluorescent dyes or pigments that absorb UV radiation and re-emit it as violet-blue light that gives yellowish-white coatings a brighter, whiter appearance. They are used to increase the luminance factor and to remove the yellow undertone of white or off-white materials. Small amounts of blue dyes are also used to achieve the same result. The optical brighteners or fluorescent whitening agents FWA are colorless to weakly colored organic compounds. In solution or applied to a substrate they impart bluish-white effects, have good light fastness and excellent heat resistance and chemical stability.
Agent that improves the resistance of a coating to increases in gloss or sheen due to rubbing or polishing. Lightweight spherical additives called hollow glass microspheres can be used for coatings formulations. These hollow glass microspheres offer scrub and burnish properties, in addition to viscosity control, thermal insulation and sound-dampening characteristics, and improved performance properties.
Spherical particles composed of styrene and acrylic polymers are also used for improving mar resistance as well as ceramic microspheres. High-molecular-weight micronized polyethylene or micronized polypropylene are used in architectural formulations for increased burnish resistance.
These waxes effectively replace silicas in both waterborne and solvent systems without settling. Polishing or burnishing a satin or flat clear coating occurs when silica is used in the formula to flatten the finish look. The problem with silica is that it orientates to the surface of the coating, and when the coating is rubbed, washed or marred, the top layer of silica is quickly worn away. With the use of nanoparticles, once again a synergetic effect is created between the silica and nano, giving a uniform distribution to the silica.
This gives the coating scratch resistance and no more polishing glossing up. Catalysts are additives that will increase the rate of a chemical reaction but are not consumed or changed in the reaction process. Catalysts have widely varying compositions that depend on the nature of the reaction being catalyzed. Many of the crosslinking reactions used to form durable films are accelerated by the use of catalysts. For example, melamine-crosslinked systems, polyurethanes and epoxies make use of catalysts.
Some systems use acids as catalysts: phosphoric, carboxylic or sulfonic acids [such as para-toluene sulfonic acid PTSA and dodecyl benzene sulfonic acid DDBSA ] can be used. Others make use of typical Lewis acid metal catalysts or Lewis tertiary amine base catalysts. Acid catalysts and blocked acid catalysts are used to accelerate the reaction between the crosslinking resin and the primary resin.
Good crosslinking is desirable so that the final cured film will show improved properties. By increasing the molecular weight of the crosslinked product, improvements are gained in chemical, humidity and detergent resistance, corrosion resistance, film flexibility and film hardness.
In general, the sulfonic and blocked sulfonic acids are strong acids, whereas the carboxylic and phosphates are considered weak acids. The formulator has to balance the properties of the catalyst with that of the crosslinking agent, the cure temperature and time, the pH of the system, and the desired final properties of the coating. This is not trivial and the raw-material suppliers have guidelines that can be followed.
A new class of blocked sulfonic acid catalysts, derived from aromatic sulfonic acids, has been developed that promotes the crosslinking of hydroxyl-functional polymers with amino-formaldehyde crosslinking agents such as hexamethoxymethyl melamine, especially in coil coatings. These catalysts are particularly effective in coil primer formulations containing calcium ion exchange anti-corrosive pigments. In addition, the unique deblocking profile of these catalysts provides the so-called snap cure at the desired peak metal temperature and within the specified time.
Products from this class of catalysts also are effective in topcoats where their cure response allows release of volatiles before cure, thereby preventing popping, while providing storage stability. DBTDL is efficient but, as with any catalyst, problems such as reactivity and hydrolysis of ester groups may occur.
The tertiary amines are effective for use with aromatic isocyanates. There are, however, some unique non-tin catalysts based on bismuth, aluminum and zirconium that are useful for these same reactions. The non-tin catalysts are environmentally more acceptable and offer advantages such as: faster cure rate, improved pot life, improved catalysis in cationic electrocoating and reduced hydrolysis of polyester resins.
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Catalyst deactivation can occur because of water, resins with high acid numbers, anions and pigments that are carrying water into the formulation. Oxidation reactions are of great interest in fine chemistry, at both the laboratory and industrial scale. There are numerous applications using the conversion of primary alcohols into aldehydes.
Two types of reactions could fit in with this scheme. Secondly, there are catalytic dehydrogenation reactions with catalysts such as copper chromite, Raney nickel, palladium acetate, etc. All these reactions do not fit in perfectly with the responsible care approach, which is now a priority in all chemical reactions. In effect, they present a number of drawbacks such as a high amount of metal waste, poor selectivity, safety issues in some cases, or harsh conditions. A new family of green catalysts has appeared in the last few years.
TEMPO, or 2,2,6,6-tetramethylpiperidinyloxy radical, is the most representative member of this family, and its efficiency in oxidation reactions is well documented. The oxidation of alcohols into aldehydes, ketones and carboxylic acids uses a catalytic amount of the nitroxyl radical and a stoichiometric amount of an oxidant such as sodium hypochlorite, m-chloroperbenzoic acid, sodium bromite, sodium chlorite, trichloroisocyanuric acid, bis acetoxy iodobenzene, n-chlorosuccinimide, or oxygen in combination with CuCl or RuCl 2 PPh 3 3. The nitroxyl radical is converted into an active species, which is the corresponding oxoammonium ion, and is then able to oxidize various substrates.
Nevertheless, the TEMPO or hydroxyl-TEMPO structures present several drawbacks such as poor thermal stability, strong volatility with a tendency to sublimation, high solubility in water with ensuing difficulties in treating the aqueous wastes, non-negligible toxicity, and a complex synthesis route involving several reaction steps. A new green nitroxyl catalyst called Oxynitrox S is on the market and was designed for oxidation reactions.
High activities and selectivities are achieved for different types of alcohols and its use can be extended to polyols or carbohydrates. It is classified as a green catalyst as it does not contain any metal. Additionally, it can efficiently replace classic metal catalysts such as copper chromite, chromium derivatives, catalysts based on ruthenium, molybdenum, silver, cerium, etc. It belongs to the family of nitroxyl radicals. It is generally used in homogeneous conditions, and the high molecular weight allows easy recovery of the end products by simple distillation.
The conditions that are generally followed for the use of Oxynitrox S correspond to a biphasic medium. The general procedure uses sodium hypochlorite as oxidant, Oxynitrox S as catalyst, dichloromethane, ethyl acetate or toluene as solvent, and sodium bromide as co-oxidant. The degree of oxidation of the final product can be controlled by the amount of sodium hypochlorite: when using 1 to 1. Caution is advised when using a catalyst in a powder coating formulation.
The point in using the catalyst is to increase cure speed during the bake. These gel particles cause defects in the finished film. Significant crosslinking in the extruder can also damage the equipment. Catalysts are used at low levels based on the binder — usually around 0. Many of the polyester manufacturers offer resins that contain catalysts and they provide information regarding the bake temperature.
Catalysts are also provided as masterbatches to improve distribution into the powder mixture.
Again the catalyst is specific to the binder type. A non-yellowing catalyst for uretdione crosslinked powder coatings has been developed that promotes the reaction of polyols and uretdione crosslinkers in powder coatings. This catalyst, K-KAT XK uretdione, is designed to improve on the two most common issues associated with using uretdione technology — high temperature curing and yellowing in the presence of common catalysts.
Physical properties of cured films in both clearcoats and pigmented systems have shown excellent chemical resistance, high gloss and good appearance. In addition, pigmented films have demonstrated little or no yellowing compared to uncatalyzed films under standard and overbake conditions. The acid scavenger prevents the carboxylic acid group on the hydroxyl functional polyester from inhibiting the catalyst activity. The product is a white, free-flowing powder that can be easily incorporated into uretdione-crosslinked powder coatings; it is also an effective catalyst for use in caprolactam-blocked polyisocyanate powder coatings.
The storage stability of the powder is excellent, and gloss and appearance of cured films is excellent. There are no adverse effects on corrosion, humidity and UV resistance by using this catalyst. Latent base catalysts are an attractive means of improving control over the curing process of adhesives.
At the same time they allow cure speed to be maintained and ensure excellent properties of the cured item. Thermally blocked amine catalysts are known, but require a fairly high de-blocking temperature to maintain sufficient stability of the uncured material, for example during storage and transport. The use of UV radiation to trigger the release of a base or acid catalyst is a worthwhile way of achieving optimum control over the application and the curing process. Numerous base-catalyzed crosslinking reactions require amines with well-balanced basicity and nucleophilicity properties.
The amidine structure provides an attractive alternative approach to photolatent structures: since the exceptionally high basicity of these compounds is attributed to the conjugative interaction of the two nitrogen atoms via the carbon-nitrogen double bond. Elimination of this double bond results in structures with isolated secondary and tertiary amine groups possessing a correspondingly lower basicity. Such amines can be used as latent precursors for the much stronger amidine base, provided the double bond can be created by a photo-initiated oxidation reaction using a suitable photo-removable group PRG.
Powder coating system optimized for efficient, repeatable powder application and fast, contamination-free color change. View our latest case studies and movies for our powder coating solutions. Keynote speaker: Jason Keeping, global process lead for ruggedized electronics on the Advanced Corporate Development team, Celestica.
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