POLYSILOXANE COATINGS INNOVATIONSNorman R. Mowrer R&D Technical Manager Ameron International Performance Coatings & Finishes Group Brea, CA. Abstract: Organic modified polysiloxanes are generally recognized as the newest generic class of high performance protective coating. They have gained commercial acceptance over the last ten years and are now widely used in new construction, heavy duty OEM, marine and industrial maintenance painting. This paper provides an overview of the technology, describes the available types of polysiloxane modified organic coatings and their properties and briefly discusses some recent advances in the field. INTRODUCTION Inorganic silicon based polymers have been used as coating binders for more than 60 years. The first silicon based coating binders were the waterborne alkali silicates used in the formulation of heat-cured zinc rich primers in the 1940’s (1). Ambient-temperature, post- cure variants of this technology appeared in the 1950’s. Solvent based, zinc rich primers based on hydrolyzed ethyl silicate became available shortly thereafter. The development of silicone resins after World War II resulted in the first major commercial applications for silicone coatings; heat-cured, high temperature resistant paints for exhaust stacks, boilers, heat exchangers, mufflers, engines and aircraft components (2). Coating technologists have long sought to utilize the properties of inorganic silicon based polymers to improve the properties of organic coatings. Early attempts to combine inorganic silicon materials with organic resins by cold blending were limited by incompatibility of the two materials. The earliest examples of hybrid organic-inorganic silicone binders are the silicone alkyd copolymers. First developed in the 1950’s, these coatings overcame incompatibility problems by pre-reaction of silanol functional silicone resin carbinol functional organic resin. The resulting silicone alkyd copolymer was used to formulate industrial maintenance coatings (3) (4). These coatings are still in use today for the protection of U.S. Navy vessels, tanks, process equipment, rail cars and other steel structures and are the subject of various specifications including SSPC Paint 21, SSPC-PS 16.01 and MIL-PRF- 24635C. While these coatings improved weatherability, they also had all of the limitations associated with alkyd coatings. Other early examples of organic – inorganic silicon based coatings include silicone polyesters and silicone acrylics used in heat-cured coil coatings and high temperature resistant coatings. For many years, broader use of silicon based materials as coating binders was limited to the specialized coatings just mentioned, primarily because of poor film flexibility and toughness, incompatibility with organic polymers, the need for heat- curing and certain problems associated with film formation. A breakthrough was made with the publication of a patent in 1981 which described binders based on interpenetrating polymer networks (IPN) comprised of a polysiloxane network and an epoxy-amine network (5). Coatings based on this chemistry overcame the need for heat curing and provided good flexibility with improved solvent and acid resistance compared to conventional epoxy coatings. Cost, stability and intercoat adhesion problems limited commercial success. Significant further progress was made in the mid-1990’s with the commercialization of a patented epoxy siloxane hybrid (6). This coating combined the corrosion resistance of an epoxy with the weatherability of aliphatic polyurethane in one coating. When used in combination with inorganic zinc silicate primers, it allowed a single coat of the epoxy siloxane hybrid to replace one coat of epoxy and one coat of polyurethane and still provide the same level of resistance to weathering and corrosion. The combination of high performance and lower cost from elimination of the epoxy intermediate coat has led to wide spread use of the two-coat, zinc primer/epoxy siloxane topcoat system for protection of steel. Interest in these coatings has continued to grow and raw material suppliers, coatings manufacturers and universities have placed an increased emphasis on polysiloxane chemistry research over the last decade. As noted in a recent paper on the subject, polysiloxanes were the subject of 70 papers presented at three conferences during 2001-2003 and represented about 5% of all coatings patents issued during a 2-month period of 2002 (7). This research has led to rapid development of a variety of all-polysiloxane and organic modified polysiloxane hybrids and an expansion of their use in the protective coatings industry. With over 10 million square meters applied globally during the past ten years, polysiloxane coatings have gained market share compared to epoxy, polyurethane and other traditional organic coatings and are perhaps the fastest growing generic coating type. Of note, the number of coating manufacturers that supply polysiloxane coatings has nearly tripled in the last four years. The Buying Guide in the June 2000 JPCL listed nine manufacturers of polysiloxane coatings. Twenty-five suppliers are listed in the September 2004 JPCL Coatings Buyers Guide. The reasons for the rapid growth of polysiloxane coatings are clear. They offer improved performance properties and cost effectiveness, lower VOC content and improved health and safety features compared to traditional organic coatings. CHEMISTRY AND PROPERTIES Epoxy, polyurethane and other organic coatings degrade by thermal and photo- induced oxidation and are subject to chemical attack. This results in deterioration of coating properties such as color and gloss retention, flexibility, adhesion and corrosion resistance, which in turn reduces overall coating durability and service life. Polysiloxane coatings are largely inorganic in nature and are inherently more resistant to these degradation mechanisms for three principal reasons: 1. As shown in Figure 1, polysiloxanes are characterized by the presence of repeating Si-O groups in the polymer backbone. The bond strength of Si-O is 108 kcal/mole. Organic coatings contain C-C bonds, which have a bond strength of 83 kcal/mole. The higher energy required to cleave the Si-O bonds in polysiloxane coatings provides greater stability and superior resistance to weathering and thermal degradation. Two additional factors contribute synergistically to the stability of polysiloxane. Bulky organic substituents attached to the Si atom protect the Si-O-R bonds from hydrolysis through steric hindrance (9). At the same time, the positively charged silicon atoms polarize the organic substituents attached to them, thereby rendering the organic substituent less susceptible to attack (10). Figure 1.Idealized Polysiloxane Structure R O S i O R O S i O O S i R R R O O S i O R R R O S i O H R O S i O S i O R R S i R O S i R RO OH R = Si, H, Methyl, Phenyl, Other Alkyl, Aryl In addition to their excellent resistance to ultraviolet light, high temperature, oxidation and corrosion, polysiloxanes have a number of other properties that make them of interest as coating binders. • Silicone intermediates and silanes used in polysiloxane coatings have inherently low viscosities. Coatings with very high solids and low VOC (>90% volume solids with < 100 g/l VOC) can be formulated with the same application viscosity as much lower solids coatings. This allows compliance with current and all known future emissions regulations. 2. The siloxane bond has about 50% ionic character and is readily hydrolyzed, especially when catalyzed by an acid or base. Coating durability in weathering is thought to be due to the reversible nature of siloxane hydrolysis. Siloxanes in the presence of moisture are in equilibria that strongly favor condensation of silanols to siloxanes (8). The result is that a photon of absorbed high-energy radiation in the presence of moisture will hydrolyze siloxane bonds, but they reform spontaneously. In this way no permanent harm is done to the film. • Silanes used in formulating polysiloxane binders are also adhesion promoters and form tenacious bonds with both metal and cementitious substrates. • Unlike polyurethane, isocyanates are not used to crosslink polysiloxane binders. Health hazards associated with the use of isocyanates are eliminated. 3. The silicon in the polysiloxane polymer backbone is already approximately 50% to 75% oxidized, i.e., each Si is bonded to 2 to 3 oxygen atoms. Therefore, oxidative degradation that affects C-C bonds present in organic polymers cannot occur in the already oxidized Si-O polysiloxane polymer chain (9). Resistance of the polysiloxane to attack by atmospheric oxygen and oxidizing chemicals is improved. • Inorganic polysiloxanes are not combustible. Organic modified polysiloxane hybrids have better fire ratings and generate considerably less smoke and toxic fumes than organic coatings. • Polysiloxanes have excellent resistance to radiation. Since they also have good chemical resistance, nuclear decontamination properties are excellent. CURING REACTIONS Polysiloxane coatings are based on alkoxy or silanol functional silicone intermediates, which cure in the presence of atmospheric moisture by the condensation reactions as shown in Figure 2. Tin and other organometallic compounds are often used as catalysts to accelerate cure. Figure 2 Polysiloxane Hydrolytic Condensation Reactions Si OR + H2O + Si OH ROH ROH Si O Si + + Si OH RO Si Si OH Si HO + Si O Si + H2O Most commercially available organic – inorganic polysiloxane hybrids cure by reaction of an organo-functional alkoxysilane with both an organic resin and a silanol or alkoxy functional silicone intermediate. For example, an amino- functional alkoxysilane is used to cure epoxy siloxane and two-component acrylic siloxane hybrids. In the epoxy siloxane, the silane amine functionality reacts with an epoxy resin while the silanes alkoxysilyl group reacts with alkoxy or silanol functional silicone intermediate via hydrolytic polycondensation. In the acrylic siloxane, the silane amine functionality reacts with acrylate functionality via psuedo-Michael addition while its alkoxysilyl group reacts as previously described. Representative reactions are shown in Figure 3 and Figure 4. Single-component acrylic siloxane hybrids are based on pre-reaction of acrylic resins having hydroxyl, epoxy or other functionalities with alkoxy, isocyanate, amine or other organo- functional silanes. The resulting alkoxy functional acrylic resin cures in the presence of moisture via hydrolytic polycondensation. Figure 5 shows the representative reactions. Figure 3. Epoxy Siloxane Crosslinking Reactions R1O Si OR1 OR1 R2 N H H + R 3 O O AMINOSILANE EPOXY C H 2 C O H H R 3 R2 N H R1O Si OR1 OR1 TOGETHER WITH HYDROLYTIC CONDENSATION REACTIONS SHOWN IN FIG. 2 O Figure 4 Acrylic Siloxane Crosslinking Reactions R 1 O SI OR 1 OR 1 R 2 NH H R 1 O SI OR 1 OR 1 R 2 NH CH 2 CH 2 X R 4 + X R 4 X = ALTERNATIVE NUCLEOPHILES POSSIBLE TOGETHER WITH HYDROLYTIC CONDENSATION REACTIONS SHOWN IN FIGURE 2 Application temperature and relative humidity affect the relative rates of both the organic and inorganic polysiloxane curing reactions. The multiple reactions involved in the curing of organic – siloxane hybrid coatings result in rather complex polymer networks. Despite these complexities, polysiloxane coatings are application tolerant and have proven low temperature cure capability, even at low relative humidity. POLYSILOXANE COATING TYPES In general, fully crosslinked polysiloxanes are too brittle and do not have sufficient strength to be used as the sole binder for general-purpose coatings. Organic resins are incorporated to moderate these properties and tailor coating performance for specific applications. Successful coatings must be well formulated and depend on the selection of the appropriate type and amount of organic and inorganic polysiloxane constituents to achieve a balanced set of application and performance properties. Oxysilane and silicone resin precursors are selected for molecular weight, degree of crosslinking, reactivity type and amount as well as their film properties, cure speed and compatibility with organic resins. Organic resin precursors are chosen for their principal performance feature. For example, an aliphatic epoxy resin would be chosen for a coating requiring a combination of resistance to weathering and corrosion, an aromatic epoxy resin would be used in coatings that require excellent chemical resistance and an acrylic resin would be selected for use in a weatherable topcoat. Organic polysiloxane hybrid coatings vary from about 30 to 80% siloxane content to give optimum performance in terms of adhesion, mechanical properties and chemical, corrosion and weathering resistance. Lower levels of organic modification result in coatings the exhibit undesirable properties, e.g., low impact resistance and flexibility. Higher levels of organic modification detract from important polysiloxane characteristics like resistance to ultraviolet light and oxidation. The most prevalent, commercially available polysiloxane coatings are the epoxy siloxane and acrylic siloxane hybrids listed below. They are discussed in the sections that follow. • Weatherable, Corrosion Resistant Epoxy Siloxane • Chemical Resistant, Epoxy Siloxane • One-Component Acrylic Siloxane • Two-Component Acrylic Siloxane WEATHERABLE AND CORROSION RESISTANT EPOXY SILOXANE Epoxy coatings are the workhorses of the protective coatings industry because they are user friendly, have excellent corrosion resistance and adhesion to steel and provide good resistance to alkali and solvents. However, epoxy coatings have a major deficiency; poor exterior weathering. Conventional epoxy coatings exhibit chalking, color fade and lose most of their gloss after a year of exterior exposure. If retention of color and gloss is required, an aliphatic polyurethane topcoat must be used. The first epoxy siloxane hybrid was developed to improve the weathering resistance of epoxy without compromising corrosion or chemical resistance. Table 1 shows the properties of the epoxy siloxane hybrid coating. It has ultra high volume solids of 90% with a VOC of 1.0 lb/gal (120g/l). It can be applied by brush, roll or spray direct to blasted steel, prepared rusted steel and properly prepared, previously painted substrates. As shown in Figure 6, the accelerated weathering resistance of the epoxy siloxane hybrid is better than acrylic urethane. Table 1. Properties of Epoxy Siloxane Coating Volume Solids 90% VOC 1.0 lbs./gal. Mix Ratio by Vol 4 to 1 Applied Thickness 3-7 mils/coat Application Method Brush, Roll, Spray Substrate Prepared or Primed Steel, Concrete & Aged Coatings Pot Life, 70F 4 hours Dry to Touch, 70F 3 hours Dry Through, 70F 6 hours Recoat, Min. 4.5 hours Recoat, Max Extended An important feature of the epoxy siloxane hybrid is its excellent corrosion resistance and compatibility with zinc rich epoxy and inorganic zinc silicate (IOZ) primers. Table 2 offers a direct comparison of the following high performance coating systems: • 1-coat epoxy siloxane with 2-coat epoxy/urethane. • 2-coat IOZ/epoxy siloxane with 3-coat IOZ/epoxy urethane. The single coat of epoxy siloxane provides comparable resistance to corrosion and better resistance to QUV-B accelerated weathering than the 2-coat epoxy/urethane system. The 2-coat IOZ/epoxy siloxane system has equivalent or better resistance to corrosion and better resistance to QUV-B accelerated weathering than the 3-coat IOZ/epoxy/urethane system. Similar performance advantages are seen with zinc epoxy primer/epoxy siloxane topcoat systems compared to 2-coat zinc epoxy/urethane systems. Further evidence of the durability of epoxy siloxane is demonstrated by their excellent performance in various coating specifications and in tests conducted by independent laboratories Norsok Standard M-CR-501 This specification involves 6000 hours salt spray, 6000 hours condensation chamber and 4200 hours of cyclic exposure to salt spray and UV light. This test program in combination with its acceptance criteria is among the most severe performance tests in the protective coatings industry. A 2-coat system consisting of 2.5 mils inorganic zinc silicate primer and 5 mils of epoxy siloxane topcoat, applied on SA 2 abrasive blasted steel, has been tested successfully and satisfies the Norsok Standard Common Requirements as required by M-CR-501 Rev.2 (11). Further, a 2-coat system consisting of 3-mils of inorganic zinc and 5 mils of epoxy siloxane topcoat applied over UHP water-jet cleaned steel has also been qualified under the same specification (12). ISO 12944 A zinc epoxy primer/epoxy siloxane topcoat system has been tested in accordance with the ISO 12944 standard “Corrosion Protection of Steel by Protective Paint Systems” and passed the requirements for the C5M high marine corrosivity durability class (13). Cost Efficiency Epoxy siloxane hybrids have superior resistance to weathering and significantly better color and gloss retention compared to aliphatic acrylic urethanes. Based on comparative field data collected over the last 10 years, a 2-coat IOZ/epoxy siloxane coating system will provide a 30% improvement in service life compared to a conventional 3-coat, IOZ/epoxy/urethane coating system. As previously noted, the epoxy siloxane hybrid can be applied directly to inorganic zinc primer without pinholing, thus eliminating the epoxy tie- coat used in the traditional 3-coat IOZ/epoxy/urethane high performance coating system. Fewer coats minimize scaffolding, lower labor costs, reduce waste and result in increased productivity. The cost savings associated with longer service life and elimination of the epoxy mid-coat is significant. Coating system life projections based on the computer model described in NACE Paper 477 and current material, surface preparation and application labor costs have been used to calculate the capital expenditure, maintenance expenditure and total life costs of 2-coat IOZ/epoxy siloxane and 3-coat IOZ/epoxy/urethane coating systems. A total life cost savings of 12.9% was realized with the 2-coat inorganic zinc/epoxy siloxane coating system. Significant further cost savings are apparent when the reduction in man- hours are considered (14) (15). CHEMICAL RESISTANT EPOXY SILOXANE Epoxy coatings have good resistance to alkali and solvents but resistance to certain mineral and organic acids is limited. Siloxanes, on the other hand, have excellent resistance to concentrated mineral and organic acids. A chemical resistant epoxy siloxane hybrid coating, first introduced in 1997, combined the advantages of both polymers and provided resistance to a broad range of concentrated mineral and organic acids, alkali, oxidizing chemicals and aggressive solvents (16). Overall chemical resistance was better than methylene dianiline (MDA) cured epoxy and amine cured epoxy novolac coatings. Commercial success was limited by the coatings high crosslink density and associated shrinkage on aging, which led to stress cracking and disbondment from concrete at high coating thickness. An improved, elastomer modified epoxy siloxane hybrid was patented and commercialized in 2003 (17) (18). Elastomer modification of the epoxy siloxane polymer network has reduced shrinkage stress and eliminated cracking and concrete disbondment problems without compromising chemical resistance. The elastomer modified epoxy siloxane is a 3-component product consisting of resin, cure and silica aggregate and is designed as a self-leveling surfacer for application on concrete. Important characteristics of this coating are listed in Table 3. As shown in Table 4, the elastomer modified epoxy siloxane has excellent resistance to a broad range of concentrated mineral and organic acids, concentrated alkali, oxidizing chemicals and aggressive solvents. It is well suited for use in pulp and paper plants, chemical process industries, secondary containment applications and other industries where outstanding chemical resistance is required. Table 3. Elastomer Modified Epoxy Siloxane Surfacer Volume Solids 100% Applied Thickness 40-60 mils Application Method Squeegee, Roller Substrate Prepared, Primed Concrete Work Life @ 70F 2 hours Initial Setting Time 10 hours Time to Service • Light traffic • Chemical splash & spill 24 hours 72 hours ACRYLIC SILOXANE HYBRIDS Acrylics are the resins of choice to provide excellent resistance to weathering and are widely used in high performance acrylic latex paints and two component aliphatic polyurethane coatings. Appropriate acrylic resins can be used to modify polysiloxane binders to impart improved flexibility and recoatability while maintaining the superior weathering characteristics of the polysiloxane. The first acrylic siloxane hybrid was introduced in the late 1990’s (19). This product is a one-component coating specifically designed as an isocyanate- free replacement for two-component acrylic polyurethane. Advantages of the acrylic siloxane hybrid include excellent weathering, chalking and corrosion resistance combined with the ease of application of traditional one-component coatings at significantly lower VOC. Development of acrylic siloxane hybrid coatings has continued and a number of novel binders have been patented (20) (21) (22). Acrylic siloxane hybrids are now available from several suppliers. An epoxy acrylic siloxane hybrid is also commercially available. The products can be divided into two categories; 1- component coatings and 2-component coatings. Because the 1-component acrylic siloxane previously described was intended to compete with 2-component acrylic polyurethane at the required market price, it has low siloxane content and does not weather as well as the epoxy siloxane or 2-component acrylic siloxane hybrids. However, a second generation, higher solids, 1-component acrylic siloxane coating has been developed with higher siloxane content and improved weatherability. The versatility of 1-component acrylic siloxane chemistry also allowed this coating to be designed with improved flexibility. Long-term film integrity and durability should be improved. The properties of the first and second- generation, 1-component acrylic siloxane coatings are compared with commercially available 2-component acrylic siloxane and epoxy acrylic siloxane coatings in Table 5. The first generation, 1- component acrylic siloxane is not recommended for application over zinc rich epoxy but data is presented for completeness. QUV-B accelerated weathering of the coatings is shown in Figure 7. It is apparent after a review of this data that the second-generation, 1-component acrylic siloxane and 2-component acrylic siloxane have comparable resistance to corrosion and weathering while the 2- component epoxy acrylic siloxane has slightly lower performance. Advantages of the 1-component acrylic siloxane include unlimited pot life, better flexibility and the ease of application of traditional 1-pack coatings. The performance characteristics of acrylic siloxane coatings have been studied extensively by a number of suppliers. Based on this data and numerous case histories, it can be concluded that the high-solids, low VOC, non-isocyanate curing mechanism and combination of excellent corrosion resistance and superior weatherability of acrylic siloxane coatings make them an ideal, toxicologically more acceptable, cost effective alternative to polyurethane. It should be noted that acrylic siloxanes do not provide the same level of corrosion protection as the epoxy siloxane hybrid. Table 6 compares the corrosion resistance of coating systems prepared from a zinc rich epoxy primer topcoated with epoxy siloxane, 2-component acrylic siloxane and a 2-component acrylic urethane. The zinc epoxy/epoxy siloxane system out- performs the other coating systems. NEW ENGINEERED ORGANC-SILOXANE HYBRIDS The new siloxane chemistry gives coating technologists additional tools with which to design resin binders with improved properties. Siloxanes have been used advantageously in combination with vinyl’s, acetoacetate functional resins, urethanes, fluoropolymers and phenolics in coatings, adhesives and composites. Recent advances include development of fluorinated organic-siloxane hybrids and a fast-cure epoxy acrylic siloxane coating. Fluorinated Acrylic Siloxane and Fluorinated Epoxy Siloxane Hybrids The use of fluorinated polymers in highly weatherable topcoats is well known. For example, Kynar, one of several fluorinated polymer coatings on the market, is used to coat aluminum sheet metal used in building construction where the highest level of resistance to weathering is required. However, fluorinated polymer coatings generally have low solids content and high VOC and often require baking to achieve full cure. Fluorinated acrylic siloxane and fluorinated epoxy siloxane hybrids have been developed. These coatings combine improvements in resistance to ultraviolet light and weathering from proprietary fluorinated resins with high solids and low VOC of the acrylic and epoxy siloxane hybrids. Incorporation of fluorinated resin has been shown to improve the weathering resistance of both acrylic siloxane and epoxy siloxane hybrids. Comparative QUV-B accelerated weathering resistance is shown in Figure 8. Further testing of the fluorinated acrylic siloxane has shown greater than 95% gloss retention after 5-years exposure in Florida. Of note, weathering resistance of the fluorinated epoxy siloxane was improved without compromising the inherent corrosion resistance of epoxy siloxane. Fast-Cure Epoxy Acrylic Siloxane Hybrid Modification of organic and siloxane resins and their cure mechanisms has led to the development of an epoxy acrylic siloxane hybrid with very fast cure times. The coating has high solids and low VOC and exhibits weathering characteristics similar to the epoxy siloxane hybrid with 60-90% reduction in dry times. These properties were achieved without compromising flexibility. In fact, the percent elongation and impact resistance are actually better than the epoxy siloxane. Properties of the new coating are shown in Table 7. The fast- cure epoxy acrylic siloxane coating is ideal for product finishing, heavy-duty OEM and as a topcoat in so-called fast deployment coating systems. The technology is versatile. Higher solids, lower VOC versions are being developed for marine and industrial maintenance painting. Table 7. Fast-Cure Epoxy Acrylic Siloxane Components Resin, Cure Volume Solids 55% VOC 420g/l Application Method Spray Primers Epoxy, Alkyd, Other Pot Life, 70F 4 hours Comparative Properties Fast-Cure Epoxy Acrylic Siloxane (Epoxy Siloxane) Dry Times, minutes - Dust Free - Tack Free - Print Free 5 (75) 15 (145) 235 (40) Conical mandrel elongation 25 (15) % Impact Resistance - Direct - Reverse 6.0 (3.0) Joules 6.5 (2.0) Joules QUV-B Accelerated Weathering 60 o Gloss Retention - 4 weeks - 8 weeks 78 (75) % 68 (67) % SUMMARY In many ways, organic-siloxane hybrids are the most significant advance in ambient-cure protective coatings since polyurethane. The chemistry allows retention of desirable properties in existing systems while enhancing those areas needing improvement. Organic-siloxane coatings have been formulated with performance properties, durability and extended service life not previously obtainable with conventional organic coatings. Acrylic siloxane hybrid coatings have high solids, low VOC and cure at ambient temperatures without the use of isocyanate. Two-component and one component acrylic siloxane hybrids have comparable resistance to weathering; however, the one-component type has better flexibility, unlimited pot-life and offers ease of application. The superior weatherability and good corrosion resistance of acrylic siloxane hybrid coatings make them ideal as toxicologically more acceptable, cost effective alternatives to aliphatic polyurethane. Epoxy siloxane hybrids have ultra high solids, low VOC and cure at ambient temperature to provide coatings with an unsurpassed combination of resistance to weathering and corrosion. They provide the corrosion resistance of epoxy with weatherability better than aliphatic polyurethane in a single coating. Improved durability and elimination of epoxy primer and epoxy mid-coat in traditional multi-coat, high performance coating systems provides lower application and life-cycle costs for the protection of both small and large structures. CONCLUSION Polysiloxanes are the newest generic coating type. Recent advances have resulted in organic-siloxane hybrid coatings that offer significant improvements in ultraviolet light, heat, chemical, oxidation and corrosion resistance. Commercially available products offer improved performance properties and cost effectiveness, lower VOC content and improved health and safety features compared to traditional organic coatings and provide new options and real value for end users. References 1. H.H. Kline, “Inorganic Zinc Rich”, Generic Coating Types, Technology Publishing Co., p.166 (1996) 2. Hedlund, R.C., “Silicones”, Paint and Varnish Production, 44, No. 11, November 1954. 3. R. C. Hedlund, “Reactive Silicone Resins in Architectural Finishes”’ Paint Industry, (1959) 4. “Silicone-Organic Copolymer Resists Rigors of Weather”, Chemical Processing, November, (1962) 5. Foscante, et al., “Interpenetrating Polymer Network Comprising and Epoxy Polymer and Polysiloxane”, US Patent 4,250,074 (1981). 6. N. R. Mowrer, et al., “Epoxy Polysiloxane Coating and Flooring Compositions”, US Patent 5,618,860, (1997). 7. J.M Keijman, “Inorganic-Organic Hybrid Coatings in the Protective Coatings Industry”, Proceedings, SSPC 2002. 8. W.A. Finzel and H.L. Vincent,: Silicones in Coatongs” FSCT Monograph, p. 21, (1996) 9. L.H. Brown, “Silicones in Protective Coatings”, Treatise on Coatings, Vol 1, Part III, Film Forming Compositions, Marcel Dekker, p. 530 (1972). 10. W.A. Finzel and H.L Vincent, “Silicones in Coatings, FSCT Monograph, p 8, (1996). 11. “Testing of Dimetcote 9HS/PSX-700 in Accordance with Norsok M-CR- 501, System #1”, Corrosion Control Consultants & Labs, Inc., Report Number 190619071, November 1999 12. “Cyclic Testing of Amercoat 160HF/ PSX-700 In Accordance With Norsok M-CR-501, System #1”, National Institute of Technology, Norway, Report 27871KA02, September 1996. 13. “Testing Amercoat 68/PSX-700 System According to ISO/DIS 12944-6”, COT-BV Report Number LB97-188.RAP, May 1997. 14. G.H. Brevoort, “ A Review and Update of the Paint and Coatings Cost Selection Guide”, NACE Corrosion Conference (1993). 15. J.J. Snedden, “Petrochemical Plant Project – A Coatings Comparison”, Ameron UK Engineering Department Report, Revision 2, March 2000. 16. N.R. Mowrer, “The Use of Novel Epoxy Siloxane Polymers in Protective Coatings”, Epoxy Resin Formulators/ Society of the Plastic Industry, Proceedings, (1997). 17. H. Sakugawa, “Elastomer Modified Epoxy Siloxane Compositions”, U.S. Patent 6,639,025 (2003). 18. H. Sakugawa, “Chemical Resistant Elastomer Modified Epoxy Siloxane Surfacer”, Proceedings, SSPC 2003. 19. J.E. McCarthy, “ New Topcoat Technology For Maintenance Of Marine And Offshore Structures”, Proceedings, SSPC 1997. 20. S.A.M Kelly et al., “Coating Compositions”, PCT W/O 98/23691 (1998) 21. K.Yeats et al., “Ambient Temperature Coating Composition”, PCT patent WO 01/51575 (2001) 22. N. Schoonderwoerd et al., ”Coating Composition Comprising Polyacetoacetate, Crosslinker and Organosilane”, US Patent 6,203,607 (2001). Figure 5. One-Component Acrylic Siloxane Reactions C H H OH HO RO Si R R OR + Si R O C O Si OR H H R R OR R O C O Si OH H H R R O C O Si OH H H R R + ROH C O Si H H R R O Si OH R R Acrylic Polyol Alkoxy Functional Silane Alkoxy Silane Functional Acrylic Hydrolytic Polycondensation Crosslinked Acrylic Siloxane Acid / Base Water + H 2 O + Figure 6. Accelerated QUV-B Weathering of Epoxy Siloxane, Acrylic Siloxane And Other Generic Coating Types 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Exposure Time, Weeks 6 0 D e g r e e G l o s s Siloxane Acrylic Siloxane Epoxy Siloxane Acrylic Urethane Silicone Alkyd Alkyd Epoxy Figure 7. Accelerated QUV-B Weathering Of Acrylic Siloxane Coatings 20 30 40 50 60 70 80 90 100 0 3 6 9 Weeks Exposure S i x t y D e g r e e G l o s s 12 2nd Gen. 1-Pack Acrylic Siloxane 2-Pack Acrylic Siloxane 2-Pack Epoxy Acrylic Siloxane 1st Gen. 1-Pack Acrylic Siloxane Figure 8 QUV-B Accelerated Weathering of Fluorinated Siloxane Hybrids 40 50 60 70 80 90 100 0 3 6 9 12 15 Weeks Exposure S i x t y D e g r e e G l o s s Fluorinated Acrylic Siloxane Acrylic Siloxane Fluorinated Epoxy Siloxane Epoxy Siloxane Table 2. Comparison of Corrosion and Accelerated Weathering Resistance of Epoxy Siloxane vs. Epoxy/Urethane and IOZ/Epoxy Siloxane vs. IOZ/Epoxy/Urethane COATING SYSTEM EPS 1. EPOXY/ URETHANE IOZ 2. /EPS IOZ/EPOXY/ URETHANE Number of Coats 1 2 2 3 DFT, Mils 7 4 / 3 3 / 7 3 / 4 /3 Salt Spray; ASTM B117, 2000 Hours Blistering, ASTM D174 10 10 10 10 Rusting, ASTM D1654 10 10 10 10 Scribe Creep 8 7 10 8 Salt Spray, 5000 Hours Blistering -- -- 10 10 Rusting -- -- 10 10 Scribe Creep -- -- 6 2 Cleveland Humidity, ASTM D2247, 1500 Hours Blistering 10 10 10 10 Rusting 10 10 10 10 QUV – B Accelerated Weathering, ASTM G53, 60 Degree Gloss Initial 92 92 -- -- 1 week 91 88 -- -- 2 weeks 88 84 -- -- 4 weeks 78 70 -- -- 6 weeks 64 54 -- -- 8 weeks 58 46 -- -- 10 weeks 54 36 -- -- 12 weeks 52 21 -- -- 15 weeks 50 3 -- -- 1. EPS = Epoxy Polysiloxane 2. IOZ = Inorganic Zinc Table 4. Chemical Resistance of Elastomer Modified Epoxy Siloxane Surfacer Compressive Strength Before Immersion 10,875 psi Compressive Strength After Seven Day Immersion (psi) Acetic acid, 70% 10,020 Lime, sat 10,365 Acetic acid, conc. 10,555 Lye, NaOH, 25% 10,775 Acetone 10,855 Methylpyrollidone 10,955 Alum, 15% 10,710 MTBE 10,875 (NH 4 )OH, conc. 10,875 Methanol 10,735 Acetylaldehyde 10,890 Nitric acid, 50% 10,630 Ethanolamine 11,050 Nitric acid, 25% 10,350 Brake fluid 11,005 Potassium silicate 10,575 Citric acid, 25% 10,620 Petroleum ether 10,810 DMSO 10,745 Skydrol 10,530 Ethyl ether 10,715 NaOH, 50% 10,735 Ferric chloride, sat. 10,680 Na hypochlorite, 5% 10,745 Formaldehyde 10,675 Styrene 10,905 Tall oil fatty acid 10,695 Sulfuric acid, 98% 10,835 Gasoline 10,545 Tannic acid, sat. 10,605 Gasohol 10,565 Triethylamine 11,025 Hydrochloric acid, conc. 10,610 Vinyl acetate 11,165 H 2 O 2 , 30% 10,850 Xylene 10,715 Table 6. Comparative Corrosion Resistance Of Epoxy Siloxane, 2-Component Acrylic Siloxane and 2-Component Acrylic Urethane Coating Systems Topcoat Epoxy Siloxane 2-Component Acrylic Siloxane 2-Component Acrylic Urethane Primer Zinc Rich Epoxy Primer/Topcoat DFT, mils 3/5 3/5 3/5 Salt Fog, 2000 hrs. (ASTM B-117) - Unscribed Area, Blister - Unscribed Area, Rust - Scribed Area, Blister - Scribed Area, Creep 10 10 10 10 Few #8 10 Few #4 8 Few #8 9 Few#4 8 Cyclic Prohesion, 2000 hrs. (ASTM D5894) - Unscribed Area, Blister - Unscribed Area, Rust - Scribed Area, Blister - Scribed Area, Creep 10 10 10 10 10 10 10 10 10 10 10 10 Table 5. Comparisons of Acrylic Siloxane Coatings Coating Type 1 st Generation 1-Component Acrylic Siloxane 2 nd Generation 1-Component Acrylic Siloxane 2-Component Acrylic Siloxane 2-Component Epoxy Acrylic Siloxane Volume Solids, ISO3233 55% 79% 76% 75% VOC, EPA Method 24 384g/l 216g/l 172 g/l 216 g/l DFT/coat 2 mils 5 mils 5 mils 5 mils Pot Life, 70F Not Applicable Not Applicable 2 hours 8 hours Dry to Touch, 70F 2 hours 2 hours 3 hours 2 hours Dry Through, 70F 12 hours 9 hours 10 hours 18 hours Recoat, Min 6 hours 4 hours 4 hours 6 hours Recoat, Max Extended Extended Extended Extended Conical Mandrel Elongation - After 2 weeks at 70F - After 2 weeks at 70F plus 2 weeks at 140F 14.0% 3.0% 14.0% 9.0% 14.0% 3.0% 14.0% 3.0% Salt Fog Testing Over Zinc Rich Epoxy Primer – 2700 Hours (ASTM B-117) Primer/Topcoat DFT 3/2 mils 3/5 mils 3/5 mils 3/5 mils Unscribed Area - Blister - Rust Scribed Area - Blister - Creep Few # 2 None Few # 4 0.5 mm None None Few #4 0.5 mm None None Few #4 0.5 mm Few #8 None Med #2 0.8 mm Cleveland Humidity Testing Over Zinc Rich Epoxy (ASTM D-2247) 1000Hours - Blister - Rust 2000 Hours - Blister - Rust Few#2/ Med6, 8 None Med#2/Den#6 None Few#2/ Med6, 8 None Med#2/Den#6 None Few#2/Med#6,8 None Med#2/Den#4 None Med#2/Den#6 None Med#2/Den#6 None