VARIOUS VOC METHODS AND REQUIREMENTS AROUND THE GLOBE

Transcription

1 VARIOUS VOC METHODS AND REQUIREMENTS AROUND THE GLOBE Dr. Brij Mohal & Jerry Powers CHROMAFLO TECHNOLOGIES INTRODUCTION: Governing bodies around the globe share the same interest in air quality. One way that regulating groups decided to improve air quality is by lowering the volatile organic compounds (VOC) in architectural coatings. The simplest definition of volatile organic compounds (VOCs) comes from Canada: organic compounds with initial boiling point in the range of 50 to 250 C measured at standard pressure that can have an effect on air quality 1. The most complex definition(s) exist in the U.S. and there is not enough room (or desire) to present all of them within these pages. Imagine each local, state, and regional governing bodies with their own definitions and that is a fair start. U.S. formulators are now accustomed to this restriction and to measuring VOC in formulas since shortly after the initiation of the EPA. European formulators as well have dealt with VOC limits enforced the CEN, European Committee for Standardization. Besides governing bodies, market drivers like building construction in the U.S. and Europe require lower volatiles for LEED, Green, or EcoLabel distinction. The difference, of course, is that market driver VOC limits are voluntary. They are not required unless you want to participate in that market. Capitalizing in this market with Zero VOC claims carries risks as well. The FTC (Federal Trade Commission) has issued guidelines for labeling to prevent false advertising and confusion for the consumer 2. In the U.S., the FTC penalizes companies with confusing or false advertising on paint labels. The FTC released guidelines and an enforcement policy for advertising and labeling for manufacturers that claim to sell no VOC and low VOC products. Essentially, one cannot advertise a No VOC unless a result of 0 g/l is obtained. Also a company may not label or advertise trace VOC unless the VOC level is the same as background VOC levels 2. Companies must be able to prove that their paint products are as advertised on the label. If the label states VOC <10 g/l, for example, local, state, and federal entities require proof and the paint company is ultimately responsible for the product and how it is marketed. Companies in the past have been fined by the FTC for confusing or false advertising. 3 Companies that manufacture architectural paints in different countries typically sell products based on regional or continental requirements. As regional customers grow and become global customers, they typically desire the same products that they purchased previously be available in the other regions. Therefore, it makes sense for paint companies to become knowledgeable of global differences in VOC requirements and test methods. Paint companies assuming that low VOC in one country means low VOC in a different country are at risk of paying fines, but they also risk the loss of customers or potentially and entire market. VOC REGULATIONS: Table 1 displays countries or regions with their VOC limit for Architectural coatings and their test method for determination. 1

2 Table 1. Architectural Flats VOC Regulatory and Test Method by Country or Region 3,4,5 Country or Region VOC limit, g/l Test Method Governing Body United States 250 g/l less water Method 24 EPA, AIM Rule California (5 ASTM D counties) 50 g/l less water /Method 313 SCAQMD/ CARB Canada 30 g/l less water ASTM D /Method 313 Canada EPA Central America no regulation ASTM D / Green Seal ISO (GS-11) Jamaica South America Europe EcoLabel Africa 50 g/l less water no regulation regulated by nation 10 g/l ready to use no regulation ISO / ISO ISO / ISO China 120 g/l less water Similar to ISO / ISO PRC (SAC/TC5) Japan No regulation Eco Mark 1 g/l ISO series Japan Korea 40 g/l ready to use Similar to ISO AQP Hong Kong 50 g/l ready to use EPA Method 24 EPD Australia no mandatory regulation Australian Paint Approval Scheme 65 g/l ready to use Calculation or ASTM D3960 CE CE APAS D181 VOC TEST METHODS: Currently, there are several methods (EPA, ISO, and ASTM) to measure volatile organic components in Architectural low VOC colorants. Method 24 is still the most common method for determining VOC content in coatings 6. It measures VOC content indirectly by incorporating gravimetric analysis (ASTM ), moisture titration analysis (ASTM or 91 or ASTM , 90, or 96a), and density (ASTM D , 80, or 90). Unfortunately, Method 24 does not provide good precision with waterborne coatings nor does it perform well with low VOC coatings. When performing multiple methods to achieve a final result, the measurement percentage errors accumulate 7. More precise methods include Europe s ISO :2006. This is a method developed in the year 2000 by the International Standards Organization and is the responsibility of the CEN, (Comité Européen de Normalisation). This direct injection GC method measures VOC content within the range of 15% (150,000 ppm) to 0.1% (1,000 ppm) by mass (see Figure 1). VOC is calculated by the peak area measurement of an internal standard compared to the areas of the VOC peaks up to an endpoint that diethyl adipate provides. One of the challenges with this method is that it requires a priori knowledge of the sample. The analyst must know the 2

3 approximate VOC of the sample. Coating samples containing less than 1000 ppm in the coating or samples with greater than 15% VOC may provide erroneous results. Another European method practiced to measure VOC content is ISO 17895:2006. This method measures VOC content from 0.1% (1000 ppm) to 0.01% (100 ppm) by mass and is a headspace gas chromatography method (see Figure 2). The samples are prepared by 50% dilution with citrate buffer and measured against a standard addition calibration curve ranging from 100 ppm to 1000 ppm of a known solvent mix. A 15 mg sample of the buffer/coating mix is added to the bottom of a headspace vial. Issues with this method revolve around the small amount that technician must add to the headspace vials. The low mass allows for higher percentage relative error with each handling of the samples for the numerous trials. Also with a 5 point standard addition calibration plot, slight differences in peak area integration could lead to large differences in VOC content (see Figure 4). A seven solvent solution is used as the standard addition. The equation of the line renders the amount of VOC in the unspiked sample. ASTM D is currently being used by many U.S. companies to determine VOC content in many different types of coatings. ASTM international initially released this method in 2003 and reapproved it in This direct injection method is intended primarily for waterborne coatings with VOC content between 0.05% and 5% (see Figure 1), but has been used successfully with higher percentages. This method, however, also requires a priori knowledge of the sample in order for obtaining accurate results and has percentage error results as high as 30% based upon the coating type 8. The method recommends the use of the mass spectrometer for proper identification of samples. California s South Coast Air Quality Management District (SCAQMD) developed Method 313 as an improvement to ASTM D This direct injection method adds quality control, background, standard, and reference steps to the ASTM in order to increase the precision (see Figure 1). Also, Method 313 uses an increase in sample size to 2.5 grams, whereas ASTM D uses grams. Figure 1. Direct Injection GC methods (ISO , ASMT D6886, and Method 313) Direct Injection is a method in which liquid sample is directly injected onto the GC column. The liquid vaporizes at the inlet and vapors flow onto the column with carrier gas. 3

4 Figure 2. Headspace GC methods (ISO , ASMT D6886, and Method 313) The headspace method used in ISO incorporates a very small sample that is heated to allow vaporization into the open space in the vial (the headspace). A needle injects the septum of the vial and collects the vapors. The needle then injects the vapor onto the column of the GC. Both methods can use a split column to send the volatiles to a mass spectrometer detector (MS) and flame ionization detector (FID); see Figure 3. Figure 3. Gas Chromatograph, Mass Spectrometer, and Flame Ionization Apparatus Figure 3 illustrates the main components of GC VOC testing; the injection port (direct or headspace), the FID (flame ionization detector) for quantification, and MS (mass spectrometer) for identification of the volatiles. 4

5 Figure 4. Standard addition chart for ISO Headspace VOC Figure 4 above illustrates a 5 point standard addition plot. Slight changes in the peak areas for these additions could create differences in VOC results. Note in Figure 4 that run 2 and 3 are similar peak area even though the concentrations are different. Also, sample 4 has slightly more peak area although the concentration is less. As the slope changes, the equation of the line also changes. This changes the value x when y equals zero. This x is the calculated VOC concentration of the sample. It would be costly and time consuming for paint companies to pay third party laboratories to perform each of the above tests to determine compliance per country. It would be a resource and time burden for companies to perform all of these methods internally. Which method would be best to determine that the products are compliant for every VOC restriction globally? The bad news is none of the methods mentioned above are uniformly ideal for the varied coatings on the market today. One might think that ISO and ISO complement each other due to the range of percentage VOC. ISO measures VOC content from 15% to 0.1% while ISO measures VOC content from 0.1% to 0.01%. Testing results in Table 2 attest to the contrary. Table 2. VOC Colorant Results comparing ISO and ISO ISO nd lab VOC Sample g/l VOC wt% Wt% Results Red Colorant % 0.10% Orange Colorant % 0.10% Violet Colorant % 0.16% Green Colorant % 0.34% Black Colorant % 0.11% ISO nd lab VOC Sample g/l VOC wt% Wt% Results Red Colorant % 0.12% Orange Colorant % 0.05% Violet Colorant not run not run 0.81% Green Colorant % 0.49% Black Colorant % 0.09% 5

6 Some of the results (red, orange, and black) possess comparable results between methods. However, the violet and the green results are incongruous. The results of ISO for the Violet are five times the results of ISO Comparing the ASTM D method to the ISO method is just as confusing. The European method ISO is reported as in can or ready to use which means that water is included in the total VOC calculation. The SCAQMD D method is reported as regulatory, less water, or coating VOC which means that the calculation is based on the VOC after water is removed. Table 3 below displays a comparison of colorants tested using both methods. Table 3. Typical U.S. Colorant VOC comparison using ISO and ASTM D U.S. Colorants ISO VOC ASTM D VOC Typical Low VOC Line In Can, g/l Coating, g/l Lamp Black 1 7 Titanium White 1 14 Magenta 2 9 Raw Umber 1 14 Brown Oxide 1 15 Yellow Oxide 3 36 Organic Yellow 1 42 Phthalo Green 1 5 Red Oxide 1 1 Phthalo Blue 5 35 Medium Yellow 2 23 Organic Red 8 23 These U.S. colorants are formulated to meet SCAQMD limits of 50 g/l VOC. When meeting this requirement they are also <10 g/l VOC for the European EcoLabel market. Table 4 displays if the opposite is true. Table 4. Typical EU Colorant VOC comparison using ISO and ASTM D EU Colorants ISO VOC ASTM D VOC Typical Low VOC Line In Can, g/l Material, g/l Organic Red 5 53 White 5 68 Magenta 2 42 Raw Umber 6 63 Brown Oxide Yellow Oxide 5 57 Organic Yellow Phthalo Green 5 51 Red Oxide 6 61 Phthalo Blue 2 45 Med Yellow 2 41 Lamp Black

7 Although, ISO reveals that these colorants are compliant in Europe, they are not compliant in Canada or California based on ASTM D The ISO method failed at predicting compliance outside of Europe. ISO has further analysis of volatiles passed the diethyl adipate VOC endpoint. These peaks cover the SVOC with a methyl palmitate endpoint marker. The VOC plus SVOC (semi-volatile organic compounds) provide the TVOC (total volatile organic compounds) which may be closer to the ASTM D or Method 313 results. Figure 5 demonstrates the retention time between diethyl adipate and methyl palmitate in ISO Figure 5. ISO endpoint for VOC (diethyl adipate) and SVOC (methyl palmitate) Figure 5 reveals that diethyl adipate has a retention time of 9.58 minutes while methyl palmitate has and endpoint of minutes. The time between the markers dictates the SVOC content. Table 5 compares ISO VOC, SVOC and TVOC with ASTM D

8 Table 5. European EcoLabel Compliant Colorants VOC comparison using ISO and ASTM D Low VOC Line ISO In Can ASTM D EU EcoLabel Colorants VOC, g/l SVOC, g/l TVOC, g/l VOC, g/l Oxide yellow Lamp Black Phthalo Green Violet Permanent Yellow Organic Red Raw Umber Titanium white Oxide Red Med Yellow Magenta Phthalo Blue High Hide Red The results of ISO TVOC in Table 5 still do not quite match that of D6886. ISO reports results as In Can and ASTM D reports Regulatory VOC or less water VOC. This difference between the methods likely accounts for the variation in results. Results of ASTM D can be further improved upon by incorporating the larger sample size used in Method 313. The larger sample amount allows for possible detection of glycol peaks that would otherwise be lost in the method noise. All previous reporting of results in this paper have incorporated a large sample of 3 grams per colorant. Table 6 below displays the how drastically different results can be with an increased sample size. Table 6. A Typical Colorant Low VOC line comparing small and large sample sizes with ASTM D ASTM D gm sample 3 gm sample Typical U.S. Colorant Line VOC, g/l VOC, g/l Oxide Yellow Lamp Black Phthalo Green Violet Permanent Yellow Organic Red Raw Umber Titanium white Medium Yellow Magenta Phthalo Blue High Performance Red

9 CONCLUSIONS: When analyzing low VOC waterborne colorants, higher sample sizes improve peak resolution and detection. On coatings container labeling, SCAQMD only requires a calculated VOC listing. The samples in Table 6 indicate that the colorant company may be only calculating the VOC from the ingredients and not performing actual testing per ASTM D on each colorant. These colorants were advertised as <10 g/l on the label. This is an example of how different calculating VOC can be from VOC results per ASTM D testing. Calculating VOC from ingredient boiling points can be precarious. Ingredient boiling point may not relate to volatility temperature in a GC column! When selling into a known market with mandatory or voluntary regulations, it is always best to use the method dictated by the country. However, when formulating coatings or colorants, it is not feasible to test the VOC using every possible method that different countries use. When resources and time are limited, testing VOC on colorants or coatings intended for sale in varying international markets, ASTM D with a higher sample size appears to be the method of choice. In the majority of cases, this method appears to be the best GC direct injection method for prediction of compliance around the globe. BIBLIOGRAPHY 1. Definition of VOC, Health Canada, 2. Federal Trade Commission, Enforcement Policy Statement Regarding VOC-Free Claims for Architectural Coatings, Author Unknown, FTC Hits Paint Makers on Green Claims, Friday October 26, 2012, The Journal of Architectural Coatings, Durability and Design News, 4. Cogar, Jennifer; Puzzled by Global VOC and Emission Standards in Architectural Paints?, PCI, Eastman Chemical Co., Kingsport, TN, January 6, Lin, Xia; A Review of Compulsory Coatings Standards in China, Paint & Coatings Industry Magazine, Carpoly Chemical Group Co., Ltd. Guangdong, China, July 2, 2012, 6. APAS Document 181 Revision 10, Volatile Organic Compounds (VOC) Limits, , CISIRO 7. Brickweg, Lukas; Guillermo, Audrey; Jones, Dane; Wills, Max; Comprehensive VOC analysis method for architectural coatings. (Technology Today) Ibid 9. Jones, Dane; Wills, Max; Development of an Improved VOC Analysis for Architectural Coatings, California Air Resources Board Report and California EPA, July 31,