New Developments in Alternative Wood Treatment LOU HONARY PROFESSOR AND DIRECTOR UNI-NABL CENTER JERALD D. HEISE MONSANTO FEDERICO TRIPODI,

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1 New Developments in Alternative Wood Treatment BY: LOU HONARY PROFESSOR AND DIRECTOR UNI-NABL CENTER JERALD D. HEISE MONSANTO AND FEDERICO TRIPODI, MONSANTO NOVEMBER 9, 2012 Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 1 of 9

2 New Developments in Alternative Wood Treatment Background Since 1991, the University of Northern Iowa s National Ag-Based Lubricants Center has been engaged in research and development of alternative uses of soybean oil and other renewable oils. The primary area of focus for the Center has been industrial lubricants and greases. Currently over 50 commercial biobased lubricants and greases including a line of biobased rail curve greases owes their commercial use to the research effort of the UNI-NABL Center. In early 2000, the Center staff in cooperation with an Iowa company that manufactured wooden bearings began to impregnate wood bearing with oxidized soybean oils. This would help the wood to use the oil for lubricating the rotating shafts while on the outside the polymerized oil would form a seal thus preventing the oil leakage. The concept was later expanded and patented for treating railroad ties, utility boards and highway sign posts or decking boards. Combination of the prepared soybean oil with copper naphthenate, with borate, and with various other additives were tested and presented at two RTA annual meetings. The one persisting problem with all such experiments remained to be the slow curing of soybean oil which resulted in a tacky outer surface with associated problems. This year, UNI-NABL conducted tests on, a new soybean oil trait being developed by Monsanto, originally designed as a food ingredient due to a high level of Omega-3 content. This new oil is highly touted for its health benefits, due to the conversion in the human body to Eicosapentanoic Acid (EPA), normally present in fish oil. Studies conducted at Monsanto 1 previously demonstrated that this oil has potential in industrial applications as well. Recently, this oil has shown to offer revolutionary performance for wood treatments and any application that requires rapid drying. Under a testing contract, the UNI-NABL researchers began to test the new Monsanto soybean oil in wood treating applications and the results have shown that this is breakthrough technology. This new soybean oil is called stearidonate or SDA. The attributes demonstrated at UNI-NABL like faster drying and increased polymerization rate are a function of the content and type of polyunsaturated fatty acids in this oil. This new soybean oil has higher levels of fatty acids with 3 double bonds (18:3). The 18:3 fatty acids present are alpha linolenic (ω 3) and gamma linolenic (ω 6). In addition, this new oil contains about 20% stearidonic acid, a fatty acid with 4 double bonds. While the conventional soybean oil has around 8% alpha linolenic acid, SDA oil has upwards of 12% linolenic acid. Additionally, the oil contains about 3 4% gamma linolenic acid. This oil also contains very high levels of stearidonic acid, around 20%. The total number of double bonds as measured by the iodine value (IV) can be a very good indicator of an oils stability or lack thereof. Commodity soybean oil has an IV around 130 but, SDA oil has and IV around 180 mainly due to the increased levels of 18:3 and 18:4 fatty acids. In general, as the iodine value increases, stability decreases. Oils with higher IV s are more prone to oxidation and polymerization. Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 2 of 9

3 For reference, oleic acid with one double bond has a relative oxidation rate of 1,linoleic acid with two double bonds has a relative oxidation rate around 50 and and fatty acids withthree double bonds have relative oxidation rates around Arachidonic acid (20:4) which contains four double bonds has a relative oxidation rate of This should be on par with the relative oxidation rate expected from SDA (18:4). Starting with 18:2 which contains 1 bis-allylic site, the relative oxidation rates for other fatty acids are surprisingly linear to the number of bis-allylic sites found in these molecules, 18:3 and 18:4 contains 2 and 3 bis-allylic sites, respectively. As a result, when properly exposed to oxygen, the SDA oil offers rapid drying performance that is better than other drying oils like linseed oil. Figure 1 presents four fatty acids, the first three of which are commonly found at different levels in most vegetable oils; with the fourth one being stearidonic acid (SDA). With a high percentage of linolenic and stearidonic acids in SDA soybean oil, thin films of the oil on surfaces are quickly oxidized to a hardened polymer film. Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 3 of 9

4 Stearic Acid (0 double bonds very stable) F a t t y A c i d & S t a b i l i y Oleic Acid (1 double bonds) Linoleic (2 double bonds) Linolenic (3 double bonds) Stearidonic Acid (4 double bonds) Figure 1: Fatty acids commonly found in vegetable oils and stearidonic acid The UNI-NABL Center staff has replicated its previous tests using the SDA soybean oil in several wood samples and this paper provides an overview of the project. Additional testing of the oil in conjunction with other preservatives is currently under way and will be reported at the future RTA meetings. Biobased Wood Preservatives The idea of using vegetable oils or other materials to seal the exterior of wood products is not new. Wood treating technology is mature and the current products on the market provide for effective and proven wood preservation. There is an interest, however, to explore the use of alternative carriers of preservatives in order to overcome the shortcoming of some of the existing products. Current products including creosote, copper naphthenate, Chromate Copper Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 4 of 9

The biobased carrier, regardless of its source, however, must prove to perform effectively in preserving the wood while offering attractive return on investment.

5 Arsenic (CCA) for example may have issues such as leaching, migration, and health or environmental concerns. Other products like borate might benefit from the sealing properties of oil based preservatives. The biobased carrier, regardless of its source, however, must prove to perform effectively in preserving the wood while offering attractive return on investment. The SDA oil has shown to present two unique properties that are not common with other vegetable oils. First, due to its fatty acid composition, it is fast curing thus showing potential for use in a wide variety of applications. Second, due to a yet to be determined synergy, at first it shows a higher level of resistance to oxidation when exposed to heat and oxygen like in the blowing process; but once the resistance is overcome, it rapidly oxidizes and almost fully polymerizes. This latter property could potentially increase the usability of this oil for wood treating. Because, the oil would maintain its stability and not gum up the equipment while in storage or in the treating chamber. But once a thin film of the oil on the surface of the wood is exposed to air, it quickly oxidizes to form a protective polymer film. To date, the SDA oil has shown to work effectively alone or mixed with the common preservatives. Due to its renewability, the SDA oil shows promise for mixing with existing effective products such as creosote to both help in creating a water barrier and preventing migration within the wood, and to improve the friendliness of the mixture. Experimental Work Previously, a combination of oxidized soybean oil, copper naphthenate, and anti-fungal additives were mixed along with some thinning fluids to be used for treating wood samples. Figure 2a and 2b show the treating chambers used for this project. 2a 2b Figures 2a and 2b: Treating chambers used for this project The treated wood showed fast curing within 24 hours. When a treated sample was placed in an oven at 65 C for 48 hours the outer layer of the oil formed a visible transparent coating. The experiment Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 5 of 9

Grams included testing the oil at various temperatures and pressure to determine depth of penetration and the amount of oil absorption by each sample.

Table 2 shows the results of treating at the temperatures and pressures as indicated. Some wood samples were incised to determine changes in the amount of oil absorption.

6 Grams included testing the oil at various temperatures and pressure to determine depth of penetration and the amount of oil absorption by each sample. Figure 3 shows the samples treated wood with 3a being 6 in length kiln dried 3 by 4 softwood and 3b showing a 6 sample of a manufactured wood. Table 2 shows the results of treating at the temperatures and pressures as indicated. Some wood samples were incised to determine changes in the amount of oil absorption. 3a 3b Figure 3a and 3b sample treated wood and manufactured wood Absroption of SDA oil at varied temperature and pressures Mass before test Mass after test 24 hours mass 1 week mass 2week mass absorbed oil mass Pressure and temperature settings Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 6 of 9

4a 4b Figure 4a and 4b: a section of a treated wood and the presence of polymer 5a 5b Figure

6b, and 6c show samples of the wood that were treated with a mixture of copper naphthenate

Similarly, figures 7a, 7b, and 7c presents images of a wood sample that was treated with the

When scraped off with a sharp object, enlarged view showed a clear layer of polymer lifted

7 4a 4b Figure 4a and 4b: a section of a treated wood and the presence of polymer 5a 5b Figure 5a and 5b: a section of a treated wood and the presence of polymer The following figures 6a, 6b, and 6c show samples of the wood that were treated with a mixture of copper naphthenate and SDA soybean oil and then exposed to 65 C for 48 hours in an incubator. Similarly, figures 7a, 7b, and 7c presents images of a wood sample that was treated with the SDA oil and then exposed to 65 C for 48 hours. These samples show a heavy coating of polymer. When scraped off with a sharp object, enlarged view showed a clear layer of polymer lifted off (Figure 8). Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 7 of 9

8 Figures 6a, 6b, and 6c: samples treated with SDA oil and copper naphthenate Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 8 of 9

9 Figure 7a, 7b, and 7xc: Manufactured wood treated with SDA soybean oil and exposed to 65 C for 48 hours Figure 8: Scraped off layer of polymer on a treated wood sample Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 9 of 9

10 Conclusions The research and development activities for this project started in early 2000 but were disrupted in 2007 due to an unrelated fire in a production facility. A new variety of soybean oil with great performance in wood treating has provided an impetus for this product to be retested for commercialization. The use of soybean oil and a US grown crop as a carrier for preservatives in wood treating has potential for offering a sustainable and competitive alternative to be used in conjunction with current preservatives. The rapid oxidation of the SDA oil and the formation of a polymer coating on the surface of the wood can provide a natural and relatively pliable water barrier. Previous tests included the use of soybean oil in combination with copper naphthenate and various antimold and anti-fungi materials. These railroad ties and highway sign posts have been in the field for nearly seven years. The product show great potential for mixing with creosote to help reduce migration improve the overall performance the mixture. The research group is seeking collaborators to test the new SDA soybean oil in conjunction with known preservatives. Further test results will be disseminated through RTA. Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 10 of 9

11 REFERENCES 1. Morgenstern, David A.; Makadia, Vallabh; Heise, Jerald D.; Calabotta, Beth J.; Estep, JoAnn; Nissing, Nicholas J. Use of Oils with High Concentrations of Polyunsaturated Fatty Acids in Plastics and Surface Coatings. U.S. Patent US 2009/ A1, Lipid Oxidation, Edwin N. Frankel, Publisher: The Oily Press, 2005, Second Addition Honary, L. Heise, J. and Tripodi, F. New Developments in Alternative Wood Treatment Page 11 of 9

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