Updated June 25, 2018:
Executive Summary
The desire to make environmental friendly, non-toxic and lower-cost wood based products has led to an interest in developing adhesives that can replace phenol and formaldehyde adhesives. Soybean oil is the most readily available and one of the low cost vegetable oils in the world today. For many years soybean oil has been a major ingredient in making alkyd resins, which are dissolved in carrier solvents to make oil–based paints and now it is considered as a building block for adhesives for wood composites. Commonly used adhesives include phenol formaldehyde (PF), urea formaldehyde (UF), melamine urea formaldehyde (MUF) and Methyl diphenyl diisocyanate (MDI). Lately formaldehyde resins are also under severe scrutiny due to formaldehyde emission and chemicals known to cause allergies or skin and eye irritation and EPA has described formaldehyde as a cancer causing carcinogenic compound. Our research team has identified that soybean oil based ESS (epoxidized sucrose soyate) can be successfully used to replace formaldehyde resin without any major technological investment. One barrier for commercial acceptance is higher curing time of ESS resin than the traditional resins. Therefore this project is focused on understanding and identifying techniques that will reduce the curing time of ESS resin so it is acceptable to industry.
To meet the project objective the team set two tasks 1) Evaluate the curing kinetics of ESS resin using most effective cross linker and catalysts blends and optimize/reduce the curing time so it matches with industry standards and 2) Manufacture particleboards with ESS resin blends under lowest curing time and test their physical and mechanical properties. The team identified two novel cross-linkers (MHHPA and MTHPA) and three catalysts (AC-8, BV-CAT7 and BV-CAT7FC) could help in curing time reduction. The materials were supplied by Broadview Company, NJ. After initial testing three formulations were identified for manufacturing lab scale particleboards. The particleboards were manufactured using a hot press and tested per ASTM D1037 standard.
The results showed that crosslinker MHHPA and catalyst BV-CAT7FC can reduce the curing time of particleboards from 30 min to 5 or 10 min when pressed under 175 or 190°C. Further ESS resin can be easily blended with commercial adhesives up to 50% without a significant loss in strength and durability properties. The low curing temperature of this resin will help manufacturers conserve energy as well as a safe and green alternative to replace formaldehyde adhesives.
The outcomes/results of this research are expected to benefit North Dakota soybean farmers as it will diversify soy based products with increased demand for soybean oil the principal component of the ESS adhesive. The market will have a formaldehyde free adhesive for particleboards. It will also help North Dakota economy by attracting investors and other soy processing industries. This work supports and advances the mission and vision set by North Dakota Soybean Council.
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