|Abstract or Summary
- Efficient usage of resin is of critical importance to industry in the manufacture of wood composite panels, because resin represents a significant proportion of product costs. However, resin efficiency is poorly defined in literature, making it difficult to compare manufacturing processes in quantifiable terms. Additionally, resin content in the product is often confused with resin input in the process. Developing a method to quantify resin efficiency would provide industry a quality control tool which help to minimize resin usage.
The ultimate objective of this project was to develop a set of tools and guidelines by which board manufacturers could assess resin usage in product, and make specific recommendations to improve resin efficiency in PB and MDF manufacture. To further this objective, the following tasks were identified:
First, determine a metric by which resin efficiency could be quantified. Second, survey industry to identify resin systems used in the manufacture of particleboard, as well as partners to collect samples of resinated furnishes and boards for analysis in this project. Third, identify a methodology by which resin content and distribution could be quantified in both resinated furnish and finished product. Finally, apply this methodology to collected samples, and correlate this resin content and distribution with board performance.
For this project, a quantifiable metric for resin efficiency was proposed as the product of two terms, a metric for board performance and a metric for resin usage. The metric for board performance was further defined for particleboard and fiberboard as the ratio of measured internal bond strength to the tensile strength perpendicular to the grain of the species of wood used, modified by the compaction ratio of the finished board.
A survey of industry was performed to identify resin systems used in the manufacture of particleboard and fiberboard and to obtain particleboard and fiberboard samples for analysis in this project. Sixty-three plants in the United States and Canada were contacted. However, only 19 plants completed the survey and only 3 provided usable sample sets (2 particleboard, 1 fiberboard) of furnish and furnished panels.
A method was developed by which actual resin coverage could be quantified in product without modification to the manufacture process. This method was applied to the 3 industry sample sets and 3 sets of laboratory samples that were prepared for comparison. All furnish samples were stained using Toluidine Blue O, which allows urea-formaldehyde and pMDI resins to be distinguished from wood under fluorescent illumination. A total of 450 micrographs (75 per sample) were taken of the industrial and laboratory samples. A semi-automatic image analysis program was written to quantify resin and wood coverage in each image obtained.
A review of prior literature led to the expectation that resin coverage would be correlated to actual resin content in the product. However, an analysis of the micrographs of the industry samples showed the industry samples to have lower resin coverage than expected. There was also no clear trend correlating resin coverage to resin content in the laboratory samples.
Based on the results of this work it was determined that the staining process of the methodology by which resin content and resin coverage were quantified was inadequate for calculating resin efficiency as proposed. Improvements to this methodology were identified and suggested for future work. The proposed definition of resin efficiency also shows a strong dependency on the board performance metric, which may be modified in future work. Resin efficiency and resin coverage were found to be greater in the laboratory samples than the industrial samples.
In conclusion, this paper proposes a new metric for resin efficiency which allows resin efficiency to be quantitatively compared for different manufacturing processes and parameters. The staining process used in this paper has been shown to be capable of detecting UF and pMDI resins and quantifying resin coverage without modification to the manufacturing process. These could be used by industry as a quality control tool to minimize resin usage and decrease product costs.