Prediction of the properties of board by using a spectroscopic m

Details Prediction of the properties of board by using a spectroscopic m Prediction of the properties of board by using a spectroscopic m

1997-12-31

1999-10-12

Hannaher, Constantine

Radiant energy

Invisible radiant energy responsive electric signalling

Infrared responsive

25033907, 25033911, G01N 2117

Patent

active

059658886

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This present invention is directed to a method for qualitative and quantitative determination of various parameters reflecting the properties of particleboard and other wood based panels, more particularly to a spectroscopic method combined with multivariate calibration, performed on the raw wood material flow into a plant comprising a process for production of wood based panels, especially on the dried surface and core particles, for the instantaneous and continuous analysis of the various parameters reflecting the quality of the wood based panel and with the knowledge thereof, optionally determine the process variables.
The invention especially relates to the use of NIR (near-infrared) technique combined with multivariate calibration as a tool for prediction of the properties of particleboard and other wood based panels.
It also relates to method for determination of parameters of a wood based panel by analyzing the wood based panel itself by means of a spectrometric method in combination with multivariate analysis.


BACKGROUND OF THE INVENTION

Particleboard can be produced from dry, fine wood particles that are mixed with binders and formed into a mat, which is then pressed together under high temperature and pressure into a densified board.
Wood raw material of almost any type of species may be used. However, the properties of the finished board, such as, for example, density, glueability etc are dependent upon the properties of the wood.
Sawdust, shavings, chips and shavings from round wood, in this specification and claims, referred to as "particles", are used as wood raw material. Flaking of the round wood takes place in drum flakers, while chips are processed in knifering flakers.
Subsequent to disintegration all wood material is dried down to 2-4% moisture in high capacity dryers. After the drying process the wood particles are screened to the preferred size. Rejected material passes through hammer mills and is fed back to the screening system.
Both the form of the flakes/sawdust and their size distribution are of importance for the board properties.
The most commonly used binder for particleboard and medium density fibre boards (MDF), is urea-formaldehyde resin (UF), but also melamine-urea resin (MUF), phenol resin (PF) and isocyanate resin (MDI) are used to some extent, especially for production of weather resistant board.
Resin, water, hardener and wax emulsion are automatically dosed on weight base. Dosages of the chemicals are calculated on the dry substance in percent of dry wood material. The amounts of binder added varies depending upon the resin type and the quality of board desired.
The dosage of UF resin is normally between 7-10%, MUF-resin between 11-13%, PF resin between 6-8% and MDI resin between 2-5%. The comparatively low dosages of PF and MDI resins reflect the superior binding ability of these resins.
A normal particleboard consists of about 6% moisture, 9% binding agent and other chemicals and 85% wood. In spite of the fact that the totally dominating ingredient is wood, the research and development (R&D) efforts within the particle-board industry has, up to mid 80's almost exclusively been dealing with the binders and the role of the wood has been neglected.
It is well known in the pulp and paper industry that the wood must be stored for a certain time before the production of pulp takes place to avoid quality and process problems. During storage wood undergoes important changes in the chemical composition. For instance, some volatile compounds disappear, the amounts of free and bonded acids increase, unsaturated bonds oxidize, hydrolysis of esters will occur, etc.
The particleboard industry has, however, not paid these facts much attention, but instead concluded that process and quality problems are more likely to stem from variations in the binder quality.
Up to now it has not been possible to establish valid correlations between the analysis result of the wood material and the properties of the board, even though there would seem to be a certain con

REFERENCES:
patent: 4800279 (1989-01-01), Hieftje et al.
patent: 5360972 (1994-11-01), DiFoggio et al.
patent: 5536942 (1996-07-01), Barringer et al.
Meder et al., "Prediction of Wood Chip and Pulp and Paper Properties Via Multivariate Analysis of Spectral Data", Abstract No. 00393878, 48th Appita Annual General Conference, Melbourne, Australia, May 1994.
Meder et al., "Prediction of Wood Chip and Pulp and Paper Properties Via Multivariate Analysis of Spectral Data", Abstract No. 0572677, 48th Appita Annual General Conference, Melbourne, Australia, May 1994.
P. Niemz et al., "Orientierende Untersuchungen zur . . . " Holtz als Roh-und Werkstoff 50 (1992) 25-28.
C. Kniest, "Charakterisierung von Span-Leim-Gemischen . . . " Holtz als Roh-und Werkstoff 50 (1992) 73-78.
S. D. Brown, "Chemometrics" Anal. chem. 1990 62:84R-101R.

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