U.S. patent application number 11/171044 was filed with the patent office on 2007-01-04 for composite wood product, methods for manufacturing the same and methods for determining organic biocide concentration in a composite wood product.
Invention is credited to Marek J. Gnatowski, Christine L. Mah, Gareth Paul Merrick.
Application Number | 20070003747 11/171044 |
Document ID | / |
Family ID | 37561681 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070003747 |
Kind Code |
A1 |
Gnatowski; Marek J. ; et
al. |
January 4, 2007 |
Composite wood product, methods for manufacturing the same and
methods for determining organic biocide concentration in a
composite wood product
Abstract
A composite wood product and methods for manufacturing the same
and determining the concentration and distribution of an organic
biocide within a composite wood product are provided. The organic
biocide may be added to wood elements (i.e., fibers, flakes,
strands, veneers) prior to consolidation and/or heating of the wood
particles to form the composite wood product. A tracer additive may
be mixed with the biocide, or applied separately to the furnish
which is used to produce the composite wood product. The tracer
additive may be detected via, for example, x-ray fluorescence. An
amount of tracer additive detected may correlate to an amount of
organic biocide within the wood elements and/or the composite wood
product.
Inventors: |
Gnatowski; Marek J.;
(Coquitlam, CA) ; Mah; Christine L.; (Vancouver,
CA) ; Merrick; Gareth Paul; (Plymouth, MN) |
Correspondence
Address: |
WEYERHAEUSER COMPANY;INTELLECTUAL PROPERTY DEPT., CH 1J27
P.O. BOX 9777
FEDERAL WAY
WA
98063
US
|
Family ID: |
37561681 |
Appl. No.: |
11/171044 |
Filed: |
June 30, 2005 |
Current U.S.
Class: |
428/292.1 |
Current CPC
Class: |
C08K 5/0058 20130101;
C08K 3/38 20130101; C08L 97/02 20130101; Y10T 428/249924
20150401 |
Class at
Publication: |
428/292.1 |
International
Class: |
D04H 13/00 20060101
D04H013/00 |
Claims
1. A composite wood product comprising: a plurality of wood
particles; a resin applied to the wood particles enabling adhesion
between the wood particles; a biocide applied to the wood
particles; and an additive applied to the wood particles wherein
the additive is detectable when the composite wood product is
subject to an x-ray fluorescence analysis and wherein an amount of
additive detected can be correlated to an amount of biocide within
the composite wood product.
2. The composite wood product of claim 1 being selected from a
group consisting of: oriented strand board, laminated strand
lumber, laminated veneer lumber, parallel strand lumber, plywood,
particle board, fiber board and crushed long-fiber lumber.
3. The composite wood product of claim 1 wherein the biocide is
selected from a group consisting of: a synthetic pyrethroid, a
triazole, a nicotinoid and a fiprole.
4. The composite wood product of claim 1 wherein the additive
contains an element having an atomic weight greater than or equal
to ten.
5. The composite wood product of claim 1 wherein the additive is
selected from a group consisting of: zinc, barium and calcium.
6. The composite wood product of claim 1 wherein the wood particles
are selected from a group consisting of: flour, fibers, fiber
bundles, flakes, chips, wafers, veneers and strands.
7. A method for making a composite wood product comprising the
steps of: providing a plurality of wood particles; applying a resin
to the wood particles enabling adhesion between the wood particles;
applying a biocide and a tracer additive to the wood particles
wherein the tracer additive is detectable when the composite wood
product is subject to x-ray fluorescence spectroscopy and wherein
an amount of tracer additive detected can be correlated to an
amount of biocide within the composite wood product; and heating
and pressing the plurality of wood particles to form the composite
wood product.
8. The method of claim 7 wherein the composite wood product is
selected from a group consisting of: oriented strand board,
laminated strand lumber, laminated veneer lumber, parallel strand
lumber, plywood, particle board, fiber board and crushed long-fiber
lumber.
9. The method of claim 7 wherein the biocide is selected from a
group consisting of a synthetic pyrethroid, a triazole, a
nicotinoid and a fiprole.
10. The method of claim 7 wherein the additive contains an element
having an atomic weight greater than or equal to ten.
11. A method for determining a concentration of an organic biocide
within a plurality of wood particles, the method comprising the
steps of: providing the plurality of wood particles; applying an
organic biocide to the plurality of wood particles; applying an
additive to the plurality of wood particles wherein the additive is
detectable when the plurality of wood particles is subject to an
x-ray fluorescence analysis; subjecting the wood particles to an
x-ray fluorescence analysis; measuring an amount of the additive
detected within the plurality of wood particles; and correlating
the amount of the additive detected to an amount of the organic
biocide within the plurality of wood particles.
12. The method of claim 1 wherein the additive contains an element
having an atomic weight greater than or equal to ten.
13. The method of claim 1 wherein the biocide is selected from a
group consisting of: a synthetic pyrethroid, a triazole, a
nicotinoid and a fiprole.
14. The method of claim 1 wherein the particles are selected from a
group consisting of: flour, fibers, fiber bundles, flakes, chips,
wafers, veneers and strands.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to a composite wood product
and methods for manufacturing composite wood products and
determining a concentration of an organic biocide within a
composite wood product. A tracer element may be added to the
organic biocide prior to composite wood product formation. The
tracer element may be detected via, for example, x-ray fluorescence
spectroscopy. The amount of tracer element detected can be
correlated to the amount of organic biocide within the composite
wood product.
BACKGROUND OF THE INVENTION
[0002] Composite wood products are made from elements or particles
of wood, commonly called furnish, which are consolidated and bonded
together with adhesive resin(s). It should be understood that, in
the present application, the terms "element", "particle" and
"furnish" may be used interchangeably and may refer to any type of
element from which a composite wood product may be manufactured. It
should further be understood that wood composites, as defined in
this specification, refer to those products which maintain the main
properties of wood. Wood elements may include, for example, wood
flour, fiber, fiber bundles, flakes, chips, wafers, strands,
veneers, or combinations of the like. Different grades and/or types
of composite wood products can be manufactured depending on, for
example, the wood species, size of the wood elements, and
processing conditions. The elements are dried to the moisture
content level required by the process. Then adhesive, biocides, and
other types of additives such as, for example, waxes, are applied
to the furnish. This process may occur at one of many stages of
manufacture, but commonly would occur during a process referred to
as blending. Usually the blended furnish is then formed into a mat,
which is then consolidated under heat and pressure to form the
final composite wood product.
[0003] Certain biocides can be applied to the furnish to impart
decay and/or insect resistance in the final product. Biocides
typically used in industrial applications include, for example,
inorganic compounds, such as zinc borate, sodium borate, or
copper-containing salts. Many types of inorganic compounds may be
used as single preservatives, or may be used in combination with
other compounds as co-biocides to treat wood fragments prior to
formation of a composite wood product.
[0004] Controlling biocide additive content may be critical to
ensure proper concentration and distribution of active ingredients
in the product. Uniform biocide distribution across the product
enables economical and proper product protection against insects
and fungi, including decay. Non-uniform concentration or
distribution may lead to partial damage of the product by fungi or
insects. Uniformity of biocide distribution depends on the method
of application. During application, a variety of accidental factors
may appear which may result in non-uniform distribution of biocides
or application of biocides in quantities outside the target range.
Examples of some problems include clogging of a spray nozzle with
dust, contamination in biocide dispersion, a faulty dispensing
system, etc. In a production setting, such as a commercial setting,
it is difficult to quantify uniformity of treatment simply from the
appearance of the blended wood furnish or in the final composite
wood product. As a result, special analytical methods must be
applied to the product to identify active ingredient concentration
and distribution.
[0005] It has been found that wood preservatives containing certain
elements, for example, chlorine, zinc and/or copper and/or chromium
and/or arsenic, could be analyzed relatively quickly without
special sample preparation via x-ray fluorescence spectroscopy
("XRF"). This was particularly the case if such elements were
introduced into the wood product in sufficient concentration (above
1000 ppm, but in some cases as low as 30 ppm). XRF analysis allows
for the non-destructive analysis of a wide range of elements,
typically those heavier than Fluorine (F). The basic principle
behind XRF spectroscopy is the use of an energy source to excite an
inner shell electron of an atom. Energy is applied from a source,
for example an appropriate radioisotope, under which the atom will
emit an x-ray photon (fluoresce). If the applied energy is of
sufficient strength, an electron will be ejected from an inner
ring. This electron will be replaced by an electron from an outer
ring in order to stabilize the atom. The movement of an electron to
stabilize the atom will emit an x-ray photon, which is counted by
the detector.
[0006] It was also found that preservatives containing organic
compounds such as deltamethrin, chlorpyrifos or isothiazolone
require a target application level onto a wood product often as low
as 10 ppm to 2000 ppm. However, elements sensitive to XRF analysis
are not present or present in less than sufficient concentrations
to enable quick accurate analysis of these products. Products
treated with organic biocides require complex sample preparation
and sophisticated analytical methods, such as, for example, High
Performance Liquid Chromatography (HPLC), Gas Chromatography (GC),
or Neutron Activation Analysis (NAA). Even in isolated cases where
sample preparation is not a major issue, these methods require
specialized and expensive equipment, as well as trained personnel.
Neither is readily available or practical in a composite wood
manufacturing facility. The delay associated with such
sophisticated analytical methods can be a major problem because it
potentially allows faulty product to be manufactured without timely
detection of defects. A need, therefore, exists for a method of
determining a concentration and distribution of a biocide within a
composite wood product which is more convenient than known
methods.
SUMMARY OF THE INVENTION
[0007] The present invention generally relates to wood composite
manufacture and methods for indirectly quantifying the
concentration and distribution of an organic biocide within a
composite wood product. A tracer element, or additive, may be added
to the biocide. The resultant mixture may be applied to wood
elements prior to composite wood product formation. The tracer
element may be detected via, for example, x-ray fluorescence
spectroscopy. An amount of tracer element detected can be
correlated to the amount of organic biocide within the composite
wood product.
[0008] It was found that in composite wood products, organic
biocides frequently cannot be detected in target application
quantities in extracts prepared from the final composite products
using known reliable wet chemistry methods. This may likely be a
result, for example, of partial decomposition and/or fixation in
the glue line. Adhesive resins used in wood composites, such as,
for example, phenolics, p-MDI, melamine or urea which become highly
crosslinked, may be a significant factor in an active's fixation.
Such depletion of organic biocides may be directly related to the
product formation, type of adhesive used and/or process conditions.
However, according to the present invention, it has been found,
unexpectedly, that the relationship between the assayed and target
concentrations of tracer elements in composite and the initial
target concentration of additives of interest may be connected
through coefficients of retention, as will be described later in
more detail. This coefficient can be experimentally assessed and
calculated. Coefficient of retention is related to target and assay
concentrations of active ingredients and tracers as identified by
analytical methods in a composite wood product sample. Unexpected
losses of active ingredients during handling and/or the
manufacturing process become visible from the unusually low level
of tracer element detected in the product, and knowledge of the
coefficient of retention allows calculation of the actual
concentration of actives. The constant value of a coefficient of
retention within a relatively wide range of concentration of
additive of interest as discovered makes the analysis described
above relatively accurate.
[0009] The present invention may provide solutions and/or
dispersions carrying organic biocides which may be formulated with
one or more tracer elements that are suitable for XRF analysis. The
quantities may be those required for fast and/or accurate detection
and may enable analysis of concentration and/or distribution of
active ingredient in the composite wood product. To obtain uniform
distribution at the ppm level, in an embodiment, biocides may be
applied to wood fragments in the form of diluted solutions or
dispersions, in concentrations of 0.001 to 10%. These
concentrations may vary depending on the type of composite wood
product, solution and/or dispersion design and/or other conditions
of manufacture.
[0010] The tracer or additive may be mixed with the biocide prior
to application to the wood furnish elements. The tracers
implemented within the solutions and/or dispersions may be, for
example, part of a synergistic biocide formulation. An example of
such a tracer may be, for example, zinc in zinc borate. It was
found that biocides containing metal or other elements sensitive to
XRF analysis, such as, for example, zinc borate, could be prepared
in a blend of powders, or in a dispersion in a common liquid
carrier, such as water, which may also carry one or more biocides.
The use of a liquid dispersion of biocides has several advantages,
such as, for example, lack of dust during handling; more uniform
distribution; and reduction of losses (dislocation) during the
pressing process, particularly when steam injection is used. In
some embodiments, an additional advantage may be that the
formulation has a synergistic effect. For example, a combination of
biocides may be applied to the wood elements and may be monitored
via one or more tracer elements. The combination may be more
effective in protection of composite wood products against insects
or decay in comparison to individual biocides.
[0011] Powder blends or liquid dispersions of the present invention
may be sprayed or applied onto wood elements before entering the
blender, or once inside the blender prior to consolidation into the
composite wood product. It may be possible to apply tracer and
organic biocide separately into the blender using a connected
system of multiple feeders with one feeder dedicated to tracer
distribution and other(s) to additive(s) of interest.
[0012] A first type of analysis may be performed on completed
composite wood product samples. The products may be broken down and
assayed for the presence and distribution of active ingredients
using the XRF technique. A second type of analysis may be conducted
via installation of detection devices on or proximate to a
manufacturing line, prior to compression and/or heating of the
elements to form the composite wood product. The XRF technique may
be applied for continuous monitoring of preservative distribution
on the production line. It could be performed before or after the
pressing operation. Stable preservatives containing metal, or other
XRF sensitive elements, may be directly detected by XRF analysis.
Concentration and distribution in wood composites of organic
co-biocides incapable of being directly detected, can be assessed
indirectly based on XRF analysis data with respect to the tracer
concentration. This can be achieved due to the coefficient of
retention and relationship between tracer assay and target values,
as well as the known target concentration of an additive of
interest. Assessment and calculation for the coefficient of
retention may be established in independent experiments prior to
commercial testing.
[0013] The coefficient of organic biocide retention "K" can be
calculated from the following equation (1):
K=(A.sub.2.times.Z.sub.1)/(A.sub.1.times.Z.sub.2) (1) Where:
[0014] A.sub.1=target concentration of biocide of interest in wood
product
[0015] A.sub.2=assayed concentration of biocide of interest in wood
product
[0016] Z.sub.1=target concentration of tracer element as applied to
composite wood product
[0017] Z.sub.2=assayed concentration of tracer element in wood
product
[0018] The data required for calculation of this coefficient may be
collected from independent samples of formed composite wood
products. The number of samples evaluated for this purpose may
depend on the required accuracy of analysis for treated product,
and the variability of the analytical method used. Accordingly,
when analytical data for the calculation of coefficient of
retention K is more consistent, fewer samples may require
evaluation for calculation of coefficient of retention. The
calculated average from this experiment may be used in assessment
of biocide concentration in samples of interest.
[0019] Based on the above-mentioned coefficient of retention, the
concentration of the biocide of interest in the sample can be
calculated from equation 2 or from a specially prepared calibration
curve: A.sub.x=(K.times.Z.sub.2x.times.A.sub.1x)/Z.sub.1x (2)
Where:
[0020] A.sub.1x=target concentration of biocide of interest in wood
product
[0021] Z.sub.1x=target concentration of tracer element in
sample
[0022] Z.sub.2x=assay of tracer element
[0023] K=coefficient of retention (as described in equation 1)
[0024] It is, therefore, an advantage of the present invention to
provide a method for determining a concentration of an organic
biocide within a composite wood product wherein the method is more
convenient and/or accurate than known methods for determining
organic biocide concentrations.
[0025] Additional features and advantages of the present invention
are described in, and will be apparent from, the detailed
description of the present embodiments and from the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The embodiments of the present invention are described in
detail below with reference to the following drawing.
[0027] FIG. 1 is a flowchart of a method of determining a
concentration of a biocide in an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The present invention relates to composite wood product
manufacture and methods for determining a concentration of an
organic biocide within a composite wood product. A tracer element
may be added to the organic biocide prior to composite wood product
formation. In this regard, the organic biocide and tracer may be
added to wood elements (e.g., fibers, fiber bundles, flakes,
strands, veneers) prior to consolidation of the composite wood
product. It should be understood that use of the words "element",
"fragment" or "particle" references any type of wood furnish from
which a composite wood product is manufactured. It should be
further understood that the term "composite wood product" may refer
to any type of engineered wood product, such as, for example,
medium density fiberboard (MDF), particleboard, oriented strand
board (OSB), waferboard, laminated strand lumber (LSL), plywood,
laminated veneer lumber (LVL), parallel strand lumber (PSL),
crushed long-fiber lumber (scrimber) or combinations of the like.
The tracer element may be detected via, for example, x-ray
fluorescence spectroscopy. An amount of tracer element detected may
correlate to an amount of organic biocide within the composite wood
product.
[0029] The organic biocide may be, for example, a synthetic
pyrethroid (e.g. permethrin, deltamethrin or bifenthrin), a
triazole (e.g. tebuconazole, propiconazole), a nicotinoid (e.g.
imidacloprid), a fiprole (e.g. fipronil) or the like. The additive
may contain, for example, zinc, copper, nickel, cobalt, or any
other element which may be detected via x-ray fluorescence and has
an atomic weight greater than or equal to 10. FIG. 1 illustrates a
flowchart of a method 100 for determining a biocide concentration
within a composite wood product in an embodiment of the present
invention. In a first step, 102, the organic biocide and additive,
or tracer element, may be mixed together. This mixture may occur
in, for example, a powder blend, dispersion, or other medium
suitable for application onto the wood particles comprising the
furnish. In other embodiments, the biocide and additive may be
applied separately to the furnish, such as from differing streams
in a blender system connected to, for example, a common metering
system. In a next step 104, the biocide and the additive may be
applied to wood furnish prior to consolidation under heat and
pressure.
[0030] Decision 106 represents a differentiation between two
embodiments. Namely, in a first embodiment, the wood elements
comprising the furnish are examined on, for example, a forming or
assembly line, prior to compression and/or heating to form the
composite wood product. In a second embodiment, analysis occurs
after formation of the composite wood product. If the elements are
to be examined on the forming line, an x-ray fluorescence system
may be placed adjacent to the elements within the overall system
for manufacturing an engineered composite wood product. An example
of a suitable x-ray fluorescence equipment may be, for example,
obtained from ASOMA.RTM. Instruments, Inc. The x-ray system may
determine a quantity of additive in the wood product, as shown at
step 108. Based on this determination, a concentration and
distribution of biocide in the composite wood sample may also be
calculated, as shown at step 110, using the equations previously
outlined.
[0031] In an alternate embodiment, the elements comprising the
furnish may be compressed and heated, as shown at step 112, after
the biocide and additive mixture is applied. Sufficient time may be
allocated prior to obtaining the composite wood product sample, as
shown at step 114. The sample removed from the composite wood
product may be, for example, ground for testing and may then be
subject to x-ray fluorescence as shown at step 116. In another
embodiment, a core portion of the composite wood product may be
obtained for testing. It is assumed that previous testing of
samples was conducted to determine a value for the coefficient of
organic biocide retention "K" in accordance with Equation 1
mentioned above. The tracer concentration may be obtained as shown
at step 118. Knowing the target concentration of the biocide of
interest, target concentration of tracer element, coefficient K and
assay of a tracer, the concentration of the biocide of interest in
the sample can be calculated from equation 2 as outlined above or
identified from the corresponding calibration curve. This step is
illustrated at 120.
[0032] The invention and procedure of analysis may be described in
the following examples:
EXAMPLE 1
[0033] 11.5 g of NATROSOL.RTM. 250 HB thickener, TAMOL.RTM. 681
(Rohm & Haas) dispersing aid and 11.5 g of BYK.RTM. 031 (BYK
Chemie) defoamer were mixed with 768 g of water using a high speed
disperser. After dissolving the thickener, 2303 g of zinc borate
(BOROGARD.RTM. ZB-US Borax) was added along with an additional 576
g of water and 11.5 g of IGEPAL.RTM. Co 630 surfactant. When the
dispersion became homogenous (with a Hegman grind of 6-7 as per
ASTM D1210), an additional 192 g of water was added, along with 46
g of TIMBOR.RTM. (US Borax), 46 g of Versene (Dow Chemical), 156.7
g of DURSBAN.RTM. R (organic insecticide-Dow Agro) and 746 g of wax
emulsion. Mixing was completed until a uniform dispersion was
obtained. Product was coded as a Preservative ZBDB.
EXAMPLE 2
[0034] 2.8 g of KELZAN.RTM. (Xanthan gum-Kelco), 2.8 g of VAN GEL
B.RTM. (Vanderbilt), 3.8 g of TAMOL.RTM. 681 (Rohm & Haas)
dispersing aid and 3.8 g of BYK.RTM. 031 (BYK Chemie) defoamer were
mixed with 509 g of water using a high speed disperser. To the
homogenous mixture, 1526 g of zinc borate (BOROGARD.RTM. ZB-US
Borax) was added, together with 371 g of water and 7.6 g
IGEPAL.RTM. Co 630. When the dispersion became homogenous, (a
Hegman grind 6-7 as per ASTM D1210), an additional 7.5 g of water
was added, together with TROYSAN.RTM. 174 (Troy) (10% in water).
This was followed by TIMBERTREAT.RTM. DM-5 (Kop-Coat) in quantities
shown in Table 1. Products were coded as a Preservatives ZBDM-1,
ZBDM-3, and ZBDM-4. TABLE-US-00001 TABLE 1 Quantities of
Timbertreat and additional water used in formulation Timbertreat
DM-5 Water Formulations (g) (g) ZBDM-1 50 280 ZBDM-3 165 165 ZBDM-4
330 0
EXAMPLE 3
[0035] 3.20 g KELZAN.TM. (Xanthan gum-Kelco), 7.38 g of TAMOL.RTM.
681 (Rohm & Haas) dispersing aid and 3.70 g of BYK.RTM. 031
(BYK Chemie) defoamer were mixed with 492 g of water using a high
speed disperser. To the homogenous mixture, 1477 g of zinc borate
(BOROGARD.RTM. ZB-US Borax) was added together with an additional
281 g of water and 7.36 g IGEPAL.RTM. Co 630. When the dispersion
became homogenous, (approximately 6-7 a Hegman grind as per ASTM
D1210), 9.8 g TROYSAN.RTM. 173 (Troy) (10% in water) in can
preservative was incorporated into the mixture, together with 239 g
of wax emulsion. An additional 97.5 g of TIMBERTREAT.RTM. DM-5
(Kop-Coat) was then added, and after thorough incorporation of
active into the dispersion, the process was completed. The product
was coded as a Preservative ZBDM-6.
EXAMPLE 4
[0036] 120 lb. of dry aspen strands were loaded into a blender and
sprayed with MDI adhesive for a period of 10 minutes. Resin content
on the strands was targeted at about 5%. This was followed by
spraying of slack wax into the blender as well as addition of the
required quantity of dispersion containing preservative made as
described in examples 1, 2, and 3. Quantities of materials used are
shown in Table 2. Three 2'.times.2' composite wood panels were made
separately from each blender load using a steam injection press
according to standard industry procedure. TABLE-US-00002 TABLE 2
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Components lb. lb. lb. lb.
lb. Wood Strands 200 110 110 110 120 MDI Adhesive 10 5.8 5.8 5.8 6
Preservative ZBDB 6.6 -- -- -- -- ZBDM-1 -- 2.9 -- -- -- ZBDM-3 --
-- 2.9 -- -- ZBDM-4 -- -- -- 2.8 -- ZBDM-6 -- -- -- -- 2.6 Slack
Wax 1.0 0.58 0.58 0.58 0.6
EXAMPLE 5
[0037] Five 2''.times.2'' specimens randomly selected from two out
of three boards made as described in Example 4 were used. The
specimens were ground and assayed for zinc and organic biocide.
Samples of products were ground to approximately 30 mesh size and
analyzed for zinc using a procedure described in the American Wood
Preservative Association Standard A9-01 (XRF method). Organic
biocides were analyzed by extraction from the independent samples.
Samples of ground wood approximately 4 g in weight were Soxhlet
extracted for 6 hours in cellulose thimblets using acetone with 2%
water. Extract was quantitatively transferred to 250 ml volumetric
flasks. 200 .mu.l water was added to 800 .mu.l extract. The sample
was mixed, then filtrated through a 0.45.mu. filter prior to HPLC
analysis.
[0038] HPLC analysis was performed using a Hewlett-Packard HP 1100
HPLC implementing a diode assay detector. UV signal at 230 nm was
used to calculate the reposted results. The analytical column used
was a Zorbax XDB-8 C8, 5 cm.times.4.6 mm id.times.3.mu. particle
size. Flow rate was 0.75 ml/min. The results obtained from the
analysis, and calculated coefficients of retention of organic
biocide, including the average K for trial 1 and the combined
average K for trials 2, 3, and 4, are shown in Table 3.
TABLE-US-00003 TABLE 3 Calculation of coefficient of retention for
organic biocides used in treatment of wood products Target Assay
Organic Zinc Organic Zinc Biocide Content Biocide Coefficient of
Sample (Z.sub.1) (A.sub.1) (Z.sub.2) (A.sub.2) Retention Trial # ID
ppm ppm ppm ppm (K) 1 4.2 1158 6000 1000 3630 388 .64 1 2.5 1158
6000 1000 3465 375 .65 1 2.3 1158 6000 1000 3660 359 .59 1 6.10
1159 6000 1000 4120 365 .53 1 8.7 1159 6000 1000 3810 375 .59
Average for trial 1 .60 2 3.7 1218 4551 11 3388 3.9 .48 2 8.7 1218
4551 11 3388 4.8 .59 2 1.1 1219 4551 11 3426 4.2 .51 2 6.1 1219
4551 11 3388 3.6 .44 3 6.1 1227 4698 38.1 3426 10.2 .37 3 10.1 1227
4698 38.1 3349 14.5 .53 3 3.7 1228 4698 38.1 3542 19.3 .67 3 8.7
1227 4698 38.1 3080 12.3 .49 4 1.1 1230 4385 73.1 3773 29.5 .47 4
10.1 1230 4385 73.1 3175 22.6 .43 4 6.1 1230 4385 73.1 3811 31.5
.50 4 8.7 1230 4385 73.1 3580 30.1 .50 4 6.1 1231 4385 73.1 2965
26.3 .53 Average for trials 2, 3, 4 .50
EXAMPLE 6
[0039] The one remaining panel of the three manufactured from each
furnish formulation as described in Example 4, (and not tested
earlier for coefficient of retention of organic biocides as
described in Example 5), was used. The panels were cut into
2''.times.2'' samples. Two samples from each panel were analyzed
for zinc content using XRF method and the procedure described in
Example 5. Based on these results, and the formula presented
earlier the concentration of organic biocide was calculated using
equation 2. The results are shown in Table 4. TABLE-US-00004 TABLE
4 The concentration in wood products of organic biocides calculated
based on zinc traces assay Assay Organic Organic Target Biocide
Biocide Organic Zinc Concentration Concen- Zinc Biocide Assayed
Calculated tration Trial Sample (Z.sub.1x) (A.sub.1x) (Z.sub.2x)
(A.sub.x) Assayed* # ID ppm ppm ppm ppm ppm 1 6.4 1160 6000 1000
3965 396 418 6.5 1160 6000 1000 3965 396 408 2 1.1 1220 4551 11
3426 4.1 5.5 8.7 1220 4551 11 3580 4.3 4.4 3 6.1 1229 4698 38.1
3503 14.2 10.6 10.1 1229 4698 38.1 3157 12.8 10.1 4 6.1 1232 4385
73.1 3349 27.9 30.3 10.1 1232 4385 73.1 3349 27.9 26.0 5 13 1539
4379 38.6 3619 15.9 14.7 12 1543 4379 38.6 3426 15.1 16.7
*Comparison data obtained from analysis of samples by extraction
and HPLC technique.
[0040] After this evaluation, the remains of samples tested for
zinc borate were assayed for organic biocides using HPLC method as
described in Example 5. The results were compared with those
calculated in the last column of Table 4. The data evidences
reasonable accuracy with respect to calculation of concentration of
organic biocides based on one or more assays of zinc traces and a
determination of a coefficient of retention via experimentation.
This also allows for qualification of distribution of biocide
within the composite wood product. Data presented in Table 3 also
shows constant value of coefficient of retention, within
experimental error, for tested biocides within the wide range of
concentrations used. Small values (K<1) for coefficients of
retentions indicated a significant difference between target and
assayed concentrations of organic biocides observed during the
making of wood composites.
[0041] While the embodiments of the invention have been illustrated
and described, as noted above, many changes can be made without
departing from the spirit and scope of the invention. Accordingly,
the scope of the invention is not limited by the disclosure of the
embodiments. Instead, the invention should be determined entirely
by reference to the claims that follow.
* * * * *