Note: Descriptions are shown in the official language in which they were submitted.
1~0~9S2
WOOD PRESERVATIVE CO~lPOSITION
This invention relates to a wood preservative
composltion primarily intended to protect wood from
mildew.
A large proportion of cut lumber is treated
with a chemical compound to protect against rot and
mildew ~which latter term is used to include fungi). For
about the past 40 years, sodium penta and tetrach-
lorophenates have been used in the lumber industry almost
exclusively for the foregoing purpose. However, with the
discovery of carcinogenic dioxins in the penta and
tetrachlorophenates, it is becoming increasingly unde-
sirable to use such compounds.
Aqueous wax emulsions have been also utilized
in the past for treating cut lumber, the purpose of such
treatment being primarily to coat such lumber with a
layer of wax. Such a layer of wax helps the lumber main-
tain a clean, bright appearance by repelling water and
dirt, thereby keeping the lumber clean and dry par-
; 20 ticularly during overland transport. Such compositions
exhibit some mildewicide properties, which primarily
arise by maintaining the wood dry so as to be less
attractive to mildew attack, and by creating a barrier
between the wood and spores. However, any such inciden-
tal mildew protection offered by such compositions is
unsatisfactory for most uses.
~ ~2~)'79~
The compound (2 thiocyanomethythio)
benzothiazole (which is often abbreviated as T.C.M.T.B.)
is a known mildewicide which can be utilized on cut
lumber. However, such compound does not produce satis-
factory mildew inhibition unless it is at a concentration
in the solution in which the lumber is normally dipped,
of at least about 1%, and preferably about 2%. Although
T~CoM~T~B~ does not have the drawback of sodium penta and
tetrachlorophenates as mentioned above, T.C.M.T.B. is
considerably more expensive than the latter compounds and
at the foregoing concentrations would result in a cost
about 10 to 20 times higher, respectively, than suitable
amounts of penta and tetrachlorophenates to obtain the
same mildewicide effect.
It is desirable then, to have a wood preser-
vative composition which can repel water and dirt, while
at the same time acting as a mildewicide by virtue of the
presence of preferably low concentrations of a suitable
biocide (i.e. mildewicide) either than the sodium penta
and tetrachlorophenates, and which is not overly
expensive.
A wood preservative composition is provided,
which comprises a wax, and a biocide dispersed in the
wax. The foregoing biocide is usefully selected from the
group consisting of (2 Thiocyanomethythio) benzothiazole,
methylene bis thiocyanate, and 3-iodo-2-propyln butyl
352
carbamate. Of the foregoing compounds, the
(2-thiocyanomethythio) benzothiazole is preferred.
The wax usefully comprises a mixture of paraf-
fin wax and polyethylene wax. The composition preferably
additionally comprises water in which the wax/biocide
dispersion is in turn dispersed, in the form of an
emulsion.
Additionally, the composition usefully compri-
ses a sufficient amount of an amine based soap so as to
maintain the wax biocide dispersion as an emulsion in the
water.
Preferably, the amine based soap is selected
from the group consisting of morpholine and ethanolamine
based soaps (which latter term includes monoethanolamine,
diethanolamine, and triethanolamine based soaps). It is
further preferred that a sufficient amount of a base be
present so as to stabalize the emulsion of the
wax/biocide dispersion in the water. Usefully, a
defoamer is additionally preferably provided.
A method of producing the foregoing wood pre-
servative is also provided, which comprises dispersing a
biocide in a hot liquid wax, and adding a soap to the hot
liquid wax. Then, the product of the foregoing steps is
dispersed in water by adding hot water thereto and
mixing, so as to produce an emulsion. A sufficient
amount of a base is preferably provided, either before or
1207~5~
after adding of the hot water, so as to produce a com-
position with a pH between about 10.4 and 10.6.
It has been found that when water emulsions of
wax/biocide dispersions are used to coat cut lumber, a
moisture repellancy is obtained as one would expect, but
in addition a synergistic mildewicide activity is
obtained, the composition as a whole being a more efEec-
tive mildewicide -than either a water emulsion of the wax
alone at the same concentration, or the biocide alone at
the same concentration.
Table 1 below shows the components in a typical
wood preservative composition of the present invention:
~Z0~795;2
TABLE 1
Item Weight (lbs)
Slack wax (i.e. last fraction
of paraffin oils and first part
of paraffin waxes) 234.87
Polyethylene wax 84.64
PAMAK W4 (a trade mark of
Hercules Chemicals Ltd for a mixture
of soya fatty acids) 27.27
T.C.M.T.B. 37.45
Caustic flake 3.55
Ethylene glycol 1.23
Morpholene 35.24
Boiling water 548.83
H-10 emulsion ~a trade mark of
Dow Coini~g Chemicals for a
silicone emulsion type defoamer) .28
NOPCO NDW ( a trade mark of
Diamond Shamrock CoO for a
mineral oil based emulsion
defoamer) .50
TRITON CF-10 ( a trade mark of
Rohm and Haas Co for a nonylphenyl
surfactant) - 2.34
C888 yellow oxide C (a trade mark
of Tenneco Canada Inc. for a water
based pigment dispersion) 36.89
The above composition was made by heating and
; 25 mixing together all of the components in the table prior
to the water, at a temperature of about 250F to produce
a dispersion of the biocide, T.C.M.T.B. in the hot liquid
~LZ~t795~
wax (the word "dispersion" or the corresonding verb
"dispersing" being used throughout this application to
include the production of a solution or suspension). The
boiling water was then added to, and mixed with, the
foregoing product so as to produce an emulsion. It
should be noted at this point that adding the hot liquid
wax composition to boiling water does not produce a
satisfactory emulsion. The remainder of the ingredients
can be added following addition of the boiling water.
The polyethylene wax is utilized in the above
composition in order to harden the overall mixture of the
slack wax, which in itself is very soft, and polyethylene
wax. During production the T.C.M.T.B. becomes dispersed
in the mixture of the hot liquid wax. The soya fatty
acids on the other hand react with the morpholene to pro-
duce a morpholene based soap which acts as an emulsifier
to maintain the wax/biocide dispersion in a water
emulsion Eollowing addition of the water. The caustic
flake is added so as to result in a final water emulsion
which is alkaline so as to maintain the stability of the
particular type of emulsion formed. Ethylene glycol is
present to act as an anti-freeze in the final water
emulsion, although it also acts somewhat as a solvent for
the caustic flake when that compound is added prior to
the boiling water. The defoamers serve the usual pur-
pose, whi~e the TRITON CF-10 surfactant improves colour
lZ0795~
acceptance (miscibility) of the pigment C888 yellow oxide
C~ or any other pigment used, if any.
Various compositions analogous to that described
in Table 1 above have been made and used for treating
cut lumber. In particular, the biocide T.C.M.T.B. has
been replaced by the biocide 3-iodo-2-propylene butyl
carbamate (sometimes referred to in this application
as 3-iodo-2-propylon butyl carbamate) sold under the
trade mark POLYPHASE (a trade mark of Troy Chemical Co.,
New York), and methylene bis thiocyanate (often referred
to in this application simply as M.B.T.). The weight
percentage of the biocide in the above composition is
changed simply by changing the weight of it added during
production of the composition, with the weight of other
components remaining the same.
A number of tests were conducted with cut lumber
packages dipped in various mildewicide compositions
as well as compositions analogous to that of Table 1
with the only exception being that the amount or type
of biocide was varied as noted, and the TRITON CF-10
and C888 yellow oxide C were deleted. All of the lumber
packages listed in Table 2 were created by utilizing
lumber of mixed grade fir/hemlock two by fours which was
purchased directly from a sawmill to ensure against any
previous chemical treatment. In each case, the package
was bundled in four foot lengths consisting of 16 pieces
in rolls four wide. Each bundle was loosely strapped and
, ~.
. ~LZ~9~
dipped in the indica-ted solution for a period of one
minute while being constantly rotated to avoid air
pockets.
3LZ07~5Z
TABLE 2
_ckage No. Treatment Solution
1 .8% T.C.M.T.B.
2 1.0% T.C.M.T.B.
3 .8% polyphase (a trade mark of
Troy Chemical Co, New York for
3-iodo 2-propyln butyl carbamate)
4 1.0% Polyphase
.8~ M.B.T.
6 1.0% M.B.T.
7 .8~ WOOD BRITE 24 (a trade mark
for sodium penta chlorophenate)
8 control (no treatment)
9 .015% KATHON (a trade mark of Rohn
and Haas Company for 2-n-octyl-4
isothiazoline-3-one)
.08% KATHON
11 .7% phenylmercuric acetate
12 Table 1 composition but with no
biocide present.
13 Table 1 composition with .2%
T.C.M.T.B.
14 Table 1 composition with .4%
T.C.M.T.B.
Table 1 composition with .2%
polyphase
16 Table 1 composition with .4%
polyphase
17 Table 1 composition with .2%
M.B.T.
: 18 Table 1 composition with .4
M.B.T.
,
:,
lZ079S~
Each of the above packages were then allowed to
dry before being located in a grassy, damp location in
Surrey, British Columbia, Canada so that the exterior of
the packages were open to the environment. Each package
was weighed and inspected prior to exposure for future
weight loss calculation purposes. All of the packages
were left in position for the same eight month test.
Commencing in February and concluding in October of the
same year. Following termination of the tests, each
package was opened and independently examined by three
inspectors for incidents of sap stain (staining of the
wood caused by mildew), mildew growth (which was examined
for by both visual and microscopic scanning), and amount
of free water remaining inside the package. The packages
were categorized in two groups, group I consisting oE
packages 1 through 11, and group II consisting of packa-
ges 12 through 18. The packages in each group were given
a numerical rating in terms of their relative performance
within their respective groups. That is, numbered 11
down to 1 for the best to worst packages in group I, and
from 7 down to 1 or the best to worst packages in group
II. In addition, each of the packages were assigned
total points, which were in each case the weighted sum of
points awarded by the inspectors for mildew resistance,
stain resistance, weight loss, and water content. In the
case of packages in group I, the weighting to establish
total points was as follows:
~2079SZ
Mildew resistance 36~
Stain resistance 32%
Weight loss 18%
Water content 14%
With regard to group II, more emphasis was
placed on weight loss and water content in establishing
the total points, as customers using such a product would
have a greater interest in these factors than they would
if they were simply using a product of group I, since
they would not be using the latter product in any event
to inhibit water absorption. The weighting to establish
total points in group II was as follows:
Mildew resistance 29%
Stain resistance 26%
Weight loss 26%
Water content 19%
The results obtained from the inspectors were
averaged for each parameter, with the final average
results being calculated in Table 4 on the following
page.
11
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It will be seen from Table 4 that the com-
positions used in the packages of group II, on the
average resulted in less absorption of water. In addi-
tion though, it will be seen that in the case of each
biocide used in the compositions for the packages of
group II, far better stain and mildew characteristics are
exhibited with the presence of .2% of the biocides indi-
cated, then was exhibited with the presence of .8% of
corresponding biocides in the compositions of group I,
which lacked the presence of the wax. In addition
though, it will be seen from Table 4 and bearing in mind
the manner in which the weighted total points are calcu-
lated, that the effect of combining .2% of the biocides
with the remainder of the components of Table 1 in the
manner described, produces a synergistic mildewicide
effect. It will also be seen from Table 4, that in each
of the biocides tested, the presence of .2~ of such
biocide produced a better effect in the group II com-
positions that did the presence of .4% of the same
biocide.
Various alterations to the composition of Table
1, aside from those already mentioned, can be made and
still result in a composition which has relatively useful
mildewicide properties for cut wood. For example,
another soap than that formed between the soya fatty
acids and morpholene might be utilized. For example, a
``~'` 120795Z
soap formed between such fatty acids and triethanolamine
produced a composition which worked but not as well as
that described in Table 1. More fatty acid is necessary
when triethanolamine is used to replace morpholene, since
the pH of the former is higher. In addition, triethano-
lamine is not as volatile as is morpholene, so that any
excess triethanolamine does not readily vaporize and
leave the composition after applied to lumber.
Morpholene on the other hand is volatile and any excess
morpholine relativel~ readily vaporizes and diffuses out
of the composition after it is applied to lumber. This
is a particular advantage since morpholine and other ami-
nes tend to be hydrophyllic to some extent, and the pre-
sence of excess amine would tend to increase water
absorption which in turn could result in increased
mildew.
Diethanolamine in place of morpholine on the
other hand, produces a water emulsion in the final pre-
servative composition, which composition solidifies.
Monoethanolamine in place of morpholine produced a wood
preservative composition emulsion, however such emulsion
was heat unstable. Ammoniam h~droxide could also be used
to replace morpholine, however due to the temperatures
involved, as described in the above process, is difficult
to handle and much of the ammonia vaporizes durin~ the
process.
14
~20795~
Amino-methyl propanol was substituted for
morpholine with some success, but the final preservative
composition was in the form of a paste. Such a paste is
difficult to break up and indicates a poorer emulsion.
Stearic acid was also utilized, however the final preser-
vative composition solidified at room temperature. Some
of the above, as well as further emulsifying systems were
also attempted as shown below in Table 3. Each com-
position in Table 3 was made up the same as that in
Table 1, with the exception that the PAMAK W4 (soya fatty
acids~ and morpholine were replaced with the amounts of
ingredients listed in Table 3. Where the resulting com-
position has a performance indicated as "separated", this
means that the emulsion separated within a period of 7 days.
~07952
TABLE 3
Wt. % Based On
Trial Components Used Wax Solids Performance
1 Stearic Acid 20 Gelled
Triethanolamine 7.6
2 Soya fatty acids 17.82 Stable but
foamed exces-
sively
q~riethanolamine 23.28
3 REXOL 25 JWCl3.3 Separated
Morpholine 19.2
4 INTERWET 332 3 Separated
BUTYL CELLoSOLVE3 10
TRITON CF-104 2.0 Gelled on
cooling
TRITON X-100510.65
6 ATLOX 8404F6) Various Separated
ATLOX 3409 F7
7 PAMAK W_48 12.6 Stable emul-
sion
Monoethanolamine 17.3
8 PAMAK W_48 12.6 Stable emul-
sion
Mixed Isopropano- 17.3
lamines
9 TRITON GP-79 ) Separated
TRITON N-10110) Various
TRITON x-4511 )
1 REXOL 25 JWC is a trade mark of Hart Chemical Co.
for nonyl phenoxy polyoxethylene ethanol.
2 INTERWET 33 is a trade mark of Interstab Chemicals
Ltd. for a nonionic surfactant consisting of nonyl
~5 phenyl polyethoxy ~thanol, containing 68% ethylene
oxide by weight.
3 BUTYL CELLOSOLVE is a trade mark is Union Carbide
for an ethylene glycol mono butyl ether.
16
~, .
^`~ lZ0~5Z
4,5 TRITON CF-10 and TRITON X-100 are trade marks of
Rohm and Haas Co. for respectively, a nonionic alky-
laryl polyether and a nonionic isooctyl phenyl
polyethoxy ethanal having 9 to 10 moles of ethylene
oxide per mole of isooctyl phenyl.
6,7 ATLOX 3404F and ATLOX 3409F are trade marks of
Atlast Chemical Company for anionic polyoxethylene
derivatives, having respectively a low hydrophyllic
lithophillic bonding, and a high hydrophyllic
lithophillic bonding.
8 PAMAK W-4 is a trade mark of Hercules Chemicals Ltd.
for a mixture of soya fatty acids.
9,10,11 TRITON GP-7, TRITON N-101 and TRITON X-45 are
trade marks of Rohm and Haas Company for respec-
tively, an anionic dioct.yl sodium sulfosuccinate,
a nonionic nonylphenyl polyethoxy ethanol having
9 to 10 moles of eth~lene oxide per mole of
nonyphenyl, and a nonionic isooctyl phenyl
polyethoxy ethanol having about 5 moles of ethy-
lene oxide per mole of isooctyl phenyl.
`~ ~.z~79~
With regard to the pH of the preservative com-
position, this can again be varied somewhat although the
particular emulsion produced in the composition of Table
1, an alkaline solution is required in order that the
emulsion is stable. For the emulsion to be stable for a
period of about six to eight months, a pH of at least
about 10.4 is required. A pH above about 10.4 would be
even more desirable except that when the pH is larger
than about 10.6, the wood to which the composition is
applied, becomes discoloured. With regard to other
variations, it will be noted that ethylene glycol can be
omitted if antifreeze is not required, and particularly
is the caustic flake is added after addition of the
water.
As will be apparent to those skilled in the art
in light of the foregoing disclosure, many alterations
and rnodifications are possible in the practice of this
invention without departing from the spirit or scope
thereof. Accordingly, the scope of the invention is to
be construed in accordance with the substance defined by
the following claims.
18
