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Патент USA US2291336

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2,291,336
Patented July 28, 1942
UNHTED STATES
2,291,336
METHOD OF PREPARING WOOD
IIVIPREGNANT
Jacquelin E. Harvey, Jr., Atlanta, Ga., assignor of
one-half to Southern Wood Preserving Com
pany, East Point, Ga., a corporation of Georgia
No Drawing. Application February 10, 1941,
Serial No. 378,307
(Cl. 196-63)
1 Claim.
clude the elimination of the apparent toxicity
The present process relates to the elimination,
blanketing effect in the entire residue above
at least partial, of the toxicity blanketing e?ect
270° C. or any fractional part thereof, for it has
in wood preserving impregnants.
been shown that bene?cial toxic results are ac
In the preparation of wood preserving im
complished by eliminating or lowering the toxic
pregnants from oils of aromatic content, it has U1 ity blanketing effect in only a portion of the
long been a desideratum in the art to provide a
residue above 270° C., as for instance the residue
above 355° C.
There are, perhaps, many reasons attaching to
the decrease of toxicity as the residue above
270° C. increases, which, however, is of no con
cern to the development of the data at hand.
It is now discovered that, perhaps among other
things, the character of the residue above 270° C.
preserving impregnant of maximum toxic prop
erties without sacri?cing permanency. How
ever, research has disclosed that maximum toxic
properties and good permanency of Wood pre
serving impregnant are not always compatible.
To secure a high toxic e?iciency of a wood pre
serving impregnant, the permanency of the im
pregnant must, to a certain degree, be sacri?ced.
The converse is true.
15 influences the reduction of toxicity.
In wood
preserving impregnants of the oil type, as for
instance impregnants of the tar-derived type, the
As an‘ example of a wood preserving impreg
nant of high toxic properties, but of relatively
fractions above 270° C. contain in varying per
low permanency, may be mentioned a coal tar
creosote, identi?cation No. 7838, having 47.7%
distilling above 270° C. and a killing concentra
centages oxygen-containing compounds,
tion of 0.075%. By killing concentration is
meant the percentage of the wood preserving im
pregnant required to kill wood destroying fungi
and is fully described on page 2 under the cap
tion “Method of conducting the test,” in Techni
cal Bulletin No. 346, March, 1933, U. S. Depart
ment of Agriculture.
In the tabular data shown below are listed sev
eral woo-d preserving impregnants and the indi
cated relationship between their residue above
270° C. and their respective killing concentra
tions.
I
_
Impregnant identi?cation No.
7838 _________________________________________ _ _
Killing
Residue
concentration
above
270° 0
Per cent
Per cent
0. 075
0.150
0.350
2. 500
47. 7
56. 7
73. 0
85. 0
of the impregnant in question.
Research has disclosed that the toxicity
blanketing effect of the residue above 270° C.
may be eliminated, at least to a degree, by the
decomposition or partial decomposition of the
oxygenated compounds contained in said residue.
The following examples will serve to illustrate
modes of practicing the process, but are not to
be construed as limitations inasmuch as those
skilled in the art will readily recognize that the
present process is possible of many variations.
Example 1.-—A coal tar creosote having an
oxygen containing residue of 47.7% above 270° C.
and a killing concentration of 0.075% is stripped
to remove the residue above 270° C. The residue
is treated with hydrogen at 400° C. and 275 at
mospheres pressure for one hour, the while in
cluding the presence of a catalyst selected from
the group consisting of halogens, halids and de
40 rivatives thereof. By the inclusion of said cata
lyst oxygenated compounds are decomposed.
As indicated by the tabular data shown above,
the impregnant having the highest residue above
270° C. is the least toxic and those having the
“a. 5
lowest residue above 270° C. are the most toxic.
However, those having the least residue above
270° C. are the least permanent in the Wood
treated therewith. Many and divergent theories
have been advance-d for the decrease in toxicity
as the residue in the impregnant above 270° C.
increases.
The present process is concerned with a novel
manner of eliminating, at least to a degree, the
apparent toxicity blanketing e?ect of the residue
above 270° C., which statement is meant to in
the
20 presence of which tends to blanket the toxicity
The treated residue of lowered oxygen content
is blended with the originally stripped low boil
ing material to provide an overall toxic material
having a killing concentration of less than
0.075%.
EmampZe 2.-—A coal tar having an oxygen con
taining residue of 85% above 270° C. and a kill
ing concentration of 2.5% is stripped to remove
the residue above 270° C. The residue is treated
with hydrogen at 410° C. and 300 atmospheres
pressure for one and one-half hours, with the
inclusion of three tenths percent iodine based
on the weight of the residue. By the aid of the
55
inclusion of said iodine, oxygenated compounds
2
2,291,336
are decomposed at least partially. The treated
residue of lowered oxygen content is then com
mingled with the originally stripped 10w boil
ing material to provide an overall toxic material
having a killing concentration of less than 2.5%.
Example 3.—~A coal tar is distilled to substan
toxic material having a killing concentration of
less than 0.31%.
Viewed broadly, the present invention provides
a process for decomposing at least a portion of
the oxygen containing compounds contained in
said residue above 270° C‘. of toxic materials
whose toxic efficiency is blanketed by the presence
of'said oxygenated compounds.
tial dryness to provide a creosote having an oxy
gen containing residue of 73% above 270° ‘C'. and
a killing concentration of 0.35%. As the creo
Pressures and temperatures of in excess of 100
sote is being recovered from the coal tar it is cut 10
atmospheres and 300° C., respectively, are pre
into two portions, the out being made at substan
ferred. However lower pressures and tempera
tially 345° C. The residue above 345° C‘. is sub
tures may be used but the time element will be
jected to the action of hydrogen at 415° C‘. and
extended.
a pressure of 200 atmospheres for a period of
Minor changes may be made within the scope
one hour, the while including a catalyst adapted 15
of the appended claim without departing from
to in?uence the decomposition of oxygen con
the spirit of the invention.
taining compounds, said catalyst being selected
I claim:
from the group consisting of halogens, halids
In
the diminution of toxicity-blanketing effect
and derivatives thereof. The treated residue of
lowered oxygen content is then commingled with 20 in a high temperature coal tar creosote due to
oxygenated compounds contained in the residual
the low boiling portion of the creosote previously
material
boiling above 270° 0., the process which
cut to provide an overall toxic material having
comprises: stripping said creosote at a tempera
a killing concentration of less than 0.035%.
ture not below 270° 0. to provide a distillate and
Example 4.-A high residue creosote having
a
residual having oxygen-containing fractions;
substantially 75% residue above 270° C. and a
said residual to a single action of hy
killing concentration of substantially 0.3% is 25 subjecting
drogen catalyzed by a catalyst selected from the
stripped up to: 355° C. to provide a residue char
group consisting of halogens, halids and deriva
acterized by oxygen containing compounds that
tives
thereof, said catalyst adapted to in?uence
blanket toxicity in the parent material. The oxy
gen containing residue is treated with hydrogen 30 the elimination of oxygen from said oxygen-con
in the presence of a catalyst selected from the
taining residual; continuing the treatment for
such a length of time and with pressure and tem
perature so chosen as to provide at least partial
elimination of oxygen from said residual; distill
ing the treated residual to provide a newly formed
group consisting of halogens, halids and deriva
tives thereof; time of treatment, two and one
quarter hours and pressure 300 atmospheres.
The treated residue of lowered oxygen content is 35
residual having an initial boiling point similar to
distilled to an upper limit to provide a residue
the high boiling point of the distillate ?rst
having an initial boiling point similar to the high
"named; and commingling the residue last named
boiling point of the distillate previously recovered
with the distillate ?rst named whereby to provide
from the high residue creosote starting material.
a toxic material having a smaller killing con
The distillate ?rst recovered and the residue last 40 centration
than the parent material.
named are commingled to provide an overall
JACQUELIN El. HARVEY, JR.
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