AFTER-CARE OF WOODEN MASTS, POSTS AND THE LIKE, AND AN AGENT FOR THIS PURPOSE

METHODE ET PRODUIT DE TRAITEMENT POUR MATS, PLATEAUX ET AUTRES OBJETS SIMILAIRES, EN BOIS

English Abstract

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Abstract of the Disclosure: An agent for the after-care or
treatment of the heartwood of wooden masts and the like,
based on a chemical compound which releases methyl iso-
thiocyanate, contains tetrahydro-3,5-dimethyl-2H-1,3,5-
thiadiazine-2-thione (dazomet) and an essentially anhydrous
solvent or dispersant, with the proviso that the mixing
ratio and intrinsic viscosity of the solvent or dispersant
and, where relevant, the concomitant use of a thickener
result in the said agent having a pasty consistency.

Claims

The embodiments of the invention in which an
exclusive property or privilege is claimed, are defined
as follows:
1. An agent for the after-care or treatment
of the heartwood of wooden masts and similar wood articles,
based on a chemical compound which releases methyl isothio-
cyanate, wherein the said agent contains tetrahydro-3,5-
dimethyl-2H-1,3,5-thiadiazine-2-thione (dazomet) together
with an essentially anhydrous solvent or dispersant, with
the proviso that the mixing ratio and intrinsic viscosity
of the solvent or dispersant result in the said agent having
a pasty consistency.
2. An agent as claimed in claim 1, wherein
dazomet is contained in an amount equal to or higher than
10% by weight.
3. An agent as claimed in claim 2, containing
from 25 to 50% by weight of dazomet.
4. An agent as claimed in claim 1, 2 or 3,
wherein the dispersant is a polyglycol.
5. An agent as claimed in claim 1, 2 or 3,
wherein the dispersant is polypropylene glycol.
6. An agent as claimed in claim 1, 2 or 3,
further containing a heavy metal compound as a stabilizer.
7. An agent as claimed in claim 1, 2 or 3,
further containing a zinc compound as a stabilizer.
8. An agent as claimed in claim 1, 2 or 3,

further containing a sparingly volatile amine.
9. An agent as claimed in claim 1, 2 or 3,
further containing alkylarylsulfonate as a wetting agent.
10. An agent as claimed in claim 1, 2 or 3,
further containing a thickener.
11. A method of preserving wooden masts, compri-
sing the steps of drilling bore holes in the masts reaching
the heartwood region thereof, and filling said bore holes
with an agent as claimed in claim 1.
12. A method as claimed in claim 11, comprising
the additional step of closing the bore holes after they
are filled.

Description

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O.Z. 0975/00031
A~ter-care of wooden masts, posts and the like,
and an agent for_this purpose
-
Wooden poles and similar wooden structural elements
which are to be inserted into the ground are protected
from wood-destroying fungi and animals by treatment with
fungicides and/or insecticides.
Examples of conventional agents of this type are
copper compounds, boron compounds, chromium compounds,
arsenic compounds and other heavy metal compounds, organic
compounds having a non-specific action, such as tar oils,
and a large number of substances whose action is more or
less specific.
The conventional treatment of the wooden
elements comprises impregnation, usually while alternately
reducing and increasing the external pressure (pressure
impregnation). The disadvantage of pressure impregnation
is that many types of wood are radially permeable to
liquid only in the sapwood. Hence, the impregnation does
not reach the heartwood, which is preferentially attacked
by very special fungi, ie. heartwood-specific fungi, and
then exhibits damage typical of heart rot or inner rot.
It has been proposed ~o impregnate the heartwood after
perforating the trunk, or to impregnate the freshly felled
trunk from the point of cutting. However, these methods
have proven unfeasible.
It is therefore usual to make ~he heartwood region
accessible through isolated bore holes, ie. a relati~ely
small number of appropriate wide bore holes, and to pro-
vide the bore holes with a stock of impregnating agent
and close them with a plug~ This method is used in parti-
cular for after-care; ~hus, after standing for a number
of years, the trunk is once again dug out, or the buried
foot is bared, holes are drilled in the trunk and the
latter is appropriately treated.
Agents convent;onally used for after-care are
those which release readily diffusing biocidal substances;

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an agent of this type cons;sts of, for example, an aqueous
solution of Na N~methyldithiocarbamate, which decomposes
to give the biocidal methyl isothiocyanate.
Since deconposition begins on contact with
water, Na N-methyldithiocarbamate decomposes even in
aqueous solution.
It is an object of the invention to provide an
agent which, in the trunk, is intended to become active
only ;n the presence of the moisture that causes inner rot,
in dry wood, the agent should remain as a reserve.
We have found an agent which releases diffusable
biocidal substances only in the presence of moisture, and
which is based on tetrahydro-3,5-d;methyl-2H-1,3,5-thia-
diazine-2-thione, whose usual common name is dazomet.
Dazomet is used for decontaminatina soil and for the
fungicidal treatment of, for example, paper sizes and the
like, and releases methyl isothiocyanate on contact with
water.
According to the invention, the agent is used in
an essentially anhydrous form; for this purpose, it con-
tains, in addition to dazomet, an anhydrous solvent or
dispersant and, preferably, also a stabilizer which pre-
¦vents the premature decomposition of the dazomet to form
methyl isothiocyanate.
~5 The anhydrous solvent or dispersant used is, for
example, a polyglycol~ preferably polypropylene glycol.
According to the manufacturers, polyglycols having a suit~
able viscosity have a mean molecular weight ~v (viscos;ty
average) of about 600 - 1,000.
A group of dispersants which is also suitable is
that comprising the cationic wetting agents and dispers-
ants of the benzylammonium salt type. These compounds
themselves have a biocidal action, and, in anhydrous form,
are more or less viscous liquids.
The amount of dazomet in the dispersion is in gene-
ral more than 10, eg. from 25 to 50, % by weight~ based on
~the total weight of the agent.
The stabilizer used can be a heavy metal compoundr

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for example a zinc compound~ the novel agent of which should
contain in general an effective amount of less than S % by
weight. The term compound is understood as meaning, for
example, a salt, an oxide or a hydroxide. Zinc oxide is
a very suitable zinc compound.
The action of the heavy metal compound is j~-
proved by the addition of a sparingly volatile amine, 'or
example an alkanolamine, eg. monoethanolamine. The amount
present in the agent is in general from 1 to 5 X by weight~
1û The wettabil;ty of the novel agent can, if required,
be improved by adding a conventional ionic or non-ionic
wetting agent, for example an alkali metal salt of an
alkylarylsulfonate. This is present in general in an
amount of less than 10 % by weight, based on the novel
agent.
Agents envisaged by the invention generally have
a pasty consistency and are applied by apparatuses already
availableO An example of such an apparatus is an
inoculation gun. A bore hole which has been produced
beforehand can be filled using other apparatuses.
Examples of formulations which give agents accord-
ing to the invention are described below; the agent is
obtained in each case by stirring or kneading the compon~
ents.
EXAMPLE 1
50 % of dazomet and
50 % of triethylene glycol (solvent).
EXAMPLE 2
50 % of da~omet and0 50 ~ of phenylglycol (active solvent).
EXAMPLE 3
S0 % of dazomet,
49 % of polypropylene glycol and
1 ~ of ~inc oxide.

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EXAMPLE 4
50 % of dazomet,
49 X of triethylene ~lycol and
1 X of monoethanolamine.
SEXAI~PLE 5
50 % of dazomet,
47 X of polypropylene glycol and
3 % of salts of dodecylbenzenesulfonic acid.