Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
COMPO~IIIQN FOR PRQTEÇ~ING TIMER FRQM FUN~AL Q~OWrH
The present invention relates to a composition for protecting timber
against growth by blue-stain fungi and mold fungi, to the use of said
composition, and to a method of protecting timber against growth by blue-
5 stain fungi and mold fungi.
The fungi which infect timber are subdivided into the three groups
comprising blue-stain fungi, mold fungi and rot fungi. Although blue-stain
fungi and mold fungi do not cause rot, they do cause discolouration and
are able to promote the growth of the fungi which rot wood
1 0 (Basidiomycetes).
The most widely used control agent in this sector is still sodium
pentachlorophenol. However, the use of this biocide is disputed on
account of its presumed negative environmental impact. More recent
compounds, such as methylenebisthiocyanate and 2'-
15 (thiocyanomethylthio)benzothiazole (TCMTB), have various seriousshortcomings, including insolubility in water, temperature instability or
corrosiveness. The most widely used product in the USA, Kopcoat NP-1(~,
comprising 64.8% of a quaternary ammonium cornpound and 7.6% of 3-
iodo-2-propynylbutylcarbamate (IPBC), also has the drawback that the
2 0 IPBC component is poorly soluble in water, so that large amounts of the
other biocide have to be used.
A useful biocide for controlling fungal growth on freshly sawn timber
should be fully water-solubie so as to avoid any precipitation when
dilutions are used or where adsorption on the wood varies. In addition, the
2 5 biocide should not cause discolouration of the wood or interfere with its
further processing, and it must adhere to the sur~ace of the wood with
sufficient tenacity so as not to be washed off by, for example, rain.
Some of these requirements are met by quarternary arnmonium
salts which have long been used as wood preservatives [B.A. Richardson,
3 0 Sapstain Control, Paperi ja puu Nr. 10, S. 613 (1972)]. The usefulness of
aliphatic C6-C11 monocarboxylic acids is also known in this connection
[q.v. US-A-3 995 077 and US-A-4 380 561].
A synergistic composition comprising a quarternary ammonium
compound and an alkali metal salt of an organic carboxylic acid is
3 5 disclosed in US-A-4 585 795 as a wood preservative for inhibiting growth
2 ~
by blue-stain fungi and mold fungi. This composition is able to effect an
enhanced action over that obtained by using the individual substances.
Quarternary phosphonium compounds are also known to have
biocidal activity. Thus EP-A~332 578 teaches the use of a number of
5 tetraalkylammonium and tetraalkylphosphonium salts, including tri-n-butyl-
n-tetradecylphosphonium tetrafluoroborate, as biocides.
The activity of a number of tetraalkylphosphonium bromides and
chlorides, including tri-n-butyl-n-tetradecylphosphonium chloride, as
microbicides for water treatment is disclosed in US-A-4 874 ~26.
Surprisingly, it has now been found that the combination of a
quarternary phosphonium compound with the salt of an organic carboxylic
acid significantly enhances toxicity to fungi. The invention accordingly
relates to a composition comprising such a combination which can be
used with advantage for protecting timber, especially freshly sawn timber,
1~ against growth by blue-stain fungi and mold fungi. -
The novel composition is a mixture comprising at least one
quaternary phosphonium compound of formula [(C4Hg)3P C:n~2n+1]+ X~
or [(C4Hg)3P CnH2n+1]2~ So42-, wherein n is an integer from 8 to 16 and
X- is an anion selected from the group consisting of F-, Cl-, Bf, I-, N03-
2 O and HS04-, and at least one alkali metal salt of an aliphatic C6-C1 2
monocarboxylic acid.
The aliphatic C6-C12 monocarboxylic acid may be seiected from
the group consisling of capronic acid, heptanoic acid, caprylic acid, capric
acid, lauric acid, 2-ethylhexanoic acid, 2-ethylheptanoic acid, and mixtures
2 5 of isomers such as isooctanoic acid or isononanoic acid.
Those compositions are preferred in which the aliphatic
monocarboxylic acid is selected from the group consisting of 2-
ethylhexanoic acid, isononanoic acid, isooctanoic acid, 2-ethylheptanoic
acid, heptanoic acid, capric acid and caprylic acid. (: ompositions
3 0 containing 2-ethylhexanoic acid are especially preferred.
Particularly useful alkali metal salts are the sodium, potassium and
lithium salts. The sodium and potassium salts are preferred, and the
sodium salt is most preferred.
The alkali metal salt can be added per se to the novel composition.
3 5 Alternatively, the acid and the basic alkali metal compound which forms
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the salt with the acid may also be added separately. In this laner case, a
hydroxide carbonate or hydrogencarbonate of an alkali metal will
conveniently be used, preferably an alkali metal hydroxide, such as NaOH.
Acid and alkali metal compound will preferably be added in equivalent
amounts. An excess of one or other component can serve to adjust the pH
to the desired value.
The butyl groups of the phosphonium compound may be straight-
chain or branched. n-Butyl is preferred.
The long chain alkyl group CnH2n+1 of the phosphonium
compound may also be straight-chain or branched. Typical examples of
such groups include 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-
methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-
tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundscyl, dodecyl,
1,1,3,3,5,~-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl or hexadecyl.
1~ Tha long chain alkyi groups may also be mixtures of isomers. Also
possible are mixtures of alkyl groups of different chain length, for example
if customary technical mixtures of alkyl halides and alcohols are used for
$he preparation of the phosphonium compounds.
Preferred compositions are those wherein the long chain alkyl
group CnH2n+1 of the phosphonium compound contains frorn 10 to 16
carbon atoms and is preferably a dodecyl or a tetradecyl group. A
tetradecyl group is especially prsferred.
Also preferred are compositions in which the quaternary
phosphonium compounds have the formula [(C4Hg)3P CnH2n+1]+CI~-
2 5 Particularly preferre~ compositlons are those wherein the
phosphonium compound is tributylphosphoniumtetradecyl chloride.
It is especially advantageous to use the novel compositions for
temporarily protecting freshly sawn timber, i.e. for inhibiting fungal growth
until the timbsr is processed.
3 0 The invention likewise relates to compositions which, in addition to
the aforementioned active ingredients, also contain conventional
formulation auxiliaries. Preferred formulation auxiliaries are water,
alcohols, free carboxylic ackls, includin3 the aliphatic monocarboxylic
acids cited above, and/or bases. The compositions will preferably contain
3 5 an alkali metal hydroxide as base, preferably NaOH. The alcohol will
conveniently be a C1-C4alkanol. A novel composition will typically be
prepared by mixing
(a) 13-4 - 14.5 % of NaOH,
(b) 19 - 22 % of water
(c) 48 - 52 % of an aliphatic monocarboxylic acid
(d) O - 2 % of an alcohol containing 2-4 carbon atoms, and
(e) 14 - 16 % of a 50 % aqu00Us soiution of phosphonium
compound. In (a) to (e) above and throughout this specifica~ion, the
percentages are by weight, unless otherwise indicated. Particularly
preferred compositions are those wherein component (c3 is 2- -
ethylhexanoic acid, component (d) is isopropanol, and component (e) is a
solution of tributylphosphoniumtetradecyl chloride.
Some of the compounds used for the preparation of the
composition, for example the phosphonium halide and the carboxylic acid
1~ salt, are known and are commercially available.
Tha phosphonium compounds present in the novel compositions
can be prepared in a manner known per se. The procedure typically
comprises reacting appropriate phosphonium halides with salts, such as
alkali metal salts, which contain the desired anions, to give the
2 O corresponding phosphonium salts of this invention in which X~ is not a
halide. Typically, sodium nitrate can be reacted with a quarternary
phosphonium halide (C4Hg)3P CnH2n+1 Hal (Hal=halogen). The
reaction conditions are not critical and the reaction can be carried out
under normal pressure and at room temperature and with water as solvent.
2 5 Wsrking up is also carried out by per se known methods, and the reaction
products can be extraoted with an organic solvent and obtained in pure
form after removal of the solvent by distillation. Suitable solvents are
dichloromethane or ethyl acetate. The starting materials are also known
per se and some are commercial products.
3 O Corresponding phosphonium hydrogensulfates can be obtained
typically by reacting the rhodanides with concentrated sulfuric acid,
accompanied by evolution of COS. Working up is then conveniently
carried out by stirring in ice-water and thereafter stripping off volatile
constituents under vacuum. The rhodanides may be obtained by the
3 5 method described above in connection with the nitrates.
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The salt of the aliphatic monocarboxylic acid can be used either per
so or formed from the corresponcling free acid and a suitable alkali metal
compound, such as an alkali metai hydroxide. The novel composition is
conveniently obtained initially in the form of a concentrate with contains the
S phosphonium compound in a concentration of 1 to 40 % by weight and the
alkali metal carboxylate in a concentration of 10 to 90 % by weight . The
composition is convenientiy prepared by mixing the individual
components, preferably by dissolving the active ingredients (or their
- precursors, carboxylic acid and, preferably, alkali metal hydroxide in the
10 case of the carboxylate) in water, with or without the addition of an alcohol.
The weight ratio of phosphonium compound:free carboxylic acid in the
novel compositions is conveniently 1:1 to 1:50, preferably 1:4 to 1:10. The
composition is preferably used in dilutions which contain 0.05 to 5% by
weight, preferably 0.1 to 1.5% by weight, of the phosphonium compound.
1~ The invention further relates to the use of the cited quaternary
phosphoniurn compounds of formula [(C4Hg)3P Cntl2n+1]+ X- or
l(C4H9)3P CnH2n+1]2+ S042- in combination with alkali metal salts or
aliphatic C6-C12monocarboxylic acids for protecting timber against growth
by blue-stain fungi and mold fungi. The use of aqueous solutions of the
2 0 combination formulation is preferred.
The invention relates further to a process for protecting timber
against growth by blue-stain fungi and mold fungi, which comprises
treating said timber with a solution of suspension which contains the
~ua~ernary phosphonium compound of formula [(C4Hg)3P CnH2n+1]+ X~
25 or [(C4Hg)3P CnH~n+1]2+ S042-, wherein n and X- are as defined above,
and an alkali metal salt of an aliphatic C6-C12monocarboxylic acid. A
process which compris0s the use of an aqueous solution is preferred. In
the process of this invention, the timber to be protected is conveniently
impregna~ed with a solu~ion of both active ingredients. This can be done,
3 0 for example, by immersing the timber in, or spraying it, with the cited
solution or solutions.
Use Example
Tests for determining the protective action against fungal growth are
3 5 carried out using freshly sawn timber in accordance with NWPC Standard
1.4.1.3./79 (Nordic Wood Preservation Council, Mycological Testing of
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Anti-stain Prsservatives for Freshly Sawn Timber, the Mini-board Method,
Sweden 1980). A novel formulation of the following composition is used:
13.9% of a NaOH,
20.3% of a water
50.0% of 2-ethylhexanoic acid
0.8% of isopropanol and
15.0% of a ~0% solution of tributylphosphoniumtetradecyl
chloride in water.
The solutions listed in Table 1 are prepared by diluting this
concentrate (=100%) with water.
One half of test pine boards (10 x 50 x 300 mm) is immersed for 60
s0conds in each solution, dried for 24 hours and inoculated with the
following mixed cultures:
mixed culture of blue-stain fungi: Aureobasidium pullulans,
Sclerophoma pityophila,
Ceratocystis pilifera;
mixed culture of mnld fungi: Aspergillus niger,
Cladosporium herbarum,
Trichoderma viride.
2 5 The inoculated boards are incubated at roorn temperature. After 4
weeks the growth is compared on the treated and untreated sides and
evaluated according to the followirlg scale:
0 = free from fungal growth
3 0 1 = traces of growth
2 = liffle growth
3 ~ moderate growth
4 = vigorous to maximum growth
3 5 The results are reported in Table 1.
, . . .
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Table 1: Degree of fungal growth after 4 weeks. Comparison with/without
the treatment of this invention (immersion in 4.0% and 5.0%
aqueous solution of the concentrate).
_ .. _ ...... _
Percentage ofBlue-stain growth Mold growth
concentrate
untreated treated untreated treated
half half half half
., _ . . _ _ , ,_
4.0 3 0 3 0
_ ,
5.0 4 0 4 0
.. __ . __ .....
It is evident from the table that the novel formulation affords
excellent protection against growth by the rnold and blue-stain fungi
investigated in this test.
