Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to compositions containing
cuprammonium complexes of carboxylic acids and a method of
preparing such compositions~
Copper salts have long been used ln fungicidal compositions.
Furthermore, the toxicity of soluble copper salts is also well
recognised. Whilst it is possible to produce solid copper compounds
of moderate and acceptable to~icity levels, the use of such solid
compounds even in very fine form is limited to a considerable
extent due to the difficulties in applying such solids uniformly
on a substrate surface to achieve maximum surface cover for effective
protection per unit weight of the compound. Even in cases where
such copper compounds have been produced in soluble form, such
solutions have been very dilute solutions containing more than 60%
by weight of the solvent or about 8% of effective copper content.
Such compositions in the context of cuprammonium carboxylate have
been claimed and described in US patent Nos. 3900504 and 4020180.
Such solutions present a different kind of problem, i.e. that o
bulk handling which makes them commercially unviable and furthermore,
the limited solubility of these complexes generate additional
problems due to precipitation and sedimentation in the containers
used for transportation~ In commercial operations, such precipi-
tation can also Iead to blockages in pumping and spraying equipment.
It has now been found that homogeneous aqueous solutions of
cuprammonium complexes may be produced which not only contain
relatively~smaller amounts of the solvent but also have a higher
effective copper content than produced hitherto.
Aecordingly,~the present invention is a homogeneous liquid
composition ccmprislng~a cuprammonium complex of one or more Cl to
C4~monocarboxylic acids containing between 4 and 10% by welght of
30 ~ ~dissolved copper and up to 40% by weiyht of water.
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According to a further embodiment, the present invention is
also a method of preparing a homogeneous liquid composition
comprising a cuprammonium complex of one or more Cl to C4 mono-
carboxylic acids containing between 4 and 10% by weight of
dissolved copper and up to 40% by weight of water, said method
comprising reacting an acid a~nonium salt of the monocar~oxylic
acid with a copper compound selected from cuprous oxide and cupric
oxide in the presence of aqueous ammonia.
The monocarboxylic a dd moieties in the salt may be derived
from saturated or unsaturated monocarboxylic acids. Examples of
such acids include fo =ic acid, acetic acid, propionic acid, the
isomeric butyric acids, acrylic acid and methacrylic acid. By the
expression "acid ammonium salt" as used here and throughout the
specification is meant salts in which two moles of the acid moiety
are present per mole of the ammonium ion on a chemical equivalent
basis. mus~ the acid ammonium salts are preferably one or more of
ammonium di-formate, ammonium di-acetate and ammonium di-propionate.
The product of the reaction between the acid ammonium salt and the
copper oxide in the presence of aq~leous ammonia is a dark blue
aqueous solution cor~aining the cupram~nonium complex in a concen-
tration within the specified range,
The llquid compositions of the present invention possess
fungicidal activity due to the presence of copper. These compo-
sitions therefore find several uses, for example as paint biocides,
as wood preservatives, as fungicides to prevent mildew on fabrics
and to counteract growth of alg`ae and marine fouling. Particularly,
these composltions inhibit the growth of fungi such as
herbarum which are responsible for the spoilage of paints, and
Co~ which causes wood decay.
For any o~ the above uses9 the compositions may be used as such
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in the form of their aqueous solution. me aqueous solution may
however contain other conventiollal additives capable of supple-
menting their activity such as free formic acidl propionic acid,
formalin and bisulphites. The aqueous solutions may additionally
contain wetting, spreading or sticking agents or may be emulsified
with mineral oils where necessarya
The concentration of the cuprammonium complex applied to a
substrate will depend not only upon the substrate and its end use
but also on the nature of the attack to be treated or prevented~
10 m ese can however be easily ascertained by those skilled in the
art. For example, for the preservation o* wood, treatment rate
equivalent to concentrations of copper in the range On4 to 1.0%
may be used.
Where it is desirable to dilute the cuprammonium complex
solution for high volume application, as for instance in the case
of preservation of wood referred to above, the dilution is
preferably carried out using a 1~3% aqueous ammonia solution to
prevent precipitation of the comple~. I water alone is used as
diluent, for example at dilutions o about 100:1, a flocculent
20 gelatinous blue precipikate may separate.
The cuprammonium complexes of the present invention have
greater solubility in water than the conventional copper salts
such as copper formate and copper propionate, and when prepared,
have a pH of between 7 and 9~ Their improved solubility allows a
freerflow and more even spread of the composition onto the substrate,
particularly when used as epraysO As can be seen from the table,
compared to copper propionate and copper formate, the cuprammonium
complexés are ~ore water soluble which facilitates application by
spraying. The differences in copper solubility (at ambient temperature~
are presented below:
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_ %Cu in a saturated
Compound aqueous solution
~ _
Copper Propionate2.2
Cuprammonium 5 - 10 0
Propionate Complex .
Copper Formate 2O9
Cupramntonit~ 4 5
Forma~e Complex .
~_
The invention is furbher illustrated with reference to the
following ~xamples.
10 XXA~PI,155
A. PREPARATION OF COMPLEXES
The comple~ can be prepared by reaction of the acid
ammonium salt ~70% w/w aqueous solution) with either cupric or
cuprous oxide and aqteous ammonia. Some preparations are described
below.
1. A 70% aqueous solution of ammonium dipropionate (212 g) was
added to cupric oxide ~30 g), and the mixture heated tmder reflux
for 30 minutes. A~ter cooliny 88 g of aqueous amntonia (33.3% w/w
20 NH3) was added, and the mixture filtered to give a dark blue
solution containing 13.5% w~w MH3, 39~% w/w propionate, 7.~% w/w
copperj and 39.7% w/w water (pH = 8.0).
2. A 70% aqueous solution of ammonium dipropionate (106 g) was
added to cupric oxide (30 g), and the mixture heated urtder reflux
for 30 minutes. After cooling 44 g of aqueous ammonium (33O3% NH3)
was added, the solution recooled, and filtered to rentove unxeacted
cupric oxide ~6.6 g). l~te final solution contained 13.0% w/w NH39
38.2% w/w propionate~ 10% w/w copper, and 38.8% w/w water (pH -- 8~0).
30 ;3. ~ 70~ aqueous solution of amntoniu~ dipropionate (212 g) was added
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to 30 g of cuprous oxide and heated under reflux for 1 hour.
After cooling, 88 g of aqueous ammonia ~33.3%) was added, the
solution cooled, and filtered to remove excess copper metal (12 g).
The final solution contained 14.0% w~w NH3, 41~3% w/w propionate,
5~0% w/w copper9 and 39~7% w/w water tpH = 7.6).
This complex was prepared by reacting cupric oxide with
aqueous am~onia and 70% aqueous ammonium diformate. The final
solution contained 4.5% by weight copper, 40% by weight formate,
and 39.0% by weight water.
B~ ACTIVITY u~ ~IDR~MM0~lUM C[M L~3S
~c~ w~t:v~
5. The complex in solution at various dilutions was run onto
wooden blocks o Scots pine sapwood o the species
as follows: ~
The blocks were oven dried, weighed and vacuum impregnated
with a solution of cuprammon ~ propionate. Twelve (12) blocks were
treated at each of the ~ollowing concentration of the complex in
solution as % copper: 1.0, 0.637 0.40, 0~25, 0.16, 0`.10 and 0.063~
The blocks thus treated along with untreated blocks were exposed to
a culture of Cc~ r~ell~ organism in bottles containing soil
for a period of six (6) weeks.
After this period the test blocks were removed from the culture,
weighed, oven dried and reweighed~ The inal oven dried mass was
` compared with the initial dry mass to calculate the loss in mass
due to decay by the organism~ Two blocks treated at each concen-
tration and not exposed to the o~ganism were also oven dried and
weighed to~correct for the uptake of the preservative complex.
On the basis of weight loss, the toxic limit, i.e. the interval
;
~ 30 between that concentration which just permits decay and the concentration
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next highest in the series which inhibits all decay was 0.25 -
0.40% copper in the treating solution. The loading in the wood
expressed as copper for this toxic limit was 1.9 - 3.2 Kg/m of
wood.
As a further comparison one of the most widely used waterborne
preservativ~ based on copper sulphate, potassium dichromate and
arsenic pentoxide known as 'CCA preservative' was tested as before
using blocks of the sa~e wood and the same organism, This gave
a toxic limit of 1.8 - 3~0 Kg/m in terms of metal content. Thus
for a metal loading similar to that of CCA, the present invention
enables the use of the more acceptable copper complexes~
Paint Biocide Activity
6, The activity of copper ammonium propionate as a paint biocide
was evaluated as follows:
Copper = cnium propionate (500 ppm) was added to a molten
medium (50C) consisting of Czapek Dox agar (Oxid CM 97) and poured
lnto 100 mm Petri dishes and the mixture allowed to harden. Surface
moisture was removed from the growth media by drying at 50,C. The
agar plates were inoculated with suspensions of the test organisms
using a multipoint inoculator, and incubated for seven (7) days at
; 25C. A corresponding control medium without addition of the complex
was prepared, inoculated and incubated under identical conditions.
The following spore ger~ination results were obtained. In all cases
even the slightest growth or spore germination was considered to
constitute a failure of the preservative to inhibit the organisms~
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Test Organisms
Cladosporium Fusarium Penicillium Pestalotia
herbarum species expansum macrotricha
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Cuprammonium No No No No
propionate germination germination germination germination
(500 ppm)
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- Control Positi~e Positive Positive Positive
_ germination germination germination germination
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