Note: Descriptions are shown in the official language in which they were submitted.
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DETAIL13D DESCRIPTIOI\~ OF Tl~lE INVl~NTION~
Certain biocides have proven useful in various paint
formulations, such as exterior latex house paints. However,
in certain paint formulations, particularly alkyd-modified
acrylics, straight acrylics and vinyl acrylic copolymers, some
commercially available paint biocides react with certain com-
ponents in the paint formulation causing a transien~ yellow-
ing on surfaces painted with white paint. The transient yel- ;
lowing lasts up to 72 hours and is totally unacceptable in
the paint industry. The present invention provides a method
for overcoming the undesirable problem by incorporating a
phenyl-mercury salt into the paint formulation containing
specified biocides.
In recent years, a new series of biocides have been
developed and found use in many industrial applications. They
are the diiodomethylsulfones, carrying alkyl, aryl, aralkyl,
haloalkyl, nitroalkyl, nitrophenyl, halophenyl and halonitro-
phenyl substituents on the sulfone moiety. While these bio-
cides are highly effective in many indus~rial environments,
they were acceptable in the paint industry only to the ex-
tent of dark paints, because they develop a transient yello~-
ing on white and other light-colored paints. Although this
color disappears after 2 or 3 days, the yellowing effect is
totally unacceptable for exterior paints. Since biocides are
primarily used in exterior paints, the temporary discoloring
effect caused by them essentially removed the above biocides
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from use in paints.
I~ has now been found that a paint composition con-
taining a diiodomethyl sulfone (DIS) biocide of the formula
R~SO2CHI2 wherein R is phenyl, alkylphenyl, dialkylphenyl,
benzyl, chlorobenzyl, dichlorobenzyl, or an alkyl group of
2-8 carbon atoms, hereinafter referred to as R-DIS is sub-
stantially completely prevented from yellowing by the addition
of an acyloxy phenylmercury salt in an amount from 25 to 500%
of the amount of said biocide. The term "acyloxy phenylmer-
cury salt" is intended to include those PM salts which are
derived from organic mono- or dicarboxylic acids which may
include a double bond in those instances where a carbon chain
of more than 10 carbon atoms is involved. Typical representatives
are phenylmercury acetate, phenylmercury oleate, di-(phenyl-
mercury) dodecenyl succinate and other salts of this general
nature. These salts can be expressed by the formula R'-COOHgC6H5
or R"-(COOHgC6H5)2 wherein R' is an alkyl chain of 1-19 and R"
is an alkylene chain of 2-18 carbon atoms, preferably contain-
ing no more than one double-bond. These PM salts are effective
in preventing yellowing whether the above DIS is used alone or
together with a diluent as it is customary to dilute biocides
of this type with 25-100% of a biologically inert material.
Often, such a diluent consists of butylated hydroxytoluenes,
hereinafter referred to as BHT.
In a general embodiment of the present invention, a
paint composition is made up accor~ing to known and well ac-
cepted formulations except that, as the biocide, between 1 and
5 pounds of the above biocide per 100 gallon of paint
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~ormulation and an amount equal to 25-500% of said biocide
amount of the above acyloxy phenylmercury salt are added. Such
a paint formulation is stable to normal storage for extended
periods of time and upon use thereof for coating outside sur-
faces, substantially no yellowing effect can be detected.
In order to illustrate the improvement attained by
the present invention, reference is made to the following
examples which, however, are not intended to limit the in-
vention in any respect.
EXAMPLE 1
White paint formulations were made up with the fol-
lowing ingredients:
Water 175 lbs.
Anionic surfactant 10 5 "
Non-ionic surfactant 2 5 "
Dispersing Agent 1.5 "
Defoamers 3.0 "
Ethylene glycol 25.0 "
Hydroxyethylcellulose 2.1 "
Titanium dioxide 237.5 "
Magnesium silicate 191.4 "
These ingredients, together with the biocides listed
below, were dispersed for 20 minutes at hiyh speed and then
combined with a mixture of
Acrylic emulsion 490.8 lbs.
Tributyl phosphate 5.0 "
Defoamer 1.0 "
Ammonia 2.0 "
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Ten separat~ formulations were made up containing
the biocide combinations a) to e) shown helow. Fi~e of these
were taken from the above paint mixture (A); the other five
contained the same mixture except for using a different acrylic
emulsion (B). All listed ingredients were selected from those
used in standard commercial paint formulations.
a) 4 lbs. R DIS/BHT 4:1
b) 4 lbs. R-DIS/BHT 4:1 + 1.0 lb CH3COOH C6H
c) 4 lbs. R-DIS/BHT 4:1 ~ 2.0 lbs " g
- d) 4 lbs. R-DIS/BHT 4:1 ~ 3.0 lbs "
e) No additive
R= p-tolyl
Three-mil drawdowns of the ten coatings were prepared,
using a 3-mil bird blade on sealed charts. The charts were
then placed under UV sunlamps and the yellowing index of the
films was determined instrumentally, using a Hunter Color Dif-
ference meter after exposures of 24, 48, 72, 96 and 168 hrs.
The yellowing index numbers are show~ in Table I (higher number
indicates increased yellowness).
T BLE l
Paint-Biocide 24 hrs. 48 hrs. 72 hrs. 96 hrs. 168 hrs~
A ~ a 13.0 16.1 19.0 19.820.3
A - b 2.1 7.0 10.4 13.918.7
A - c 1.0 1.3 1.7 5.013~2
A - d 1.0 1.3 1.3 2.1 3.2
A - e 0.7 1.0 1.0 1.0 1.2
B - a 6.3 7.5 8.3 9.610.3
B - b 1.1 1.7 1.9 2.0 2.6
B - c 1.0 1.5 1.5 1.5 1.4
B - d 0.9 1.3 1.3 1.4 1.4
B - e 1.0 1.4 1.6 1.6 1.2
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EXAMPLE 2
.
The above ten formula~:ions were also applied to
panels of white pine by brushing them on in two coats at a
spreading rate of 400 ft2/gal. These panels were then exposed
to direct sunlight for 10 days and the yellowness index was re-
corded by 1:he apparatus of Example 1 at periodic intervals as
shown in Table II.
TABLE II
;:
Paint-Biocide 8 hrs. 16 hrs. 24 hrs. 54 hrs. 102 hrs. 200 hrs. 240 hrs.
A- a10.3 11.1 11.4 4.03.9 5.7 5.9
A - b2.2 5.3 6.0 2.94.0 5.3 4.4
A- c 1.8 2.5 2.8 2.03.9 4.1 3.6
A - d2.1 3.2 2.5 1.84.0 4.2 4.3
A - e1.6 2.6 2.2 1.53.5 3.7 3.6
B - a3.1 5.5 6.4 3.34.5 5.7 5.1
B - b1.7 3.0 3.2 2.54.6 4.8 4.0
B - c2.2 2.9 3.1 1.94.5 4.5 3.9
B - d2.0 2.9 2.9 1.84.7 4.4 3.9
B - e2 1 3.4 3.2 1.84.6 4.6 4.1
EXAMPLE 3
Another paint formulation was prepared from the follow~
ing ingredients:
Water 250 lbs.
Anionic surfactant 8.0 "
Non-ionic surfactant2.5 "
Dispersing agent 1.0 "
Hydroxyethylcellulose2.5 "
Ethylene glycol 25.0 "
. 2-Ethoxyethanol acetate 15.0 "
Defoamers 3.0 "
Titanium dioxide 250.0
Magnesium silicate200.0 "
Biocides as shown below
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After mixing these components at high speed for
20 minutes, 400 lbs. of vinyl acrylic emulsion containing
1.0 lb. of a defoamer were blended with the above. The vinyl-
acrylic paint so obtained was tested as shown in Example 2.
The yellowing index results are given in Table III, using the
same biocide mixtures a) to e) shown in Example I.
TABLE III
Biocide 8 hrs. 24 hrs. 48 hrs. 96 hrs. 2~0 hrs.
_ ._ _ . . _ . .. . ... _ _ .
a 1.85.2 5.3 6.8 7.7
b 1.22.5 3.8 4.7 3.7
c 1.63.0 4.6 4.8 4.2
d 1.52.8 3.9 3.9 3.8
e 1.32.9 4.1 4.0 3.8
... ..
By replacing the above 80% R-DIS/BHT mixture with a
50% mixture or pure 4-tolyl diiodomethyl sulfone in the above
formulations, results substantially identical to those in Table
III are obtained.
EXAMPLES 4-27
A paint base was made up by a 20 minute high-speed
dispersion of
Water 215.9 lbs.
Anionic surfactant 10.5
Non-ionic surfactant 2.5 "
Dispersing agent 1.5 "
Defoamers 3.0 "
Ethylene glycol 25.0 "
~Iydroxyethylcellulose2.3 "
Titanium dioxide 237.5 "
Magnesium silicate 237.5 "
Biocide mixture as listed
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This dispersion was blended with a mixture of
Acrylic emulsion 390.8 lbs.
Long oil alkyd 30.8
Cobalt drier 0.2 "
Zirconium drier 0.6 "
Defoamer 1,0 "
Tributylphosphate 9.3 "
Ammonia 1.Q "
The results obtained with this latex house paint con-
taining phenylmercury acetate (PMA) or di-(phenylmercurydodecenyl-
succinate)(PMDS) according to the tests in Example 1 (A) and
Example 2 (B) are shown in Table IV. In all instances, the DIS
of Example 1 was used as a mixture with butylated hydroxy-
toluene containing 80% by weight of DIS. Those skilled in the
- interpretation of color index differentiating measuring devices
such as the above will recognize that the yellowing rates of
1 and 3 would not be distinguishable by the human eye. Thus,
a reading of about 3 is still acceptable in a white paint.
Table IV also contains a mold rating (MR) column which
shown, on a scale from 0 (no mold) to 4 the performance of the
paint in a mold box test. In this test, the above paints were
applied to tongue depressors by dipping the latter in the paint,
J drying the, inoculating them with a mixture of A. pullulans,
P.funiculosum and A.niger and placing them in mold boxes for four
weeks at 32C and a relative humidity of 90-100%. The MR-read-
ings given below are those obtained after 4 weeks.
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TABLE IV
,
Additives in lbs. Test A Test B
Ex.# per 100 gal.paint ~4 96 8 54 240 hrsMR
__
4 9 PMA 2.4 3.0 0.7 1.6 3.1 2
5 ~I 2.4 ~.8 1.2 1.8 3.8 3
6 1 " 2.3 2.7 1.2 1.5 3.7 4
7 7 " + 1 DIS 1.5 2.0 1.0 1.5 3.7
8 5 " + 1 " - 1.9 3.0 1.0 1.4 3.9 1
9 3 " + 1 " 1.3 1.9 1.2 1.5 3.4 0
1010 1 " + 1 " 1.3 2.1 1.4 1.6 3.9
11 7 " + 2 " 1.3 2.3 1.4 1.8 5.0 0
12 5 " +2 " 1.2 2.2 1.1 1.7 4.4 0
13 3 " + 2 " 1.1 2.5 1.9 1.8 4.4 0
14 1 " + 2 " 1.2 3.0 1.5 1.8 4.4 0
. . ..... _ _
9PMDS 1.4 2.1 1.6 2.2 3.4
16 5 " 1.5 2.1 1.7 2.0 3.4 3
17 1 " 1.4 1.9 1.7 1.8 3.9 4
18 7 " + 1 DIS 1.4 2.0 1.7 1.7 3.6 0
19 5 " + 1 " 1.2 2.0 2.1 2.0 4.1 0
2020 3 " + 1 " 1.1 2.1 1.6 1.7 3.6 0
21 1 " + 1 " 1.6 3.0 1.8 1.9 3.8 0
22 7 " + 2 " 1.4 2.6 1.9 1.7 3.9
23 5 " + 2 " 1.5 4.3 1.4 1.7 3 5 0
24 3 " + 2 " 1.0 4.9 1.7 1.9 4 1 0
1 " + 2 " 1.4 4.9 1.8 2.2 4.3 0
. . .. _._ .
26 2 DIS 7.8 9.6 5.7 2.5 4.6 0
27 none 1.7 2.2 2.4 2.5 3.4 4
. .
The above examples clearly show that a house paint
containing no biocide deteriorates rapidly when exposed to com-
30 mon molds and that it therefore requires biocidal protection.
As shown, a DIS alone provides excellent protection, but it is
unacceptable from the discoloration standpoint. However, a
combination of a DIS with a phenylmercury salt of an organic mono-
or dicarboxylic acid protects the palnt against fungal growth
and against discoloration by sun light or UV light.
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EXAMPLES 28-32
The above examples all demonstrate the use of a
specific DIS, namely the 4-tolyl diiodomethyl sulfone. In the
following table, yellowing results are shown with paint formu- -
lation drawdowns containing a DIS other than the above. In
all instances, the paint formulation and preparation of
Example 1 is used. Substituent R shown in Table V refers to
R of the above R-DIS, and the measured yellowing index (YI).
In each example, the paint contains 4 lbs. of a DIS with (b)
or without (a) and 3 lbs. of phenyl mercury acetate per
100 gallons of paint.
TABLE V
R YI after 24 hrs. YI after 48 hrs.
28 et~h~yl b 160 9 21 9
29 hexyl a 17.6 23.4
~ b 0.8 2.0
.. . _ _ _ . .. _ . . .. _ . _ _ _ . _ _ .
Cl---- b __ 0 8 _ 1 6
31Cl ~ CH2- a 10:8 0 9
32 ~ CH2- a 10:8 0 9
.._ . ................ . _ . . . _ . . _ . _
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EXAMPLE 33
While the above examples use the R-DIS as an 80%
mixture with BHT, the same results are obtained when sub-
stantially pure R-DIS is used:
The paint formulation of Example 1, emulsion B, is
prepared as stated, but containing 4 pounds of tolyl-DIS and 3
pounds of phenylmercury acetate per lOQ gallons of paint.
This paint, with and without said mercury salt, was tested
exactly as shown in Example 1, resulting in a yellowing index
reading of 1.6 for the sample containing biocide and mercury
salt and 4.8 for the sample containing the biocide alone, after
48 hours under UV light.
While the above examples demonstrate the effects with
only two particular phenylmercury salts, other acyloxy phenyl-
mercury salts or diacyloxy diphenylmercury salts produce sub-
stantially similar results. These salts have been used before
by the paint industry and are well known and easily synthesized.
However, their use to prevent the temporary yellowing caused
by the use of a DIS as the biocide was a surprising and un-
expected discovery.
Paint compositions containing a DIS and the above mer-
curial salt are substantially completely protected against bio-
logical or light degradation. The preferred range for a DIS is
between 2 and 4 lbs. per 100 gallons of paint with 2 to 5 lbs.
per 100 gallons of said phenylmercury salt. While ordinarily, 5
lbs. of a DIS is the practical upper limit in 100 gallons of paint,
larger amounts can sometimes be usefully employed, although
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amounts of >10 lbs/100 gallons serve no additional purpose.
Mercury salt amounts of 25~ of the amount of the bio-
cide is about the lowest level that wilI prevent yellowing
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caused by the biocide. Amounts up to 5 times the amount of
the biocide can be used but on a weight basis, it would be
unnecessary to exceed 10 lbs/100 gallons of paint. In some
paint systems, particularly those used for interior paints in
dry climates, 1 lb/100 gal. of the biocide produces sufficient
protection against biological deterioration of the paint or its
substrate and 0.25 lb/100 gal. of the acyloxy phenylmercury
compound would be sufficient to overcome the temporary yellow-
ing effect that might occur with this low level of a DIS. On
the other hand, in paints designed for exterior use in humid
climates, 5 lbs. of a DIS and 10 lbs. of the phenylmercury salt
produce substantially full protection against biological and
light deterioration or degradation. Larger amounts of either
additive could be used but provide no significant benefit over
the named amounts.
Aside from the mercury salts exemplified above, phenyl-
mercury oleate provides the same excellent results as demon-
strated in the examples. However, other acyloxy phenylmercury
salts can be used in the same fashion, i.e. the phenylmercury
propionate, hexanoate, decanoate, palmitate, stearate, or the
di(phenylmercury)maleate, Malonate, succinate which may carry
alkyl substituents in the alkylene chain between the carboxy
groups.
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