Note: Descriptions are shown in the official language in which they were submitted.
1~3937
MICROBIOCIDAI, AGENT-CONTAININ~ CELLULOSIC AND PLASTICS
Background and Prior Art
This invention relates to the protection of plactics, polymeric
materials, and cellulosic materials against attack by microorganisn~s~
Synthetic, filmrforming materials such as those used in the
manufacture of plastic or polymeric films, and various types of plastics
or polymers, are known to be subject to attack by microorganisms. Such
microorganisms include kacteria, fungi and actinomycetes. The last men-
tioned are microorganisms found in soil which contain no chloroFhyll.
They are usually classified with the bacteria, but resemble both bacteria
and fungi; they are intermediate in size between fungi and bacteria.
Such microorganisms attack plastics and polymers and can cause
damage or deterioration ranging from discoloration and staining to
embrittlement or actual disintegration, depending on the type of plastic
or polymer, and the environment in which it is situated. Severe damage
can be produced to plastics or polymers which are utilized in certain
environments, such as those with high humidity. Plastics and polymers
are commonly used for instance, in underground construction, in pipes and
conduits, cables, sheathing, insulation, etc. In such an environment,
they are subject to severe deterioration by soil-borne microorganisms.
Similarly, plastics and polymers used in materials such as swimming pcol
liners, awn mgs, camping equipment, and other articles for outdoor use,
and in upholstery, car tops, shoes, boots and clothing, in which they may
be exposed to natural humidity and/or sweat, possibly in ccmbination with
somewhat elevated temperatures, are subject to microbial detexioration.
In addition to physical deterioration of plastics and polymers,
mieroorganisms gxowing on the surface of such materials can cause dis-
coloration and/or staining thereof resulting in a shortening of the use-
ful life of said materials for at least aesthetic purposes. Actinomy-
cetes, in particular, growing on the surfaces of plasties and polymers
can produce colored byproduct dyes which are soluble in the pla æicizers
. .
.: .
3~3'7
used in such substances, and which migrate through the substance via the
plasticizer, resulting in the phenomenon know as pin staining." In
addition, surface growth of microroganisrns on polymers may interfere with
junctional performance, for instance when used as lubricating surfaces.
In order to prevent attack and deterioration or discoloration
of polymeric or plastic materials by microorganisms, a lumber of corn-
pounds have been used as industrial biocides.
For use as a biocide in connection with plastlcs and polymers
a compound must have the following properties:
effectiveness at low levels against many microoganisms;
compatibility with plasticizers and other chernicals used in the
formulation ox plastic and polymeric products;
lack of a disadvantageous color or odor;
resistance to leaching from plastic or polymeric materials;
and particularly;
a) thermal stability at temperatures over 300F. (148C.)so
that deterioration of the biocide does not occur during
- the processing of plastics and polymers;
b) mobi1ity - the ability to migrate through the plastic,
polymer or plasticizer utilized therein, so as to be dis-
sipated therethrough; and
c) stabillty towards ultraviolet and other light radiation.
.
Such properties are necessary for plastics and polymers which
are cast, rolled, molded, extruded, or otherwise fabricated into a con-
tinuous ion for use in variolls ways such as raw materials for the manu-
facture of plastic or polymer articles or as plastic or polymeric
coatings, as well as plastics and polymers which are knitted or woven
into continuous fibera.
Similarly, cellulosic materials, such as cotton and other
fibers are subject to damage or deterioration by mlcroorganisms; indus-
trial biocides have been used to protect such materials and articles
formed Fran them Fran microbial deterloration. Properties such as
3~7
stability toward ultraviolet light and heat are also required of biocides
for such materials.
Both the prevention of growth in the contact area, that is on
the material itself, and inhibition of growth in a ~n~ surrounding the
contact area, are of importance in order to prevent the spread of an
actively growinO organism. The biocide must possess a positive anti-
microbial actlvity in a zonk of inhibition surrounding the article;
otherwise, a compound which is effective as a biocide in the contact area
itself would nevertheless not control heavy growth on the surface or on
substances associated with or attached to the material. Such property is
important, for instance, for fabrics in which a polymeric fiber, such as
a polyester or polyamide, is laminated to a cotton or other cellulosic
backing such as canvas.
Many of the industrial biocides currently used in connection
with plastics, polymers and cellulosic fibers are organometallics. these
compounds are effective in preventing microbial attack on such materials.
However, such compounds may be suspect for reasons of toxlcity or envi-
ronmental effect and problems caused by their handling and are now less
accepted in sore Or the industrial uses in which they have hitherto been
employed. It has thus become desirable to wind new, non-metallic bio-
cides for use with such materials.
Summary of the Invention
In brief, this invention comprises a method of protecting a
cellulosic, plastic or film-formlng polymeric composition, fabricated
into a continuous form, comprising incorporating into such composition or
form a microbiocidally effective amount of a compound having the formula
l 12
02C -== CN
Yn
in which Y is hydrogen, Cl-C4 alkyl, or halogen; Rl and
R2 are independently hydrogen or methyl; and n is 1 or 2. Additionally,
this invention relates to such compositions containing or coated with a
microbiocidally effective amount of such a compound.
35~3~
The term "film-form~ng" is meant to refer to polymeric parti-
cles, whether present as dry particulate matter, or in liquid, dissolved,
suspended, continuous, or any other form, particularly including the
ultimate for for which such particles are designedO The term "plastic"
is similarly intended to be regarded as a broad term and is to be under-
stood to include polymeric materials which can be cast, extruded, in~ec-
tion molded, or compression molded into a desired state.
Certain polymers such as alkyd resins, polyester based ure-
thanes, polyesters, and certain cellulosic polymers such as benzyl-,
methyl-, hydroxyethyl-, and sodium carboxymethyl-cellulose, are suscepti-
ble in and of themselves to attack by microorganisms. Other polymers
such as polyethylene and polystyrene may become susceptible after degra-
dation through prolonged weathering. Still other plastics and polymers,
such as polyvinyl chloride, are considered in and of themselves to be
generally resistant to such attack. However, many substances utilized
with polymers to produce polymer1c or plastic products for instance,
flexible polyvinyl chloride sheeting, contain additives such as plasti-
clefs stabilizers, fillers, lubricants, thickening agents or starch
sizings for synthetic fibers, which are susceptible to attack by micro-
organisms. must plastics or other materials formulated from a polymerresistant to such attack but incorporating a substance such as a plasti-
cizer, which is susceptible to such attack, are thereby rendered suscep-
tible to deterloration, discoloration, and other damage from microorgan-
lsms. Alternatively, microorganlsms can grown on debris,~lubricants, or
2~ other materials adhering to the surface of a non-susceptible plastic or
polymer. Metabolic products ox such organisms may cause etching of the
substrate material.
The compounds which have been found to be biocides or use with
cellulosic materials, plastics and polymers are those having the formula
Rl ~R~
02C - CCN
I, J
n
30 in which Y is hydrogen, Cl~C~ alkyl or halogen; Rl and
R2 are independently hydrogen or met~lyl; and n is 1 or 2. Preferably the
3~3~
group Y is located para to the sulfonyl moiety. The term "halogen"
includes chloro, bromo, iodo and fluoro, and preferably indicates chloro,
bromo, or fluoro. The most preferred compound is that in which Y is
p-methyl. Other preferred compounds are those in which Y is p-chloro,
p-fluoro, p methoxy or hydrogen. These compounds.
are disclosed in U.S. Patents 3,159,532 and 39159?666
of Heininger, et al., as part of a series of aryl sulfonyl aIkene nit-
riles. As shown in those patents, these compounds are effective micro-
biocides for use in agricultural environments, particularly as soil
microbiocides, and showed activity in vitro against a number of fungi and
bacteria. Also mentioned with respect to the p-~.ethyl compour.d is soap
bacteriostatic and paint preservative activity. No mention is made in
these patents of any utility with respect to plastics, polymers, or
cellulosic fibers.
or use as an agricultural biocide, compounds must possess a
necessary short term, ephemeral activity, as agricultural biocides must
not leave residues in either the soil or the plants which have been
treated. Ihe properties necessary for use as a plastic, polymer or
cellulosic material biocide are different, however, from whose required
or effectiveness of an agricultural biocide. As pointed out above,
particularly for use as plastics or polymer biocides, compounds must
possess high thermal stability, ultraviolet radiation stability, and the
ability to migrate through the plastic. Such properties are not neces-
sarily possessed by compounds which are soil fungicidesg nor are suchproperties required of, or necessarily possessed by compounds which are
used as biocides for soap and for preservatlon of paint.
m e compounds to which the present invention relates have been
found to possess surprisingly high thermal stability, with the p-nethyl
compound being thermally stable at 250C. They hove been found to possess
the necessary, unexpected ability to mlgrate through plastics, an the
requisite, surprisingly high stability to ultraviolet radiation
The compounds nay be prepared according to any
of several processes described in the literature, for instance in U.S.
Patents 3,159,666 and 3,541,119.
3~3~
Tests were performed on a number of compounds falling within
the generic class defined by the formula given above. These compounds
are described in Table 1.
J
~2~
TABLE 1
~S02CH=CHCN
Yn~
Yn
1 4-CH3
2 4-Cl
3 4-sec.C4~g
4 4_~
H
= 6 2,5-C1
To determine the suitability of the compounds as biocides for
these materials, tests were performed as described below.
A) ermal Stabillty
- Compound 1 was tested for thermal stability using a Perkin-Elmer DSG-2 differential scanning calorimeter. Samples ox solid conpound
weighing between 5 and 20 mg were sealed into stainless steel pans and
heated at a rate of 5.0C./minO prom 40C. to 250C. Thermogr~ns of the
compound's physical state were plotted against change in temperature. All
;~ showed approxlmately the same properties: a small endothermic transition
occurring at about 75C. and melting at between about 125-135C. Over the
entlre range tested, up to 250C.~ there was no evidence of any unusual
thermal ins~abllity.
B. Microbial Resis ance Screening Test (plastics~polymers)
:
Com~und 1 was utilized in this test. A dry powdered blend of
I; polyvinyl chloride was prepared by dry mixing of the f`ollowing ingredi-
vents (by weight): 100 parts Dla 450 polyvinyl chlorlde resln (Diamond
Shamrock Chemical Corporation), 40 parts dioctyl ph~hala~e plasticizer,
3.50 parts Mark KCB cadmium-barium~zinc heat stabilizer/~lubricant, 1.50
parts Mark C organic phosphlte heat stabilizer/lubrlcant (Mark chemicals
available prom Argus Chemical Divlsion, Witco Chemical C0~)9 0.25 parts
stearic acid and 7.6 parts epoxidized soybean oil (plasticizer/stabili-
zer). Ihis composition was then fluxed on hot rollers it 320F. (160C.)
,
-:: * Trademark
until homoger.eously blended. Then a sufficient quantity of solid Com-
pound 1 was added, to provide a composition containing 1.0% weight of
this compound. The composition was further milled for ten minutes, at
this temperature, then sheeted off as a film.
Samples of the film thus prepared were submitted to 100 hours
of exposure treatment, in a xenon arc type weatherometer (weather- simu-
lating exposure test apparatus) programmed for continuous light with 18
minutes of waxer spray every two hours. The exposure was conducted
according to ASTM Standard G26-70.
Prior to exposure, and after 100 hours of exposure, samples of
the films containing the test compound were tested for antimicrobial
effect by the following procedure: Tne samples were placed on a nutrient
agar inoculated with the test organism. Those samples inoculated with
bacteria or actinomycetes were incubated for 24 hours at 37C.I samples
inoculated with fungi were incubated 14 days at 28C. After the incuba-
tion period the anti-mlcrobial activity was evaluated by measuring (in
millimeters) the size ox the clear zone of no growth around the sample
and rating the degree of growth or stain visually.
The organisms utilized in the tests were:
BACTERIA
.
Staphylococcus aureus
Klebsiella pneumoniae
Pseudomonas aeruginosa
.
Bacillus~subtilus
ACTINOMYCEIES
.
Stv. recticulum
pink staining organism)
NGI: A mixed ~ungal spore suspension of:
llus
Aspergillus flavus
Penicillium funiculosum
Chaetomium glob sum ATCC 6205
the results of these tests are shown in the following Table II.
TABLE II
(ZONE OF INHI3ITION, r~M~GROWlH OR STAIN IN CONTACT AREA)
Stash. K. Pseud. Bac. Pink Mixed
aureus pneum. aer. Subt. Stain Fungi
Unexposed lO/N 4~N O/GlO/N 7/NS l~2/N
100 hrs. exposure 9/N 3/N O/G 9/G 6/NS O/N
N - no growth in contact area
G - growth in contact area
NS - no stain
C). Anti-microbial Screen~ns Tests with Ultraviolet_and Weather
Exposure (plastics/polymers)
Dry blends of polyvinyl chloride were prepared as in the previ-
ous tests with the exception that no epoxidized soybean oil was included.
To one set of blends there ~7as additionally added one part Mark 202A ben-
zophenone ultraviolet light stabilizer. Ihus, one set of blendscontained an ultraviolet stabilizer, while the other set of blends was
not stabilized against ultraviolet radiation.
he compounds ln Table I above were incorporated into ultravio-
let-stabilized and unstabilized polymer blends at levels of 0.5 and l.Q
weight % based on the polymerO lhe polymer was then milled into films
or ten minutes a about 320F. (160C.) using hot rollers.
Films were then exposed in the weatherometer as in the previous
test, for lOO and 300 hours of exposure.
:
Unexposed filn, and film which had been exposed to the weather
simulation for lOO and 300 hours, respectively, were tested for anti-
microbial activity as follows;
3~3~7
a) Samples of film which had been unexposed, exposed for 100
hours, and exposed for 300 hours were placed on samples ox nutrient agar
variously inoculated with bacteria, actinomycetes or fungi. The organ-
isms were:
BACTERIA:
5 Staphylococcus aureus ATCC 6538 (gram~positive)
Klebsiella pneumoniae ATCC 4352
ACTINOMYCEIES
S reticulum ATCC 25607 (pink staining organisn)
FUNGI: a mixed fungal spore suspension of:
As~ergillus nicer ATCC 9642
Aspergillus rlavus ATCC 9643
_nicillium funiculosum ATCC 96114
Chaetomium globo um ATCC 6205
The samples inoculated with bacteria or actinomycetes were incubated or
24 hours at 37C.; those containing fungi were incubated for 14 days at
28C. After incubation, activity was evaluated by measuring the size of
- 15 a clear zone of no growth (i.e., zone ox inhibition) around each sample
and visually rating the degree of fungal growth or stain on the sample.
: :
b) A second series of fungicidal tests was conducted using
similar samples placed on agar containing non-nutrient mineral salts and
inoculated with a mixed ~ungal spore suspension ox: Aspergillus niger,
ATCC g642, Penicillin fun1cu1osum, ATCC 9644, Chaeto=1wm globosum, ATCC
6205, Aureobasidium pullulans, AICC 9348, and Trichoderna I, ATCC g645.
The samples were incubated for 21 days at 28C. (ASIM Standard method G.
21-7~). Antifungal activity was evaluated by vlsually rating the degree
of fungal growth cn the samples.
Ihe results of these tests are contained in the following Table
,
:
3~3'7
The samples were also visually ex2mined or coloration, prior
to exposure and aster 100 hours of exposure. The results are contained
in the follow-lng Table IV.
TABLE III
Zone of Inhibition, m~/~rowth or staini_g
Com. Stabi- Wt. Exposure, Staph. K. Stv. Mixed Mixed
No. lized % hrs. aureus pneum. ret. fungi (a) fungi (b)l
1 - 0.5 0 11/N 3/N 7~NS 2/N N
- 0.5 100 loon 2/N 5/NS 0-2/N N
- O.5 300 7/N l/N 4/NS 0/N T
+ 0.5 0 ll/N 3/N 6/NS 3/N N
* 0.5 100 10/N 2.5/N 5/NS 2/N N
+ O.5 300 9/N 1.5/N 5/NS 0/N N
- 1.O 0 15/N 6.5/N 10/NS 4/N N
_ 1.0 100 13/N 5/N 7/NS 3/N N
- 1~O 300 10/N 4/N 6/NS 2/N N
+ 1.0 0 15/N 6/N 9/NS 5/N N
1.O 100 13/N 5/N 7/NS 4/N N
+ 1.0 300 10/N 4/N 7/NS 2/N N
2 + 0.5 0 ll/N 3/N 6/NS 3/N N
+ O.5 100 10/N 2.5/N 5/NS 2/N N
+ O.5 300 9/N 1.5/N 5/NS 2/N N
+ 1.O 100 10/N 3/N8.5/NS 0-1/NS N
+ 1.O 100 10/N 2/N 6/NS 0/N N
+ 1.0 300 6/N 1.5/N 6/NS 0/N T
3 O.5 0 4/N 0/G3.5/NS 0/T L
+ 0.5 100 4/N 0/G 2/NS 0/T L
+ O.5 300 3.5/M -2.5/NS 0/T L
+ 1.0 0 5/N 0/G 5/NS 0/T T
+ 1.O 100 5/N 0/G 3/MS our T
+ 13 0300 5/N _ 4/MS 0/T T
4 - 0.5 0 9/N 6/N 9/MS 0/N N
- O.5 100 8/M 2.5~N 6/NS our N
_ 0.5 300 5/N l/N 5/NS 0/T T
O.5 0 ll/M 6/N 9/NS 0/N N
+ O.5 100 9/N 4/N 7/NS 0/N N
+ O.5 300 5/N l/N 5/NS o/N T
- 1.0 o 12/N 6/N 9~iS 0/N N
- 1.0 100 10/N 5/N 6/MS 0/T N
- 1.0 300 8/N 2/M 4/NS 0/T T
1.0 0 12/M 8/N 10/NS 0/N N
+ 1.0 100 ll/N 6/M 7/NS 0/N M
+ 1.0 300 8/N 3/N 4/NS 0/N N
- 0.5 0 14/N 9/N 10/NS l/N N
- O.5 100 13/N 8/N 10/MS 0/N N
- 0.5 300 10/N 4/N 8/NS 0/N N
5 0 13/N 10/N ll/N~ 0-1/N N
3 13 3 7
T.ABLE III (continued)
Zone of Inhibition, ~m/~ro~th or staini.
Com. Stabi- Wt. Exposure, Staph. K. Stv. Mixed Mixed
No. lized ~0 hrs._ aureus pneum. ret. fungi (a) fungi ~b)l
+ O.5100 13/N 9/N 9~NS O- VN N
+ 0.5300 9/N 4/N 4/NS O-l/N N
1.0 0 l9/N 13/N 14/NS 8~N N
_ 1.0100 14/N 10/N 10/NS 5/N N
- 1.0300 12/N 6/N loons 4/N N
+ 1.0 0 19/N 13/N 17/NS 9/N N
+ 1.0100 16/N 12/N 12/NS 4~N N
-t 1.0300 12/N 7/N 9/NS 3/N N
+ O.5 0 13~N 10/N ll/NSO-l/N N
+ 0.5100 13/N 9/N 9/NS O-1/N N
+ 0.5300 9/N 4/N 4/NS O-VN N
- 1.0 0 19/N 13/N 14/NS 8/N
_ 1.O100 14/N 10/N 10/NS 5/N N
- 1.0300 12/N 6/N 10/NS 4/N N
+ 1.0 0 19/N 13/N 17/NS 9/N N
+ 1.0100 16/N 12/N 12/NS 4/N N
+ 1.0300 12/N 7~N 9/~lS 3/N N
6 + 0.5 0 9/N 2/N 4/NS O-l~N N
+ 0.5100 8/N 2/N 4/NS O-l/N N
0.5300 6/N 1/N 4/NS O-l/N N
+ 1~0 0 12/N 3/N 11/NS 3/N N
+ 1.0100 9.5/N 2.5/N 8/NS 3/N N
t 1 . 0 300 7/N l 7~NS 3/N N
:~
: I: Con- + O O O/G O/G OWNS O/HG HG
trol + O 100 O/G O/G OtNS O/Hri HG
+ 300 O/G O/G O/NS O/HG HG
: - O O O/G O/G O/NS O/HG HG
- O 100 O/G O/G O/NS O/HG HG
- O 300 O/G O/G O/TS O~HG HG
33
13
KEY TO TA~L~ III
Key: N - No growth in contact area
T - Trace growth in contact area (less than 10%)
L - Light growth in contact area (10-30~)
G - Growth in contact area (30-60%)
HG - Heavy growth in contact are (>60%)
NS No staining in contact area
TS - Trace of staining in contact area
+ - U.V. stabilizer included
- - no U.V. stabilizer
TABLE IV
Color
Compound Wt. U.V. Stabilized No exposure 100 hrs. exposure
1 0.5 - C C
1.0 - C C
0.5 + C C
1.0 + C C
2 0.5 + C C
1.0 + C C
3 0.5 + T Lt. T
1.0 + Dk. T Lt. T
Key: + - U.V. Stabilizer included
- - U.V. Stabiliæer not included
C - Colorless
T - Tan
Lt. Light
Dk~ - Dark
Thus, formulations including Compounds 1 and 2 were highly
stable toward ultraviolet radiation, as demonstrated by the fact that
films containing these compounds did not become colored after exposure to
ultraviolet light for 100 hours. With respect to Compound 1, stability
towards such radiation existed even ln the absence ox an ultraviolet
stabilizer in the formulation Such stability towards ultraviolet radi-
; ation would not have been expected from the structure ox these compounds.
All the compounds contain an activated double bond, which would be
expected to be oxidized in the presence of ultraviolet light and air.
, .
D) Long-term Exposure Test.
lQ Compound 1 was utilized in this test. A dry powdered blend of
polyvinyl chloride was prepared by dry mixing of the hollowing ingredi-
ents (by weight: 100 parts Dlamond Shamrock 450 polyvinyl chloride
37
resin, 40 parts dioctyl phthalate plasticizer, 3.50 parts Mark KCB
barium cadmium-zinc heat stabilizer/lubricant, 1.5 parts Mark C organic
phosphite heat stabilizer/lubricant, l.0 part Mark 202A benzophenone
ultraviolet stabilizer, 0.25 parts stearic acid and 7.6 parts epoxidized
soybean oil (plasticizer/stabilizer). Compound 1 was added to samples of
this blend in amounts so as to provide compositions containing 0.065,
0.25 and 1.0% by weight of this compound. the compositions were further
mixed for ten minutes, then milled into a film on hot rollers at 320F.
(160C.).
Samples of the firms thus produced were placed out-of-doors at
a location in Puerto Rico and exposed to the weather for 8-12 months,
continuously. Visual evaluations of microbial growth on the surface of
the films were made using a scale of from 0 to 5, with 0 representing no
growth visible to the naked eye and 5 representing complete coverage.
Results of these observations were as follows:
wt % Compound 18 months 12 months
0 (control) - -4~--- 5
0.065 <1 4
0.25 0 4
1.0
E. Soil burial test (cotton fibers)
A solution of compound 1 in acetone was prepared, at a concen-
tration of 0.62 weight %. The solution was applied to cotton twill
fabric; the compound was applied at 0.5% by weight based on the fabric
sample. The treated fabric was placed horizontally on a 4-inch bed of
compacted soil, covered with a l-inch layer of loosely packed soil and
placed in a humidity chamber maintained at 88F. (31.1C.~ and 90% rela-
tive humidity. After 14 days, the sample was recovered and evaluated
visually for deterioratlon. The fabric was observed to be in excellent
condition with no evidence of any deterioration or microbial growth.
F. Anti-microbial Screening Test
Samples of cotton twill coated with compound l as in test (E)
were submitted to 24 hours of exposure treatment in an enclosed single
carbon-arc fadeometer. Prior to exposure, the samples were tested for
3~3~
antibacterial and antl-fungal effect by the procedure descrlbed above in
test (B). the results of these tests are shown in the following Table
V.
TABLE V
(Zone of inhlbltion, mm/growth or stain in contact area)
(Compound 1)
Staph. K. Pink Mixed
aureuspneum. stain Fuji
unexposed >15/NG 11-15/NG 6-10/~lS 1-5/NG
24 hrs exposure >15/NG 1l -15~NG 6-lO~NS 1-5/NG
Comparative Activity Tests:
Commercial_A~ cultural and Soil_Fungicides
As U.S. Patent 3,159,532 indicates, the compounds in question
have utility as soil ~ungicides~ Several commerclal agricultural and
soil f~gicides were tested by the above-described methods to ascertain
whether any correlation could be determined between activity as a soil
fungicide and activity as a biocide for plastics or polymers. The tests
appeared to demonstrate a lack of any such correlation. In particular:
: :
Cycloheximide, 3-[2-(3,5-dimethyl-2-oxacyclohexyl)-2~ hydroxy-
ethyl]glu~aramide, tested as in (B) above, at 0.5 wt. %,
provided essentially no control of the test organisms in
the contact area, nor any zone of inhibition, both before
and after exposure.
Ihiram, bis(dimethylthio carbamoyl) dlsulfide, tested as in (B)
at levels of 0.5-2.0 wt. %, provided essentlally no con-
trol of the test organisms in the contact area with the
exceptlon of the mlxed ~ungal spore, and no 20ne of
inhibltion, with~the exception of the nixed fungal spore
; 20 at 2.0 wt. %, both before and after exposure.
Captafol,cis-N-[(1,192,2-tetrachloroethyl)thio]-4-cyclohexeene-
. 1,2-dicarboximide, tested as in (C) at 0.5 and 0.75 wt.
: :
~."x
33
%, wi th up to 300 hours exposure, controlled te.st organ-
ions as follows: Staph. aureus - 2.5-3.5 mrn inhlbition/
N; K ~neumoniae - 0.5-2 mm inhibition/N; Stv. reticulum
- 4-6 mn lnhlbition~NS; mixed fungi - 0.3 mm inhibition/N
(with large zone of inhibition of Asper~illus niger).
Captan, cis-N-[(trichloramethyl)thio]-cyclohexene-1,2- dicer
boximide, tested as in (C), at 0.5-1.05 wt. %, controlled
test organism as follows: Staph. aureus - 0.5-3.5 mm
inhibition/N; K. pneumonLae - 0-1 mm inhibition wLth no
growth in the contact area after 200 hours Or exposure,
but growth occurring after 300 hours; Stv. reticulum -
0.5-4 mm inhibition/NS; mixed fungal spore - 0-5 em
inhibition~N~ Inhibition of fungal growth dropped sharp-
ly with exposure.
Captan, however, caused yellowing of polyvinyl chloride
films after exposure. Unweathered films containing
Captan at greater than 0.5 wt. exhibited surface bloom-
lng, that is, formation of white powder on the surface,
believed to be Captan. No powder was seen on the sur-
faces of weather-exposed films; however such may have
been washed off during the exposure treatment.
Methods of Formulations:
For use as plastics or polymer biocldes~ the compounds dis-
closed herein may be incorporated in plastics or films or products made
therefrom, in an amount ranging from 0~001 to 2.0% by weight of the total
composition, preferably 0.01 to l.0, and most preferably 0.01 to 0~5% by
weight. The incorporation may be performed, as was done in the
examples, by incorporating an amounk of the biocide in a dry mix which is
then processed to produce the desired plastic or polymer or ultimate pro-
duct containing it. Alternatively, the biocide may be incorporated in a
dry blend it a hither rate, for instance, 12-13% by weight, to which a
snall amount of an extrusicn aid (for instance barium-calcium stearate)
is added, and the blend extruded to form a rcd, from whlch pellets are
cut, as described for instance in U.S. Patent 4,086,297. The pellets can
.3~
then be utilized as a means to incorporate the biocide into subsequent
plastic or polymer formulations, with the number of pellets added being
determined so as to produce an overall polymer composition including the
biocide in the desired or appropriate amount.
More commonly, the antimicrobial compound is predissolved or
dispersed in a liquid carrier solvent such as a plasticizer for a poly-
meric resin, "see for instance U.S. Patent 3,288,674", thereby providing
a vehicle for the biocide for ease of incorporation and to promote its
migration throughout the resin, particularly to its surface. Usually,
the biocide is dissolved in a first solvent and then diluted with the
desired resin-co~patible plasticizer second solvent to provide a final
liquid solution wherein the first solvent acts as a coupling solvent for
the biocide and plasticizer to maintain homogeneity. Both first and
second solvents are themselves mutually compatible with each other and
the polymeric resin system. See, for instance, U.S. Patent 3,2883674.
; For treatment of cellulosic, plastic or polymeric fibers, or
fabrics made therefrom the biocide is applied as a coating by standard
methods such as brushing, dipping or spraying, with subsequent drying, in
an amount similar to that utllized for plastics and polymers.
