Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF ~IE INVENTION
The present invention concerns a plasticized-sulfur composi-
tion and concentrates useful in its preparation. In particular, the
- fully formulated composition comprises sulfur, a sulfur plasticizer, a
filler and a triarylphosphate. The composition is particularly useful
as a coating material due to its surprising resistance to crazing under
freeze-thaw cyclic weather conditions.
Plasticized-sulfur compositions are well known in the coating
art. Various references disclose and compare the properties of these
compositions. For instance, United States Patent 3,823,019 describes
plasticized-sulfur compositions comprising sulfur, dicyclopentadiene,
glass fiber and talc. United States Patent 3,290,266 describes plas-
ticized-sulfur compositions comprising sulfur and a polymeric plasti-
cizer. United States Patent 4,026,719 describes various plasticized-
sulfur compositions. In particular, this patent discloses the use
of mica as a filler which imparts exceptional strength to the composi-
tions.
As the general state of the suLfur and plasticized-
sulfur coating art developed it became clear that these
compositions were limited by their tendency to craze or crack
when exposed to expansion or contraction stresses. Many coating
applications, such as the coating of vessels intended to hold
corrosive materials, require an essentially craze-free coating
Thus, in many cases the useful life of the coating is determined
by its craze-resistance.
SU~ARY OF THE INVENTION
It has been found that the craze-resistance of
~ conventional plasticized-sulfur compositions can be signif:l.cantly
: enhanced by adding from about 0.1% to about 30%, by weight, of a
triarylphosphate to the fully formulated composition.
Concentrates which comprise from about 40% to about 80%, by
weight of the triarylphosphate and a sulfur-plasticizer facilit-
ate formulation of the improved composition.
DETAILED DESCRIPTION OF THE INVENTION
Among other factors, the present invention is based
upon the improved properties of plasticized-sulfur coating
compositions which result from the addition of a triarylphos-
phate to the composition. Accordingly, this invention provides
a plasticized-sulfur composition comprising sulfur, a sulfur
plasticizer other than styrene or dipentene dimercaptan, a
filler, and a triarylphosphate. The composition is useful as `
a coating material in applications such as water impoundment,
floorin~, embankment consolidation, vessel lining, and the like.
In all such applications the craze-resistance of the composition
is important. A plasticized-sulfur composition containing a
triarylphosphate has been found -to provide significantly im-
proved craze-resis-tance. Thus, the advantages of the composition
of this invention over previously proposed compositions can be
readily appreciated.
The concentrations of the various ingredients which
make up the fully formulated composition may vary over a broad
; range. However, for general guidance best results have been
` observed where the fully formulated composition comprises from
about 50~ to about 98~ sulfur, from about 0.1% to about 30%
sulfur plasticizer, from about 1% to 40% filler, and from about
0~1% to about 30~ triarylphosphate (all percent concentrations
used to describe the invention, unless otherwise stated, are in
weight percent based upon total weight of sulfur, filler and
triarylphosphate in the composition)~
Sulfur is the major ingredient of the composition.
~hen fully formulated, the composition will typically comprise at
least 50% sulfur, preferably from about 60% to about 95%, and
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most preferably from about 70~ to about 90%. The sulfur may be
present in the composition as an element of the sulfur plastic-
izer, but normally the other ingredients of the composition are
added to molten elemental sulfur to form a sulfur-based formu-
lation.
The composition of this invention includes a sulfur
plasticizer. When fully formulated, the composition will
typically comprise at least 0~1% plasticizer, preferably from
about 0.5% to about 25%, and most preferably from about 1% to
about 5%. Sulfur plasticizers are well known materials. The
term is generally used to describe materials which combine with
sulfux and lower its melting point. Plasticized-sulfur therefore
requires a longer time to crystallize than molten elemental
sulfur. The rate of crystallization can be measured by melting
a fixed amount of the material on a microscopic slide at 130C,
maintaining the sample at about 78C using a surface pyrometer
to determine temperature, seeding a corner of the sample with a
crystal of the material, and recording the time required for
complete crystallization of the sample. Accordingly, as used
herein and in conventional use the term "sulfur plasticizer"
contemplates materials which, when added to molten elemental
sulfur, increase the crystallization time in reference to the
elemental sulfur itself.
Both inorganic and organic sulfur plasticizers are well
known. Inorganic plasticizers include, for example, iron,
arsenic, and phosphorus sulfides. However, organic plasticizers
which xeact with sulfur are more commonly used to plasticize
sulfur. Suitable organic sulfur plasticizers include, for
example, aliphatic polysulfides, aromatic polysulfides, dicyclo-
pentadiene, dioctylphthalate, acrylic acid, epoxidized soybeanoil, triglycerides, and tall oil fatty acids. The
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aliphatic and aromatic polysulfides are preferred sulfur plasticizers,
particularly those which do not form significantly cross-linked materials.
Thus, linear aliphatic polysulfides are one class of preferred polysul-
fide plasticizer. They may be branched such as the linear polysulfides
described by the recurring unit:
-Sx-C-c-sx-
wherein x is an integer from 2 to about 6 and Z is a hydrogen~ alkyl,
aryl, halogen, nitrile, ester or amide moiety~ Thus, the chain with
sulfur is a linear aliphatic chain, but may contain aromatic or hetero
side groups. For instance, styrene can be used to form a phenyl substi-
tuted linear aliphatic polysulfide. The aliphatic polysulfides may
also be unbranched such as those described by the recurring unit
-SXcll2ctl2oc~l2oc~l2c~l2sx-
wherein x has an average value of about 12. The ether function of the
polysulfide is relatively inert. Other suitable aliphatic polysulfides
havln~ recurring ~mits such as
-Sx~C1~123ySx~,
-SX~CH2CH2-S-CH2CH23ySx~, or
~, -SX~cH2cH2-o-cH2cH2~ysx
wherein x is an integer from 2 to about 5 and y is an integer
from 2 to about 10. Aromatic polysulfides formed by reacting at
, least two mols of sulfur with one mol of an aromatic carbocyclic
! or heterocyclic compound substituted by at least one functional
_ 5 _
~,~
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group of the class -OH or ~NHR in which R is hydrogen or lower
alkyl are another class of preferred polysulfide plasticizer.
These as well as other suitable sulfur plasticizers are disclosed
in United States Patent 4,026,219. For example, the reaction
product of phenol and sulfur is a preferred plasticizer and is
generally called a phenol-sulfur adduct. In particular, these
disclosures describe suitable mixtures of sulfur plasticizers
such as mixtures of aliphatic polysulfides with dicyclopenta-
diene.
The third ingredient of the composition of this inven-
tion is a filler. Organic and inorganic, particulate and fibrous
fillers are conventionally included in plasticized-sulfur coating
compositions. In general, when fully formulated, the composition
will comprise at least 1% filler, preerably from about 5% to
about 30%, and most preferably from about 10% to about 20%.
Suitable fillers include, for example, glass fibers, asbestos,
talc, clay, mica, and the like. Mica is particularly suited.
United States Patent 4,026,719 thoroughly describes mica fillers
which are preferred for use in the composition of this invention.
As indicated in the previous description of the composi-
tion of this invention, a triarylphosphate is the most critical
ingredient of the composition. In general, the fully formulated
composition will comprise at least 0.1% triarylphosphate, pre-
ferably from about 0.5% to about 25%, and most preferably from
about 1% to about 5~. The triarylphosphates have some plasticiz-
ing properties, but for purposes of this description, they are
distinguished from the sulfur plasticizer which is an ingredient
of the composition. Thus, the total concentration o~E triaryl-
phosphate in the fully formulated composition may exceed 30%,
if the amount of sulfur plasticizer is less than 30%.
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Suitable triarylphosphates include, for example, phosphates having from
6 to about 12 carbon atoms in cach aryl substituent. The aryl substitu-
ents can be similar or dissimilar and may have a condensed or fused ring
system. Accordingly, preferred triarylphosphates have the structure
o
Ar-O-P-O-Ar
o
Ar
wherein Ar is an aryl group containing from 6 to about 12 carbon atoms,
optionally substituted with from 1 ~o 5 halogen atoms, preferably chlor-
ine. The three Ar groups may be the same or different. Specific suit-
able aryl group include, for e~cample, phenyl, benzyl, naphthyl, tolyl,
xylyl, mixed ethyl phenyls, 4-t-butylphenyl, pentachlorophenyl, 3-
bromophenyl, p-phenylphenyl, 2-methyl-1-naphthyl, and the like. Aryls
which are substituted by alkyl groups containing more than one carbon
atom, i.e., al~ylaryls "~hile s~litable are less proferred since they
may liberate ~12S or CS2 cluring formulation. Triphellylphosphate and
tribenzylphosphate are the preferred triarylphosphates.
Aryl phosphates are made by the reaction of the phenol with
phosphorus o~ychloride:
3ArOH I POC13~ ~ArO)3P0 ~ 3HCl.
In addition to the four essential ingredients described
above, the composition of this invention may optionally comprise
various other adjuvants such as pigments, stabilizers, aggregates
including sand, gravel, or rock, and the like. Particularly
where aggregate is included, t1~e adjuvants may be present in
amounts up to as moch as 90% by weight of the total composition.
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The composition of this invention can be prepared in
molten form by mi~ing the ingredients at a temperature above the
melting point of the composition. For most embodiments, a
- temperature between about 110 C and 180 C, preferably between
about 125 C and 150 C, is sufficient. ~lowever, for most
applications, the composition is prepared from a concentrate
comprising the sulfur plasticizer and the triarylphosphate. In
addition, the concentrate may contain the filler or a fraction of
the filler and/or a fraction of the sulfur present in the fully
formulated composition. Thus, this invention contemplates a con-
centrate which when diluted by the addition of sulfur and filler
provi(les a fully formulated plasticized-sulfur coating composition.
The relative concentration of the plasticizer and triarylphosphate
in the concentrate will depend upon the desired relative concen-
tration in the fully formulated composition. A concentrate
comprisin~ the sulfur plasticizer and tho triarylphosphate in a
weight ratio of plasticizer to phosphate of from about 3:1 to
about 1:3 is satisfactory for most applications.
The most practical method of preparing the composition
of this invention from a concentrate is to add the concentrate
and additional filler as well as any other optional adjuvant to
molten sulfur at a temperature above the melting point of the
composition. The order of addition is not critical, although for
thorough mi~ing aggregate, if used, should be added a fraction at
a time or continuously during the entire formulation process.
The fully formulated composition is usually applied in
molten form by, for e~ample~ spraying or painting a coat onto the
surface to be covered. For most surfaces a llS" to 1/4" uniform
coat will provide complete coverage.
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E~IPLES
The following examples illustrate a variety of
embodiments of the composition and concentrate of this invention.
The examples also suggest numerous modifications within the scope
of the claims which follow, and therefore are not presented to
limit the scope of the invention.
Examples 1-10
The plasticized-sulfur coatings summari~ed in Table I
which comprise sulfur, a sulfur plastici7er, a filler, and a
triarylphosphate are prepared in molten form by heating and
mixing the components at a temperature of about 130C.
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TABLE I
Ex.
No. Sulfur, % Plasticizer, % Filler, % Triarylphosphate,%
1 50 DCP 5 Talc 40 Triphenyl-
phosphate 5
2 60 LP-3 * 1 Mica5 30 Tribenzyl-
phosphate 9
3 80 PSA3 2 Abestos 16 Tri(ethylphenyl)-
phosphate 2
4 90 PSA 2 Clay 2 Trinaphthyl-
LP-3 1 phosphate 5
DCP 10 Glass7 25 Triphenyl-
phospha-te 5
6 60 PSA 2 Mica 20 Tri(dimethylphen-
yl)-phosphate 18
7 70 LP-3* 5 CaCO 20 Tritolyl-
3 phosphate 5
8 80 DCP 5 Mica 15 Tritbisphenyl)-
phosphate 10
9 90 DCP 2 Talc 1 Tri(butylphenyl)-
LP-3* 1 Asbestos 1 phosphate 5
LP-3* 1 Mica 1 Triphenyl-
phosphate 3
Dicyclopentadiene.
3I.inear aliphatic polysulfide sold by Thiokol Co.
Phenol-sulfur adduct.
4Mistron Vapor.*
C-3000* sold by English Mica Co. having a
6 particle size of 5-10 microns by 0.5 micron.
7Kaopague-30*.
0.25" milled glass fiber.
Example 11
A plasticized-sulfur coating composition was prepared
by heating and mixing 79% sulfur, ~% phenol-sulfur adduct, 18%
mica, and 1% triphenylphosphate at a temperature of abc,ut 130 C.
The resulting composition was applied to a 10-foot by 6-foot T-
shaped mortarless cinderbrick wall. The composition was thixo-
tropic and did not sag or drip during application.
The composition was evaluated for flexural strength,
tensile strength, and compressive strength. These properties
are summarized in Table II.
* Trademarks
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TABLE II
Flexural Tensile Compressive
Strength Strength Strength
psi psi psi
1800 1050 3300
The composition was also evaluated for craze-resistance
under cycling temperature conditions. In these tests the composition con-
tained 7g% sulfur, 2% phenol-sulfur adduct, and 18% mica. The results are
given in Table III.
TABLE III
Ex. Anti-Crazing Tes~ I, Cycles~ ) Test II, Cycles
No. Additive, % Failure No Failure Failure No Failure
12 LP-~2)) 1 60 6
13 TPP 1 91 28
14 TCP(3)4) 1 38
lS BPDPP 1 38
(1) LP-3 is a linear aliphatic polysulfide.
(2) Triphenylphosphate.
~3) Tricresylphosphate.
(4) t-Butylphenyl diphenyl phosphate.
(5) 1 cycle equals 8 houOrs at 70C and
16 hours at about 5 C.
~6) 1 cycle equalO S hours at 70C and
16 hours at 0 C.
E~ample 12, a good non-crazing composition without a triaryl
phosphate, resisted crazing for 60 cycles in Test I and for 6 cycles in
Test II, ~hereas a comparative composition containing triphenyl phosphate
did not craze until 90 and 28 cycles respectively.
In Test I, compositions containing different aliphatic phosphates
failed after 7 to 9 cycles.
