Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
The present invention relates to plasticized sulfur prepared by
specified heat~ng and cooling. The plasticized sulfur is a good adhesive
and can be used as a bonding agent in making pipe out of layers of paper.
Plasticized sulfur ~as been disclosed in various references,
for example 6y J. I~ Jin in "Chemistry of Plasticized Sulfur", Petroleum
Division, A.C.S. Symposium, Vol. 19, No. 2, March 1974, pp. 234-241, and
by C. Kinney Hancock in "Plasticized Sulfur Compositions for Traffic
Marking", Industrial and Engineering Chemistry, Vol. 46, ~o. 11, November
1954, pp. 2431-2435. Exemplary patents disclosing plasticized sulfur (and
heating temperatures at which the plasticized sulfur is formed) include
United States Patent 2,169,814, "Bonding and Coating Product" ~heating
temperatures of 150-160C); United States Patent 3,306,000, "Construction
Method" (heating temperatures of 135-1751C); United States Patent
3,316,115, "Marking Composition" ~heating temperature of 160C); United
States Patent 3,371,072, "Sulphur Resins" (heating temperatures of 100-
200C, preferably 110-160C); United States Patent 3,384,609, "Plasticized
Sulphur" Cheating temperatures of 120-250C, preferably 140-160C); United
States Patent 3,434,852, "Plasticized Sulfur Compositions" ~heating
temperatures of 50-250C, preferably 100-200C, and exemplary temperatures
of 130-170C); United States Patent 3,447,941, "Sprayable Sulfur Road
Marking Compositions" ~heating temperature of 150C); United States Patent
3,453,125, "Plasticized Sulfur Compositions" (heating temperatures of
-20-250C and exemplary temperatures of 138-170C); United States Patent
3,459,717, "Sulfur-Based Plastic Composition" ~heating temperatures of
115-200C, preferably 140-170C); United States Patent 3,465,064,
"Adhesive Plastlcised Sulphur Containing an Olefine Polymer" ~heating
temperatures of 100-200C, preferably 140-150C); United States Patent
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10'7~:i7Z~i
3,560,451, "Plastic and Nonflammable Sulfur Composition" (heating tempera-
tures of 120 - 180C, preferably 140 - 160C); United States Patent
3,640,965, "Thermoplastic Sulfur Containing Polymers"; United S~ates Patent
3,674,525, "Plasticized Sulfur Compositions" (heating temperatures of
50 - 250& and exemplary temperature of about 155C); United States Patent
3,676,166, "Plasticized Sulfur Compositions" (heating temperatures o~ 75 -
400F, preferably 250 - 350F, and exemplary temperature of 300F); United
States Patent 3,734,753, "Plasticized Sulfur Compositions" (heating tempera-
tures of 118 - 250C, preferably 150C); and United States Patent 3,787,276,
"Corrugated Cardboard Containing Sulphur Foam" (heating temperature of
110C); also Serial No. 286,627, now United States Patent 3,283,019, "Mine
Wall Coating" (heating temperatures of 240 - 320F, preferably 275 - 320 F),
which application has been offered for license by the United States Bureau
of Mines, discloses plasticized sulfur compositions.
As can be seen from the examples in the above patents,
temperatures which are su~gested by the patents for heating or carrying out
a reaction to obtain the plasticized sulfur compositions are generally
about 150C (302F). United States Patent 3,734,753 thus dlscloses at
column 2, line 50, with respect to preparation of plasticized sulfur compo-
sitions: "It is preferable to maintain the temperature of the reaction
mixture at about 150C since pure sulfur becomes viscous at 160& and
higher temperatures raise the cost of processing."
"Elemental Sulfur," edited by B. Meyer, Interscience Publ.
(1965) discloses in Chapter 5 the sharp increase in sulfur viscosity at
about 159C. Chapter 8 of "Elemental Sulfur" discloses as follows:
"Both the arsenic-modified and phosphorus-modified
systems are dark red in color, have ob~ectionable odors, and tend to
recrystallize when
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exposed to light and air. Arsenic-sulfur systems
are more stable and such materials have been fabri-
cated into a variety of products including lenses,
prisms, tubes, and fibers.
"Polymeric sulfides and polysulfides are more
promising modifiers for elemental sulfur, tending
to stabilize the material in a plasticized form.
These materials, on heating with sulfur to tempera-
tures above its polymerization point (159C), form
viscous liquids which on cooling show distinct
polymeric properties. These compositions recrys-
tallize elemental sulfur only after comparatively
long periods of time, depending upon the concen-
tration of polysulfide polymers used ... Composi-
tions having as little as 10-15% of the polymer
[ethylene tetrasulfide], after heating to 160-175C,
remain in a polymeric form several days before
completely recrystalling. Larger quantities
of the ethylene tetrapolysulfide give pliable ma-
terials which remàin largely unchanged in properties
for several weeks, following which hardening occurs
on the recrystallization of sulfur.
"Mixtures of ethylene polysulfides with sulfur
have been studied extensively by Tobolsky and co-
workers [J. of Polymer Sci. A2, 1987 (1964)]. Both
linear and crosslinked systems have been produced.
Each produces~;extensive supercooling Of sulfur.
Systems containing as much as 40% supercooied liquid
sulfur have remained free of crystallization for
3Q over three years."
In one of its embodiments, the present invention is
also concerned with a method for preparing laminated conduit or
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pipe. Exemplary prior art patents in this area include United States
Patents 1,943,501, "Manufacture of Paper Tubes", for example
shotgun shells; 3,055,278, "Reinforced Plastic Pipe";
3,323,961, "Reinforced Resinous Tubular Laminates" for use in
electrical insulating, etc.; and 3,767,500, "Method of
Laminating Long Strips of Various Materials".
SUMMARY _F THE INVENTION
In accordance with the present invention a composi-
tion is provided comprising plasticized sulfur wherein the
composition is prepared by steps including heating the plasti-
cized sulfur to a temperature between 160C and 220C and then
cooling the hot plasticized sulfur in liquid form to a tempera-
ture below 160C to thereby obtain a liquid, tacky, plasticized
sulfur. Preferably, the hot plasticized sulfur is cooled to a
temperature below 155C, for example a temperature of 150C or
lower. The tacky plasticized sulfur tends to stay tacky or
adhesive-like for a longer length of time than does plasticized
sulfur not subjected to the heating treatment in accordance
with the present invention. Also, I have found that the
plasticized sulfur can generally be cooled to a temperature
below its normal melting point to thereby obtain a super-cooled
plasticized sulfur which exhibits good adhesive properties.
Further, the plasticized sulfur, especially when plasticized
with dicyclopentadiene, exhibits lower viscosity at high tem- -
peratures of about 160-220C, preferably 170-210C, than does
pure sulfur at these high temperatures. This makes the
plasticized sulfur relatively easy to work with in obtaining
the tacky, cooled plasticized sulfur composition. The -
relatively reduced viscosity ~compared to pure sulfur) is not ~ -
as reduced at the high temperature when fillers such as talc
are included in the composition.
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The plasticized sulfur comprises sulfur reacted with
an organic compound effective to plasticize the sulfur as is de-
scribed in more detail hereinbelow. Preferably the plasticized
sulfur is brought to a temperature between 170 and 210C before
the cooling step, and still more preferably between 175 and
210C before the cooling step. Tackiness is enhanced by the in-
clusion of materials such as talc, mica and other finely divided
mineral fillers. Tackiness for the composition having only an
organic plasticizer usually does not develop unless the compo-
sition is impregnated or coated on a substrate such as paper or
a paper-like material.
According to a preferred feature of the present in-
vention, an adhesive composition is provided wherein the adhesive
is prepared in accordance with the steps described above. It has
been found especially advantageous to use the compositions of the
present invention as adhesives or bonding agents after they have
been cooled somewhat, and preferably while in the super-cooled
liquid state, as opposed to after the compositions arrive at
steady-state equilibrium and become solidified masses. Using the
compositions after cooling, and preferably while super-cooled
liquid, facilitates relatively easy handling at or about room
temperatures of 40 - 50C, more usually about 12 - 38C.
The adhesive composition also has the advantageous
properties of being usually water-tight and chemical-resistant,
particularly acid-resistant.
The composition obtained via the heating procedure of
the present invention is particularly advantageous in that upon
cooling it retains liquid characteristics longer so that upon
thermal contraction due to cooling relatively few stresses are
created, compared to what would be the case with normal solidi-
fication at the normal melting point and then cooling of the
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solid. In such normal cooling, stre~ses axe apt to nake cracks or warp the
material. m erefore, one adYantageous appllcatlon of the present compo~ltLon
is in areas where minimal cracking and the like is important. The composition
i5 advantageously used to make castings andfor molas wherein it is desired to
avoid or reduce cracking and formation of stresses upon coollng.
me composition of the present invention is also advantageously
used in forming paper proaucts, in packaging, in forming containers such as
barrels or boxes, and in forming construction panels and construction members.
The composition is useful as a reinforcement medium with paper and wood pro-
ducts as well as an adhesive and thus can advantageously be used in laminatinglayers o~ paper or paper-like material into a container wherein the adhesive
composition is used to hold the paper or paper-like material together. The
composition can be used as an adhesive simply to hold the layers together,
but also can be used at the seams or edges of a container to hold the seams
or various sides of the container together.
According to another preferred feature of the present invention, a
laminated conduit or pipe is provided. The conduit or pipe is prepared by
steps comprising laminating layers of paper or paper-like material into a
conduit or shape using plasticized sulfur, preferably the plasticized sulfur ~-
adhesive composition described above, to hold the layers together.
~ hus this invention provides in a paper or paper-like product
comprising layers laminated together by a plasticized sulfur adhesive, the
improvement which comprises preparing the plasticized sulfur adhesive by
heating to a temperature between 160C and 220C to obtain a molten, low
viscosity adhesive.
Preferably, the hot plasticized sulfur is cooled in liquid form to
a temperature below 150& to obtain a liquid adhesive.
Suitable types of paper or paper-like material which may be used for
forming the conduit or pipe and also for forming other articles such as con-
tainers using the compositions of the present invention include Kraft paper,newspaper, tissue, felt, cardboard, bagasse, cotton, cloth as natural or syn-
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thetic, poly~rQpy~lene felts, and fibe~ in ~yen, rando~ or
Spun form.
Tfie tacky compositions of the present invention can
fie advantageously used to form structures due to the adhesive
cfiaracter of the composition. Structural ~embers can be bonded
together using the composition and also structural members such
as beams or poles can ~e built up using the composition as a
rigidifying and 6Onding agent. Advantageously beams or poles
and the like can be made from fibers, synthetic or natural, or
wood products with the plasticized sulfur composition serving
to hold the components of the member together and rigidifying
the structural member.
Among other factors, the present invention is based
on my finding that plasticized sulfur prepared as described
herein has especially advantageous tackiness after cooling and
also tends to retain tackiness even below its normal solidifi-
cation temperature, and hence has resultant advantageous prop-
erties as an adhesive or bonding agent. Heating to a lower
temperature -- for example 150C (302F), typically employed in
the prior art of plasticized sulfur -- does not achieve the
highly workable plasticized sulfur composition as in the
present invention, especially the tacky, liquid composition
obtained directly after the cooling in accordance with the
present invention.
Although the composition of the present invention can
be used after both the heating to a temperature above 160C,
and the cooling to a temperature below 160C, the hot plasti-
cized sulfur can also be used while it is at a high molten tem-
perature, which may or may not be above the 160C temperature.
The h~t, molten, plasticized sulfur in any case must be heated
to a temperature above 160C, and preferably above 170C, in
accordance ~lth the present invent~on so that t~e compos~tion
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of the present inyention can subsequently be ohtained either in
s~tu or as a transitional composition ater application of the
hot plastici~zed sulfur to paper or other su6strate. Thus,
paper or other substrate can be impregnated ~ith ~ot
plasticized sulfur above the melting point and t~en cooled --
for example super-cooled to ~elow the melting point to obtain a
surface still tacky or adhesive, for instance like Scotch tape.
The thus-obtained surfaces are then preferably bonded together
or to another object before solidification of the cooled
plasticized sulfur occurs. Time limits while the material
remains tacky or nonsolidified will, of course, exist and will
be a function of the time and amount of heating as well as of
the amount and type of plasticizer used.
The term "liquid" plasticized sulfur is used herein
to embrace nonsolidifed and nonrigidifed plasticized sulfur.
For example, plasticized sulfur which is still tacky or which
has not solidified sufficiently to rigidify paper impregnated
with the plasticized sulfur is considered to be "liquid"
plasticized sulfur.
Plasticized sulfur compositions contemplated by the
present invention preferably contain principally sulfur. Pref-
erably the plasticized sulfur contains more than 50 weight per-
cent sulfur and more preferably about 70-90 weight percent
sulfur or more.
- "Plasticized sulfur" as the term is used herein
usually has a slightly lower melting point than elemental
sulfur. Furthermore, plasticized sulfur requires a longer time
to cry~tallize; i.e., the rate of crystallization of
plasticized sulfur is slower than that of elemental sulfur.
One useul way to measure the rate of crystallization is as
follows-: t~e test material (0.040 g~ is melted on a microscope
sl~de at 13QC and i5 t~en coveTed ~ith a ~quare m~croscope
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slide cover sllp. The slide is transferred to a hot plate and is kept at
a temperature of 78 + 2C, as measured on the glass sllde using a surface
pyrometer. One corner of the melt is seeded with a crystal of test
material. The time required for complete crystallization ls measured.
Plasticized sulfur, then, is sulfur containing an additive which increases
the crystallization time within experimental error, i.e., the average
crystallization time of the plasticized sulfur is greater than the average
crystallization time of the elemental sulfur feedstock. For the present
application, plasticizers are those substances which, when added to molten
elemental sulfur, cause an increase in crystallization time in reference to
the elemental sulfur itself. In one set of experiments, elemental sulfur
required o.44 minute to crystallize under the above conditions, whereas
sulfur containing 3.8% of a phenol-sulfur adduct (as described in United
States Patent 3,892,686, filed March 26, 1973) required 2.9 minutes. Sulfur
containing 6.6% and 9.9% of the same phenol-sulfur adduct required 5.7
and 22 minutes, respectively.
InOrganic plasticizers include iron, arsenic and phosphorus
sulfides, but the particularly preferred plasticizers are organic compounds
which can react with sulfur to give sulfur-containing materials, such as
styrene, alpha-methylstyrene, dicyclopentadiene, vinyl cyclohexene, the -
aronatic compound-sulfur adducts of United States Patent No. 3,892,686, as
well as the aromatic compounds used to produce these adducts, aromatic or
aliphatic liquid polysulfides (e.g., those sold under the trade names of
Thiokol LP-3* or LP-32*), and the viscosity-control agents described in
United States Patents 3,674,525, 3,453,125 and 3,676,166. The preferred
aromatic plasticizing ccmpounds are styrene and the phenol-sulfur adduct of
United States Patent
*Trade Marks
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3,892,686. The preferred aliphatic compound is dicyclopentadiene.
~ ne preferred plasticized sulfur substance contains di-
cyclopentadiene, sulfur, glass fiber and talc. It has also been found that
asbestos can advantageously be used instead of glass fiber in the above
plasticized sulfur substance.
The elemental sulfur may be either crystalline or amorphous,
and may contain small amounts of impurities such as those normally found
in commercial grades of sulfur. Optimum proportions of sulfur, as well as
of the other components of the composition, may vary considerably. However,
proportions of sulfur of about 73% to 97%, by weight, are generally
satisfactory.
Dicyclopentadiene is readily available commercially,
generally at a purity of about 96% or greater. Preferably it is used in
the above preferred plasticized sulfur composition in an amount of about
1 to 7% by weight.
The glass fiber of the preferred plasticized sulfur compo-
sition is preferably employed in the form of milled fibers, with the fibers
generally ranging from about V 32" to 1/4" in length, preferably with an
average length of about 1/16". These fibers, which generally consist of
high-silica glass, are readily available commercially, often coated with a
starch binder. The type of glass is, however, not critical, as long as it
provides the resulting composition with adequate shear strength, preferably
a shear strength of about 400 to 800 psi. me glass fiber preferably con-
stitutes about 1 to 5% by weight of the composition of the invention.
The talc used in the preferred dicyclopentadiene-su~fur-
glass fiber-talc composition preferably is a foliated type, or a compact
variety such as steatite. Impure varieties such as soapstone can also be
used. This ingredient is
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p~e~erably ~sed in an a~unt o~ ahQut 1 to 15~ by weight o the
composition, and serYeS the dual function o pr~id~ng
th~xotrop~ to the m~xture and of dispersing tfie glass iber
throughout the composition, there~y~preventing agglomeration of
the fibers.
EXAMPLES
ample 1
A plasticized sulfur was prepared b~ mixing about 2
weight percent organîc plasticizer, namely dicyclopentadiene,
with molten sulfur.
Eight-mil-thick Kraft paper coupons were treated with
the molten plasticized sulfur at various temperatures~ The
paper coupons were dipped into the molten plasticized sulfur
and then hung up to dry by exposure to room-temperature air.
The time was recorded when the first dry spot appeared, when
the coupons were 50% dry, and when they were 95% dry. The term
`'dry" is used here to denote becoming solidified and nontacky
rather than in the normal sense of drying by evaporation of a
solvent.
The impregnated coupons contained about 85 weight
percent plasticized sulfur. In practicing the present
invention, the paper or paper-like material can be impregnated
or coated with about 5 to 90 weight percent plasticized sulfur
Cbased on the paper and plasticized sulfur), but preferably
about 10 to 50 weight percent is used. Thus the 85 weight
percent is somewhat higher than normal.
When the plasticized sulfur had been heated at 150C
fQr 1 ~r 2 hours, it solidiied and became nontacky very
~apidly ~hen impregnated onto the paper. See Tahle I below.
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TABLE ~
pa~er ImpregnatIon at Constant Temperature
Plastici~ed Sulfur
Heat~ng Time Dr~n~ Time J M~nu~es
at 15a C, Hours Start50% Dr~ 95% Dry
1 Past Fast 0.1
3 2 6 15
4 3 8 17
8 3 10 17 :: :
~hen the plastîcized sulfur was heated to higher tem-
peratures than 150C, it took longer to dry or solidify. See
Table II.
TABLE II ~ ,
~' ~ ', .
Paper Impregnation at Variable Temperatures :
Elapsed
Time for ~
Plasticized Sulfur Heating, Drying Time, minutes ~ :
eating Steps hours Start 50% Dry 95% Dry
1 hour at 160C 1 3 5 9
Raise T to 170C 1-1/2 5 13 22
Take out of oven
~ cool to 135C 1-5/8 3 8 22
Raise T to 150 C 1-3/4 4 16 30
Raise T to 195C 2-1/4 9 23 47
' ~ .
Thus, comparing the data of Table I to Table II, it
is seen that if plasticized sulfur is heated at 160-170C or ~.
higher, then a plasticized sulfur which gives delayed solidi- ~ :
fication is formed faster (compared to when lower heating tem-
peratures are used); and it also gives more delayed solidi- -
fication or more prolonged retention of adhesiveness or tacki-
ness.
Example ?
A plasticized sulfur composition containing sulfur,
dicyclopentadiene, talc and glass fibers was prepared as
follo~s:
A stainless-steel beaker equipped with a stirrer is
charged wit~ qQ parts of sulfur which is then heated until
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molten. While maintainln~ the temperature of the sti~red,
molten sulfur at 138C, 1.8 parts of dicyclopentadiene ~s
added. After 10 minutes of reaction t~me, 6.4 parts of talc
CMistron Vapor talc~ ~s added. Then, after the talc i5 well
m~xed in, 1.8 parts of 0.25" milled glass fiber ~O~ens-Corning
#630 glas-s fiber~ is added. Stirring at 138C is then
continued for an additional 1/2 hour. Upon cooling to room
temperature, this material forms a hard, opaque mass which can
be broken into smaller pieces for ease of handling.
The plasticized sulfur composition obtained as a60ve-
described was used in the construction of a container, in par-
ticular the construction of a box which had a suhstantial
degree of water-tightness retention ability. Thus, a~out 2
grams of plasticized sulfur was placed on a hot plate and
heated to a temperature of about 185 C. The molten material
was spread out with a spatula to a thickness of about 1/64".
Then a 4"x4" piece of Kraft bag paper was placed on the molten,
highly viscous plasticized sulfur and was gently pressed down
with the spatula over its surface. Then, while still in place
on the hot plate, a second 2 grams of plasticized sulfur was
placed on top of this Kraft paper and was allowed to melt.
This material was likewise spread over the entire upper surface
of the paper. Then a second 4"x4" piece of Kraft bag paper was
placed over the first and pressed down with a spatula.
Finally, a third 2-gram portion of plasticized sulfur was
placed on the top of the 2 plies of paper and allowed to melt
and spread.
~hile still hot (about 185C), the plasticized
sulfur-impregnated 2-ply paper laminate was removed from the
hot plate and cooled to room temperature in about 10 seconds.
The laminate was plastic and ~as sticky on fioth surfaces. It
~a~ f~med into a ~x fiy olding the sides up and lapping the
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corne~5. Th~ seams ~ere closed ~y squeezing the edges
tagether~ Tfiis box held ~ater ~Ithout lea~age for more than 24
h~urs~.
Example 3
The plasticized sulfur of Example 2 was utilized to
orm a laminate from 12 plies of newspaper, about 3"x3", by the
same technique as described in Example 2. After the 12-ply
laminate was removed from the hot plate and rapidly cooled to
20C, it was rolled into a tube which was sealed by pressing
t~e edges together with about a l/2" overlap. After about l/2
hour, the tube lost its plasticity and set to a rigid tubular
structure. The tube was unaffected by immersion in water.
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