Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF T~E INV~NTION
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The present invention relates to a synthetic turf
or carpet-like manufacture comprising a plasticized sulfur
i matrix.
Prior patents disclosing synthetic turfs include
U.S. Patents 3,422,615; 3,332,828; 3,157,557; 2,515,~47;
2,061,750; and 1,939,846.
U.S. Patent 3,422,615 discloses a synthetic turf-
like material which i5 referred to as a pile fabric. Fibers
which are indicated as being suitable for making the yarns
used to make the pile fabric of USP 3,422,615 are said to
include olefins, particularly polypropylene, nylon, vinyl,
vinylidene chloride, polyvinyl chloride, polyethylene,
polyester, polyacrylonitrile, acetate, triacetate, rayon
(cellulosics), and glass.
U.S. Patent 3,332,828 relates to artificial turf
preferably produced by weaving synthetic fibers on a Wilton
cut-pile loom to form a structure consisting of a woven
backing having a cut-pile face extending from one surface
thereof and then applying a suitable latex formation on the
other surface of the backing to render the complete ~tructure
dimensionally stable.
U.S. Patent 3,157,557 discloses an integrally molded
plastic sod simulating natural grass and comprising a flat
flexible base of a thick plastic material having a multiplicity
of closely-spaced blade-like plastic stems molded integral with
the base.
U.S. Patent 2,515,847 discloses a surfacing structure
suitable for use as a putting green for golf. The surfacing
structure includes a top layer of rug material having a nap.
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The rug ~aterial is supported on center layers of sponge
rubber-like material. The supported rug material is placed
upon the earth.
United States Patent 2,061,750 relates to grass mats
prepared by stitching grass simulated material to a base.
United States Patent 1,939,846 discloses distributing
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fibrous material evenly over the top of a sheet of rubber composi-
tion and then vulcanizing the fibers to the sheet in a heat press.
Plasticized sulfur has been disclosed in various
references, for example by J. I. Jin in "Chemistry of Plastic-
ized 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, No. 11, November 1954,
pp. 2431-2435. Exemplary patents disclosing plasticized sulfur
include USP 3,316,115 "Marking Compositions"; USP 3,434,852
"Plasticized Sulfur Compositions"; USP 3,447,941, "Sprayable
; Sulfur Road Marking Compositions"; USP 3,459,717 "Sulfur Based
Plastic Composition"; USP 3,560,451 "Plastic and Nonflammable
Sulfur Composition"; USP 3,453,125 "Plasticized Sulfur Compositions";
; USP 3,674,525 "Plasticized Sulfur Compositions"; and USP 3,676,166
"Plasticized Sulfur Compositions". Also United States Patent
3,823,019, which has been offered for license by the United States
Bureau of Mines, discloses plasticized sulfur compositions.
According to the present invention a manufacture is
provided comprising a plurality of fibers partially embedded in a
solidified plasticized sulfur matrix with one end of the fibers
extending outward from the matrix to form a turf or carpet-like
i~ surface.
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According to a preferred embodiment of the present
invention the sulfur is plasticized with dicyclopentadiene,
aliphatic polysulfide, aromatic polysulfide, or mixtures
thereof.
The term "fiber" is used herein to include mono-
filament strands as well as polyfilament strands (yarns and
threads and yarns made by twisting a fibrillated thermoplastic
tape). Preferably yarn is used to form the product of the
present invention. The yarn can be produced by twisting
filaments together by methods known in the carpet-producing
art. In this regard, see, for example, U.S. Patent 3,422,615.
Materials which can be used as the monofilament strands or as
the polyfilament strands, that is~ yarns, include synthetic
plastic materials as well as animal-derived materials'such as
wool. Preferably, synthetic materials are used, i.e., synthetic
plastic materials capable of being formed into filaments and
yarns, for example by extruding into a pellicle and then cut
or shredded into filaments which can in turn be converted to
yarns. Polypropylene is a particularly preferred synthetic
"20 plastic material for forming fibers for use herein, and a
particularly preferred polypropylene yarn is made by twisting
fibrillated polypropylene tapes. Other materials which can be
used include other polyolefins, polyethylene terephthalate,
polyacrylonitrile, viscose rayon, cellulose acetate, nylon,
polyvinyl chloride, and fibrous glass.
In addition to U.S. Patent 3,422,615, U.S. Patents
3,177,557, 3,242,035 and 3,332,828 disclose materials which
can be used to produce monofilament strands as well as poly-
filament strands (yarns) for making artificial turf.
Among other factors the present invention is based
on my finding of the surprisingly advantageous adherence of
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solidified plasticized sulfur to fibers, especially fibcrs
such as polypropylene, and especially polypropylene in the
form of pieces of yarn. ~lso the combination product of the
present invention has been found to poss~ss particularly
attractive durability and serviceability characteristics
so that it can advantageously be used in surfaces subjected
to abusive foot traffic.
Plasticized sulfur as the term is used herein
usually has a lower melting point and a higher viscosity
than elemental sulfur. Furthermore, plasticized sulfur
requires a longer time to crys~allize; i.e., the rate of
crystallization of plasticized sulfur is slower than that
- of elemental sulfur. One useful way to measure the rate of
crystallization is as follows: the test material (0.040 g)
is melted on a microscope slide at 130C. and is then covered
with a square microscope slide cover slip. The slide is
transferred to a hot-plate and is kept at a temperature of
78+2C., as measured on the glass slide using a surface
pyrometer. One corner of the melt is seeded with a crystal
of test material. The time required ~or complete crystal-
lization is measured. Plasticized sulfur, then, ic sulfur
containing an additive which increases the crystallization
time within experimental error, i.e., the average crystalli-
zation 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. ~n one set of experiments, elemental sulfur required
0.44 minute to crystallize under the above conditions, whereas
sulfur containing 3.8% of a phenol-sulfur adduct (as described
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in United States Patent 3,892,686) 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, alphamethylstyrene, dicyclopentadiene, vinyl cyclohexene, the
aromatic compound-sulfur adducts of United States Patent 3,892,686 as well
as the aromatic compounds used to produce these adducts, aromatic or ali-
phatic liquid polysulfides (e.g., those sold under the trade mark of ThiokolLP-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 plastic-
izing compounds are styrene and the phenol-sulfur adduct of the aforesaid
United States Patent 3,892,686. The preferred aliphatic compound is
dicyclopentadiene.
One preferred plasticized sulfur substance contains dicyclo-
pentadiene, sulfur, glass fiber and talc.
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 satisfact-
ory~
; Dicyclopentadiene is readily available commercially, gener-
ally 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-
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sition is preferably employed in the form of milled fibers, with the fibers
generally ranging from about 1/32 to 1/4" in
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length, preferably with an average length of about l/16".
These fibers, which generally consist of high-silica glass,
are readily available co~nercially, 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.
The glass fiber preferably constitutes about l to 5% by weight
of the composition of the invention.
The talc used in the preferred dicyclopentadiene-
lQ sulfur-glass fiber-talc composition prefera~ly is a foliated
type, or a compact variety such as steatite. Impure varieties
such as soapstone can also be used. This ingredient is
preferably used in an amount of about l to 15~ by weight of
the composition, and serves the dual function of providing
thixotropy to the mixture and of dispersing the glass fiber
throughout the composition, thereby preventing agglomeration
of the fibers.
The preferred composition is used as a fluid mixture
of the ingredients, with the sulfur and dicyclopentadiene in
molten form and the glass fiber and talc distributed throughout
the molten material. Thus the composition is prepared by
homogeneous mixing of the ingredients at elevated temperature
sufficient to maintain the sulfur and dicyclopentadiene in a
molten state. A temperature of about 240 to 320~. is
satisfactory, with about 275 to 320F. being preferred. Any
conventional vessel or reactor capable of providing the required
temperature and mixing means may be used for preparation of the
composition.
DRAWING
The drawing is a schematic illustration of an
embodiment of the present invention. As shown in the drawing
the plasticized sulfur rests on the soil or floor, and yarns or
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fibers are embedded into the plasticized sulfur. The thickness of the
plasticized sulfur can vary but typically is between abou~ 1/4" to 3",
more usually between about 1/2" and 2" thick. One advantage in preparing
the product of the present invention is that it can be prepared for outdoor
applications on the site as well as being capable of being prepared in
modules or sections in a plant. Usually the product is prepared by im-
mersing or embedding fibers in the molten plasticized sulfur and then
- removing a backing or o~her means which might be used to hold the fibers
or yarn elements in place when they are embedded in the molten plasticized
sulfur and during the solidification of the plasticized sulfur. Means for
implanting fibers into molten plasticized sulfur are also discussed in my
joint inventorship and commonly assigned United States Patent 3,944,452.
EXAMPLES
Example 1 -- Plasticized Sulfur Mastic as a Carpet Base
A plasticized sulfur mastic was prepared by heating a
mixture of 3 parts of dicyclopentadiene and 100 parts of molten sulfur
until there was a noticeable increase in viscosity. Next, 10 parts of talc
and 3 parts of glass fiber (milled to 1/8" lengths) were added and the
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whole mixture was stirred until it was homogenous. This material was then
; 20 poured onto a flat 12" x 18" area of ground covered with small-sized gravel
to a depth of 3/8". Before the sulfur mastic hardened, a sheared or cut-
pile indoor-outdoor carpet, made by tufting polypropylene yarn into a
polypropylene primary backing and without any latex or other secondary
backing, was laid on the mastic. When the mastic had hardened, a corner
of the backing
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was pried loose, and then the entire backing was pulled upward,
through the cut piles, leaving the tufts securely anchored in
the smooth, hard mastic surface. The finished installation had
the appearance of a grassy lawn.
One unexpected beneficial advantage of thc product
was the excellent adherence and retention of the polypropylene
fibers or yarn by the plasticized sulfur.
~xample 2--Non-Plasticized Sulfur ~lastic as a Carpet Base
(a) A small (4" x 4") piece of polypropylene tufted
o indoor-outdoor carpet was immersed upside down (about 1/4")
into a molten sulfur-glass fiber mixture 1/2" deep. When the
sulfur had hardened, the carpet backing was cut off, leaving a
grass-like structure held in place by the solidified sulfur-
glass fiber mixture.
(b) The same experiment was repeated except that the
glass fibers were replaced by sand. The results were the same.
The above experiment indicates that sulfur, with or
without an added material such as talc or sand or glass fiber,
can be used in the present invention instead of plasticized
. 2d sulfur. However, my other experimental work indicates that
plasticized sulfur performs better in the present invention.
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