Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to an improved sound deadening material.
Damping of vibration in thin sheet material such as the sheet metal
floor pans of automobiles is important to reduce noise level. Presently, .
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vibration damping of metal floor pans is secured by adhering a composition
sheet to the metal by placing the composition sheet on the metal floor pan
before the automobile body goes through heating ovens employed in finishing
the body. The heat of the oven softens the composition sheet so that it wilts
into conformity with the floor pan and adheres to the metal surface. A variety
of heat softenable compositions, usually mixtures of bitumen, fillers and/or
fibers, and a natural or synthetic hydrocarbon rubber, e. g., a butadiene
styrene copolymer synthetic rubber, have been tried for this use. .
Tests established for acceptance of materials for this use by automobile
manufacturers require that the sheet material wilt into conformity with and
adhere to the metal of the floor pans at temperatures at least as low as temp- :
eratures reached in the heating ovens during finishing of the body, but that
flowing or running of the material at substantially higher temperatures shall
not exceed a limited value. These tests can be met by using substantial
proportions of a hydrocarbon rubber in the compositior . ~owever, use of
such proportions of rubker, which is much more expensive than bitumen, :
markedly increases the cost of the sheet material and is believed to reduce the : : . `
vibration damping efficiency.
It is an object of the present invention to provide a less expensive sound . ~ .
deadening sheet material capable of meeting the temperature response require-
ments for use in automobiles.
To this end, and in accordance with a feature of the present invention,
there is provided a sheet composition based on bitumen and filler in which .
resistance to undesired high temperature flow together with good conformability
and adhesion properties are secured through combination and interaction of
a limited amount of a vulcanized vegetable oil with the
bitumen.
According to a broad aspect of the present
invention, there is provided a sound deadener sheet softenable
by heat to wilt into conformity and adhesive engagement with
a contoured metal surface but resistant to running and flow
at higher temperatures. The sheet is formed of a mixture of
mineral filler and a binder. The binder comprises about 45%
to about 70% by weight of asphaltic bitumen from the class
consisting of natural asphalt and residue from the distilla-
tion of petroleum, from about 5% to about 20% by weight of
an elastomeric modifier compatible with the asphaltic bitumen
and from about 1.5% to about 3.5% of the solid, non-thermo-
plastic product of reaction of vegetable unsaturated oil
with sulfur, sulfur monochloride or sulfur dichloride coact-
ing with the asphaltic bitumen to prevent running and flow
of the sheet at higher temperatures. The weight percentages
are based on the weight of the binder. -~
The Figure is an angular elevational view of a
contoured metal sheet used for testing thermal properties of
sound deadener sheet material.
In accordance with the present invention, I have
provided a filled bituminous sound deadener sheet having ;
an unexpected combination of characteristics in heated
condition particularly fitting it for union with shaped
metal, such as in use of the sheet material as a sound
deadener for automobile floor pans. These unexpected proper-
ties are secured through combination of relatively small
proportions of a vulcanized vegetable oil with bitumen as
binder for mineral filler. The binder preferably also
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includes an elastomeric modifier to reduce brittleness and
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improve elasticity and resistance to tearing.
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Vulcanized vegetable oil is a solid, non-thermo-
plastic product of reacting vegetable unsaturated oil such
as linseed oil, cottonseed oil, soybean oil or others with
sulfur or with sulfur derivatives such as sulfur monochloride,
sulfur dichloride, and the like. These materials are
commercially available for example under the registered
trademark "FACTICE" from the American Cyanamid Company. The
product from reaction of the vegetable oil with sulfur is
preferred for the present use. These vulcanized oils are
most commonly used as extenders, processing aids or
plasticizers for natural and synthetic rubbers. However, ;
in the present case, the vulcanized oil coacts with the
bitumen to provide, in the mineral-filled bitumen sound
deadener sheet of the present invention, a unique combination
of good heat wilting characteristics for conforming and
bonding to a ribbed and/or curved metal plate, and of
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resistance to running or flow at high temperatures.
The bitumens which can be employed in the binderfor compositions of the present invention are preferably
asphaltic and may be either natural asphalt or residue from
the distillation of petroleum. Thé asphaltic bitumens are
commercially available in penetration values up to about
300 as determined by ASTM method D-5-73 at 77 F. Softening
points (Ball and Ring), as determined by ASTM method D-36-70
should be in the range of from about
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60F. to about 110F., preferably from about 60F. to about
80F.
~Iydrocarbon oil is preferably included in relatively
small percentages as a component of -the binder to improve
mixing of the bitumen with the mineral filler. Also, it has
been found that addition of gilsonite to the composition
materially improves the breaking strength and tear strength
of the sound deadener sheet.
Elastomeric modifiers for inclusion ~n the compositions
of the present invention may be hydrocarbon elastomers and co-
polymers of ethylene with non-hydrocarbon monomers which may
be known for inclusion in bituminous compositions.
Hydrocarbon rubber-like elastomers useful as modifiers
for combination with bitumen and vulcanized vegetable oil in
the binder for the sound deadening composition may be natural
rubber, synthetic polymer Or copolymer rubbers or reclaim
rubber. Suitable synthetic rubbers include styrene-butadiene
copolymer synthetic rubbers, butadiene-styrene block copolymers,
e.g. "Kraton"* 1107 manufactured by the Shell Chemical Co.,
butyl rubber, poLyisobutylene, ethylene-propylene copolymers
t~PM), ethylene-propylene-diene terpolymers (EPDM) and mix-
tures of these. A preferred range of Mooney values is from
20 to 35.
Preferred ethylene copolymers for use as elastomeric
modifiers include bitumen-soluble copolymers containing from
about 40% to about 98% preferably from about 60% to about 90%
by weight of ethylene with from about 60% to about 2% pre-
ferab~y from about 40% to about 10% by weight of a mono-unsat-
urated polymerizable compound such as a lower alkyl, i.e. 1
to 6 carbon atoms, acrylate or methacrylate.
Gilsonite which also forms a component of the binder is
a natural hard thermoplastic hydrocarbon resin having a melt-
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j *Registered Trademark
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ing point of from 270F. to 280F. and a penetration at
77F. of less than 1~
A preferred formulation offering special advantages in
the binder of the present sound deadener, involves combinin~ .
in balanced ranges of proportions, bitumen, elastomer modi-
fier and gilsonite together with a small but effective amount
of vulcanized vegetable oil to control the softening and .
flow properties together with good sound deadening efficiency ;. ...
and low cost~ Based on the~total weight of the binder, useful - .
proportions in terms of weight percentages will include from ~ .
45% to 70%, preferably about 50% to 60% by weight of bitumen,
from about 50% to about 20%, preferably from about 10% to :
about 15% of elastomeric modifier, from about 15% to about
20% of gilsonite, and from about 1.5% to about 3.5%, prefer-
ably from about 2% to about 2.5% of vulcanized vegetable oil. ; ..... ... :
Mineral filler for combination with the binder may be .-
any of a variety of finely divided inorganic materials such as
ground limestone, suitably a dolomitic limestone, whiting, :~
barytes, calcium carbonate, clay, slate, mica and so on. The
particle size should be such that about 80% will pass a 200
mesh ,screen and none will be held on a 35 mesh screen~ The
particles of mineral filler are of a size less than that which .
will pass a 325 mesh screen. .
The filler content of the sound deadener sheet of the
present invention may be between about 60% to about 85% pre-
ferably from about 75% to about 85% by weight and the binder
correspondingly from about 40% to about 15% preferably from
about 25% to about 15% by weight based on the weight of the
sheet. . : .
The sheet may be compounded in any conventional ~anner
as by mixing together the bitumen, elastomeric modifier,
gilsonite and vulcanized vegetable oil in a heated ves~el
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and then adding the mineral filler to the hot mixture and
mixing to uniformity. The mixture is then formed into a
sheet by calendar rolls or other suitable deviceO For use
as a sound deadener for sheet metal floor pans for automo- : :
blles, sheets are preferably from about 0.05 lnch to about
0.1 inch in thickness.
The sound deadener sheet for use with an automobile
floor pan is merely laid on the upper surface of the floor
pan and is required to soften and wilt into conformity with
the contour of the floor pan during the heating used in :`
flnishing the automobile body, but must also not be softened
to a condition in which lt runs excesslv21y so as to lose
its uniformity and to run or flow past :
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the areas where it is desired. Tests for acceptance of sound deadener sheet
material involve laying a 2 X 10" strip 10 of the sound deadener sheet across
a metal sheet 12 contoured as shown in the Figure and heating the assembly
to 275F. for one-half hour. As shown in the Figure, the metal sheet 12 has
a flat, horizontally disposed first section 14, a section 16 extending downward :
at right angles to the first section and a further horizontally disposed section
18. The section 18 is formed with small grooves 20. It is required that after
the heating, the strip 10 has sagged or wilted from its original position and
flat shape shown in broken lines in the Figure into conformity not only with
10 the downwardly angled section 16 but also with the small grooves 20 so that
there is not more than a 1/16" gap between the strip 10 and the contoured metal
section 12 at any point. A further test to establish that the sheet does not flow
or run excessively involves disposing a 2 X 6" strip 22 on the flat portion 14 ~ -
of the contoured metal surface with a portion oE the strip, as shown in broken
lines in the Figure, extending beyond the edge that flat portion 14 by an amount
which would bring the edge 26 against an upper score mark 28, on the down-
wardly extending portion 30 when the strip 22 has bent downwardly into engage-
ment with the vertical portion 16 of the metal sheet 12. It is required that on
heating the sample to 400F. the downwardly bent portion 30 of the strip 22
20 must not flow more than 3/8" in one hour, i. e. must not have flowed down
to the lower score mark 32 on the vertical portion 16 of the metal surface.
Additional requirements are that the sheet have a breaking tensile strength
of at least 0.1 pound per mil thickness and inch width.
The following examples are given to aid in understanding the invention
but it i9 to be understood that the invention is not restricted to the particular
procedures, materials or the like of the examples.
EXAMPLE ONE
The following is a formula of a sound deadener sheet for use in
connection with an automobile floor pan.
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Finely divided dolomitic limestone 80
CaO 0. 6
Butadiene styrene copolymer rubber
(Mooney viscosity 27 to 35) 3.2
Gilsonite 4 5
Low melting point bitumen 11.2
Vulcanized vegetable oil (Factice #11 Brown) 0. 5
The bitumen was a commercial product known as 22 L, obtained from
Pioneer Division of Witco Chemicals Co. having a :Ball and Ring melting point
of about 80F. and a nominal penetration value of 300 at 77F. by ASTM method
of D-5-73. The finely divided dolomitic limestone had a particle si~e such
that about 80% will pass a 200 mesh screen and none will be retained on a 35
mesh screen, the screens being U. S. Standard Sieve. -
The butadiene styrene copolymer rubber, gilsonite and vulcanized
vegetable oil were introduced into an internal mixer sold under the trademark ~:
BANE3URY and worked together at 320F. At this point, l/2 of the bitumen
and l/2 of the finely divided dolomitic limestone were added and when they
had been thoroughly mixed in, the remainder oE the components were added
and thoroughly mixed in. The mixture was discharged from the mixer and
sheeted out between the rolls of a calender to a thickness of 0 . 070" + 0 . 005" . ~;
The sheet material was subjected to the conformity and flow tests described
above in the specification and successfully passed these tests.
A composition identical with the formula given above except that it did
not include vulcanized vegetable oil was prepared and Eormed into a sheet.
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When the sheet was subjected to conformit~ and flow tests, it was folmd that ~ :
the material flowed badly during the 400F. portion of the test. ~
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E~ aPLE TWO
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The following formula was prepared for use as a sound deadener sheet
- for an automobile floor pan.
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Parts by weiqht
Finely divided dolomitic limestone 79.7
CaO 0.6 -
Ethylene propylene diene terpolymer (EPDM) 1.0
Gilsonite 3.0
Intermediate melting point bitumen 15.2
Vulcanized vegetable oil 0.5
The composition was mixed and formed into a sheet follow-
ing the procedure of Example One. The resulting sheet mater-
ial was subjected to the conformity and flow tests described
above in the specification and successfully passed these
tests.
EXAMPLE THREE ;
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The following formula was prepared for use as a sound
deadener sheet material.
Parts by weiqht
Finely divided dolomitic limestone
(200 mesh) 80.5
CaO 0.6
Ethylene-propylene copolymer 3.2
Vulcanized vegetable oil 0.5
Low melting point bitumen 11.2
Gilsonite 4.0
The ethylene-propylene copolymer was the commercial
product known as Vistalon 404*, a product of Enjay Chemical -
Company having an ethylene content of about 40%, a propylene
content of about 60% and a Mooney value of 35 to ~5 and the
bitumen was the same bitumen material used in Example One.
The composition was mixed and formed into a sheet follow-
ing the procedure of Example One. The re.sulting sheet was
subjected to the conformity and flow tests described above
in the specification and successfully passed these tests.
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*Registered Trademark
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