U.S. patent application number 09/384351 was filed with the patent office on 2001-11-01 for large sized carbon black particles to reduce needed mixing energy of high hardness, stiff tire compositions.
Invention is credited to MCNUTT, JAMIE J., O'BRISKIE, WILLIAM J., SQUIRE, NICOLE L..
Application Number | 20010036993 09/384351 |
Document ID | / |
Family ID | 23516986 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010036993 |
Kind Code |
A1 |
MCNUTT, JAMIE J. ; et
al. |
November 1, 2001 |
LARGE SIZED CARBON BLACK PARTICLES TO REDUCE NEEDED MIXING ENERGY
OF HIGH HARDNESS, STIFF TIRE COMPOSITIONS
Abstract
A reinforced high viscosity rubber composition having improved
processability such as reduced mixing cycles contains large sized
particles of carbon black. The carbon black has low structure and a
low DBP absorption number as well as a low iodine number. The
rubber composition is useful in various tire rubber compositions
such as those requiring a high viscosity, for example an apex
rubber.
Inventors: |
MCNUTT, JAMIE J.;
(TALLMADGE, OH) ; SQUIRE, NICOLE L.; (CUYAHOGA
FALLS, OH) ; O'BRISKIE, WILLIAM J.; (UNIONTOWN,
OH) |
Correspondence
Address: |
JOHN H HORNICKEL
CHIEF INTELLECTUAL PROPERTY COUNSEL
BRIDGESTONE/FIRESTONE INC
1200 FIRESTONE PARKWAY
AKRON
OH
44317
|
Family ID: |
23516986 |
Appl. No.: |
09/384351 |
Filed: |
August 27, 1999 |
Current U.S.
Class: |
524/495 ;
106/472 |
Current CPC
Class: |
C08L 21/00 20130101;
C08K 3/04 20130101; C08K 3/04 20130101 |
Class at
Publication: |
524/495 ;
106/472 |
International
Class: |
C08K 003/04; C09C
001/44 |
Claims
What is claimed is:
1. A reinforced rubber composition, comprising: a high viscosity
rubber, and large particles of carbon black, said carbon black
particles having an iodine number of about 40 or less and a DBP
absorption of about 65 or less.
2. A reinforced rubber composition according to claim 1, wherein
the Mooney viscosity (ML.sup.1+4) is from about 30 to about 80, and
wherein the amount of said large particles of carbon black is from
about 5 to about 70 parts by weight per 100 parts by weight of said
rubber.
3. A reinforced rubber composition according to claim 2, wherein
said rubber is natural rubber, a rubber made from monomers of one
or more conjugated dienes having from 4 to 12 carbon atoms, a
rubber made from monomers of a conjugated diene having from 4 to 12
carbon atoms and a vinyl substituted aromatic having from 8 to 12
carbon atoms, or combinations thereof, wherein said DBP absorption
is from about 20 to about 55, and wherein said iodine number is
from about 3 to about 35.
4. A reinforced rubber composition according to claim 3, wherein
said rubber viscosity (ML.sup.1+4) is from about 40 to about 70,
wherein the amount of said carbon black particles is from about 10
to about 40 parts by weight per 100 parts by weight of said rubber,
wherein said DBP absorption is from about 30 to about 45, and
wherein said iodine number is from about 6 to about 25.
5. A reinforced rubber composition according to claim 1, wherein
said rubber composition is cured.
6. A reinforced rubber composition according to claim 4, wherein
said rubber composition is cured.
7. A reinforced tire rubber composition, comprising: a rubber and
an effective amount of large sized carbon black particles to reduce
the Mooney of (ML.sup.1+4) viscosity of said rubber composition
after blending but before cure.
8. A reinforced rubber composition according to claim 7, wherein
said effective amount of large sized carbon black is from about 5
to about 70 parts by weight per 100 parts by weight of said rubber,
wherein said large sized carbon black particles have a DBP
absorption of about 65 or less and an iodine number of about 40 or
less.
9. A reinforced rubber composition according to claim 8, wherein
said DBP absorption is from about 20 to about 55, and said iodine
number is from about 3 to about 35.
10. A reinforced rubber composition according to claim 9, wherein
said effective amount is from about 10 to about 40 parts by weight
per 100 parts by weight of said rubber, wherein said DBP is from
about 30 to about 45, wherein said iodine number is from about 6 to
about 25, and wherein said Mooney (ML.sup.1+4) viscosity is from
about 30 to about 80.
11. A reinforced rubber composition according to claim 7, wherein
said reinforced tire rubber composition is cured.
12. A reinforced rubber composition according to claim 10, wherein
said tire reinforced rubber composition is an apex rubber, and
wherein said apex rubber is cured.
13. A process for mixing a high viscosity tire rubber composition
comprising the steps of: adding large sized carbon black particles
to a rubber composition, said carbon black particles having a DBP
absorption of from about 20 to about 65 and an iodine number of
from about 3 to about 40; and mixing said large sized carbon black
particles and said rubber in a reduced number of mixing stages than
with normal sized carbon black to form a rubber composition having
a Mooney viscosity ML.sup.1+4) of from about 30 to about 80.
14. A process according to claim 13, wherein the amount of said
large sized carbon black is from about 5 to about 70 parts by
weight per 100 parts by weight of said rubber.
15. A process according to claim 14, wherein said carbon black has
a DBP absorption of from about 30 to about 45, an iodine number of
from about 6 to about 25, and wherein the amount of said large
carbon black particles is from about 10 to about 40 parts by weight
per 100 parts by weight of said rubber.
16. A process according to claim 13, including curing said rubber
composition.
17. A process according to claim 15, including curing said rubber
composition.
Description
FIELD OF INVENTION
[0001] The present invention relates to a high viscosity rubber
composition which has reduced mixing cycles due to the
incorporation of exceptionally large carbon black particles
therein.
BACKGROUND OF THE INVENTION
[0002] Heretofore, reinforced rubber compositions, especially for
tires, generally utilize conventional sized carbon black, which
typically resulted in good reinforcing properties. However, rubber
compositions having high viscosity required a large number of
remilling operations to reduce the viscosity thereof to an
acceptable level.
[0003] U.S. Pat. No. 5, 426,147 relates to rubber compositions
having reduced permeability to gases comprising rubber and
specified furnace carbon blacks.
[0004] U.S. Pat. No. 5,456,750 relates to furnace carbon blacks
that impart advantageous properties to rubber and plastic
compositions and may be utilized in place of lampblacks, thermal
carbon blacks and blends of carbon blacks. Also disclosed are
rubber and plastic compositions incorporating the carbon blacks
which exhibit advantageous combinations of compound processing and
physical performance properties.
[0005] U.S. Pat. No. 5,688,317 relates to carbon blacks that impart
advantageous properties to rubber and plastic compositions and may
be utilized in the place of lampblacks, thermal carbon blacks and
blends of carbon blacks. Also, disclosed are rubber and plastic
compositions incorporating the carbon blacks which exhibit the
advantageous combinations of compound processing and physical
performance properties.
SUMMARY OF INVENTION
[0006] It is an aspect of the present invention to use large sized
carbon black particles to reduce the number of mixing stages of
hard or stiff tire compositions without reducing the hardness,
stiffness, or other critical physical properties thereof. The
reinforced rubber compositions of the present invention thus
reduces mix energy usage. The compositions of the present invention
generally utilize large carbon particles characterized by low
crushed DBP absorption values as well as low iodine numbers.
DETAILED DESCRIPTION OF THE INVENTION
[0007] The rubber compositions of the present invention generally
contain one or more rubbers made from a conjugated diene having
from 4 to 12 carbon atoms and preferably from 4 to 8 carbon
atoms.
[0008] Examples of such dienes include butadiene (preferred),
isoprene (preferred), 2,3-dimethyl-1,3-butadiene;
2-methyl-1,3-pentadiene; 3,4-dimethyl- 1,3-hexadiene; 4,5-diethyl-
1, 3-octadiene; 3-butyl- 1,3-octadiene; phenyl-1,3-butadiene; and
the like.
[0009] Another class of rubbers which can be utilized in the
present invention are copolymers of the above-noted conjugated
dienes having from 4 to 12 carbon atoms with one or more vinyl
substitute aromatic compounds such as those having from 8 to 12
carbon atoms with specific examples including styrene,
alpha-methylstyrene, tertiary- butylstyrene, vinylnaphthalene, and
the like, with styrene-butadiene rubber being preferred. Another
preferred rubber compound is natural rubber, ie. that is rubber
which is derived from trees, which are generally grown in the
tropics.
[0010] The present invention is generally not applicable to
so-called "soft" rubbers. Such rubbers are generally classified as
being rubbers derived from ethylene and propylene, for example, EP
rubbers, rubbers which additionally include small amounts of a
conjugated diene such as EPDM rubbers, butyl rubber, rubbers made
from unconjugated diene monomers such as norbornene,
ethyl-norbornene, dicyclopentadiene rubber, other types of soft
rubbers such as various urethane rubbers, and the like.
[0011] According to the concepts of the present invention, it has
been found that the utilization of large sized carbon black
particles added to a so called hard rubber composition reduces the
number of mixing stages required and hence results in energy
savings. Such carbon blacks can generally be defined as being a low
structure carbon black and thus have low DBP absorption numbers
such as generally less than about 65, desirably to about 20 to
about 55, and preferably from about 30 to about 45. DBP absorption
can be determined in accordance with ASTM test number D-2414. The
large sized carbon black particles also have low iodine numbers
such as generally less than about 40, desirably from about 3 to
about 35, and preferably from about 6 to about 25. Such large
carbon black particles are commercially available from Cabot
Corporation as Regal 85, from Engineered Carbons as N990, from
Cancarb Ltd. as Thermax Floform, and from Columbian Sevalco Ltd. as
Servacard MT-N-990.
[0012] The large sized carbon black particles of the present
invention are desirably utilized in hard or stiff rubber
compositions, since they have been found to reduce the rubber
composition viscosity during mixing, although the end hardness of
the rubber composition is generally the same as that when the large
carbon black particles are not utilized. Such hard rubber
compositions after adding and blending all of the various additives
but before curing, generally have a Mooney viscosity ML.sup.1+4 of
generally from about 30 to about 80 and desirably from about 40 to
about 70. The hard rubber compositions generally contain natural
rubber, inasmuch as the same is generally harder than synthetic
rubbers, but contain very little oil, that is generally less than
20, often less than 15, and even less than 10 or nil parts by
weight per 100 parts by weight of rubber.
[0013] The masterbatching, mixing, remixing, remilling, etc.,
generally relate to a rubber composition containing the large sized
carbon black particles, stearic acid, zinc oxide, regular sized
carbon black particles, optionally a resin; optionally silica;
optionally a silica coupling agent; optionally various fillers such
as clay, for example, kaolin clay, and the like; and also
optionally a small amount of oil. After the necessary mixing stages
have been completed, various rubber additives are added and the
rubber composition is mixed a final time.
[0014] The final mixing stage is conducted by optionally further
adding one or more of the above-noted additives, as well as by
further adding other rubber additives. Additives typically added in
the final mixing stage include curing aids such as sulfur or sulfur
containing compounds; accelerators such as amines, disulfides,
guanidines, thioureas, thiazoles, thiurams, sulfenamides,
dithiocarbamates; oils such as aromatic, naphthenic, or paraffinic;
antioxidants and antiozonants such as various phenylenediamines;
various aliphatic acids such as stearic acid; zinc oxide; various
waxes such as micro crystalline waxes; various peptizers; and the
like.
[0015] The hard rubber compositions can be utilized in any of a
number of applications, such as in a tire where they are often
utilized for a tire bead, an abrasion resistant rubber layer which
resides on the tire bead, a chaffer strip, and the like. Such
rubbers are generally referred to in the art as apex rubbers.
Depending upon the actual end use, the amount of large carbon black
particles can generally range from about 5 to about 70 and
preferably from about 10 to about 40 parts by weight per 100 parts
by weight of total rubber.
[0016] Moreover, as noted above, the hard rubber formulations can
also contain additional regular carbon black, that is carbon black
which generally has an iodine number of from about 45 to about 100
and generally from about 70 to about 90 as well as a DBP absorption
number of generally from about 70 to about 140 and preferably from
about 90 to about 120. The amount of such carbon black will vary
depending upon the desired end use but generally is from about 20
to about 120, and desirably from about 75 to about 110 parts by
weight per 100 parts by weight of rubber.
[0017] The large sized carbon black particles have been found to
reduce the viscosity of the rubber composition during and after all
of the mixing stages (e.g., masterbatching, mixing, remixing) but
before cure of the rubber and still maintain the final hardness and
stiffness of the composition. That is, after all of the additives
have been added but before shaping into a tire bead strip, a chafer
strip, etc., and before cure, the rubber composition has a
viscosity less than a rubber composition containing only normal
sized carbon black.
[0018] Moreover, dramatic reductions in mixing cycles or the number
of remills required for preparation of a master batch and the final
stage of mixing are achieved. For example, in the preparation of a
bead filler rubber composition, which heretofore generally required
6 mixing stages, the number of remill stages, generally 3, has been
entirely eliminated. That is, instead of a first masterbatch stage,
a second masterbatch mixing stage, three remill stages and a final
mixing stage wherein various additives were added, the utilization
of the large sized carbon black resulted in only a first
masterbatch mixing stage, a second masterbatch mixing stage, and a
final additive mixing stage. As another example, in the preparation
of an abrasion rubber which heretofore required four mixing stages,
i.e. first masterbatch mixing stage, a second masterbatch mixing
stage, one remill stage, and a final additive mixing stage, all
that is required with the present invention is two mixing stages,
ie. an initial masterbatch mixing stage and a final additive mixing
stage. Elimination of the various mixing stages and the like result
in sizable reduction of the energy required and hence mixing
costs.
[0019] The present invention will be better understood by reference
to the following examples which serve to illustrate, not the limit
the present invention.
[0020] With respect to Tables I, II, and III, all formulations were
prepared in the following manner:
Masterbatch (MB) Preparation
[0021] The polymers, fillers, carbon blacks, oil, zinc oxide,
stearic acid, and resin were added to a Banbury. The fillers were
split between the first and second masterbatch for the conventional
mixed stock. The mixing time was from about 1.5 to about 2.5
minutes and the drop temperature was about 330.degree. F. to about
350.degree. F. This stock was then aged for a minimum of 4 hours
before the remill stage.
Remill(s)
[0022] All stock from the masterbatch mix stages were put into a
Banbury. The mixing time was from about 1.0 to about 2.0 minutes
and the drop temperature was from about 300.degree. F. to about
330.degree. F. The stock was then aged a minimum of 4 hours before
the final stage.
Final Stage Mixing
[0023] All antioxidants, ozonates, accelerators, sulfur, any
remaining zinc oxide, stearic acid, or resins, and the rubber from
the previous stage (masterbatch or remill), was added to a Banbury.
The mixing time was from about 60 about 80 seconds. The batch was
then dropped at a temperature of from about 190.degree. F. to about
220.degree. F.
1TABLE I (ABRASION) CONTROL EX. 1 1.sup.st MASTERBATCH PHR PHR BR
(Butadiene Rubber) 50.00 50.00 NR (Natural Rubber) 50.00 50.00
Large Sized Carbon Black - Type N660 -- 10.00 Regular Carbon Black
- Type N330 55.00 74.00 Stearic Acid 2.00 2.00 Oil 15.00 15.00 Zinc
Oxide 2.75 2.75 Total: 174.75 203.75 2Nd MASTERBATCH PHR PHR Normal
Sized Carbon Black - Type N330 23.00 -- TOTAL: 197.75 -- Remill 1
197.75 -- Sulfur 3.50 3.50 Accelerator 1.10 1.10 Wax 0.80 0.80
Antiozonant 1.00 1.00 Antioxidant 1.00 1.00 TOTAL: 205.15
211.15
[0024]
2 Number of Mix Stages 4 2 Mooney Viscosity ML1 + 4 52.1 54.5
Stress/Strain M50% RT (MPa) 1.2 1.2 Tensile RT (MPa) 18.0 18.2
Elongation % 315.0 314.0 Ring Tear Room Temperature 305.1 324.8
Rebound Room Temperature 55.6 55.2
[0025]
3 TABLE II (BEAD FILLER) CONTROL EX. 2 1.sup.st MASTERBATCH PHR PHR
NR (Natural Rubber) 100.00 100.00 Regular Carbon Black - Type N330
50.00 37.00 Large Sized Carbon Black Type N660 -- 25.00 Zinc Oxide
5.00 5.00 Stearic Acid 1.50 1.50 Resin 2.00 2.00 TOTAL:: 158.50
170.50 2.sup.Nd MASTERBATCH PHR PHR Normal Sized Carbon Black -
Type N330 30.00 20.00 TOTAL: 188.50 190.50 Remill 1 188.50 --
Remill 2 188.50 -- Remill 3 188.50 -- Zinc Oxide 5.00 5.00 Stearic
Acid 1.50 1.50 Resin 9.00 9.00 Sulfur 10.00 10.00 Accelerator 1.00
1.00 TOTAL: 215.00 217.00
[0026]
4 Number of Mix Stages 6 3 Mooney Viscosity ML1 + 4 55.8 51.2
Stress/Strain M50% RT (MPa) 4.4 4.2 Tensile RT (MPa) 10.6 9.8
Elongation % 128.8 145.9 Ring Tear Room Temperature 96.5 91.4
Rebound Room Temperature 40.2 42.4
[0027]
5 TABLE III (BEAD FILLER) CONTROL EX. 3 1.sup.st MASTERBATCH PHR
PHR NR (Natural Rubber) 70.00 70.00 Styrene-Butadiene Rubber 30.00
30.00 Regular Carbon Black - Type N330 70.00 65.00 Large Sized
Carbon Black Type N660 -- 38.00 Zinc Oxide 2.00 2.00 Oil 7.00 7.00
Stearic Acid 1.50 1.50 Resin 5.00 5.00 TOTAL: 185.50 218.50
2.sup.Nd MASTERBATCH PHR PHR Normal Sized Carbon Black - Type N330
33.00 -- TOTAL: 218.50 -- Remill 1 218.50 -- Remill 2 218.50 --
Resin 9.00 9.00 Sulfur 3.00 3.00 Accelerator 1.00 1.00 TOTAL:
231.50 231.50
[0028]
6 Number of Mix Stages 5 2 Mooney Viscosity ML1 + 4 47.8 48.0
Stress/Strain M50% RT (MPa) 4.1 3.7 Tensile RT (MPa) 14.2 15.2
Elongation % 275.0 332.0 Ring Tear Room Temperature 298.0 263.0
Rebound Room Temperature 39.7 40.8
[0029] As apparent from the tables, rubber compositions utilizing
large sized carbon black particles according to the present
invention result in an unexpected and drastic reduction in the
total number of mixing stages.
[0030] While in accordance with the patent statutes, the best mode
and preferred embodiment have been set forth, the scope of the
invention is not limited thereto, but rather by the scope of the
attached claims.
* * * * *