U.S. patent application number 11/029854 was filed with the patent office on 2005-06-02 for rubber compositions and articles thereof having improved metal adhesion and metal adhesion retention with bright steel.
Invention is credited to Hergenrother, William L., Ravagnani, Frederick J., Ravagnani, Roberta A., Schonfeld, Steven E..
Application Number | 20050119383 11/029854 |
Document ID | / |
Family ID | 32593217 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050119383 |
Kind Code |
A1 |
Hergenrother, William L. ;
et al. |
June 2, 2005 |
Rubber compositions and articles thereof having improved metal
adhesion and metal adhesion retention with bright steel
Abstract
A vulcanizable rubber composition having improved metal adhesion
and metal adhesion retention properties with bright steel, the
improvement wherein from about 0.1 to about 10 parts by weight of a
compound selected from the group consisting of aminosilanes and
mercaptosilanes and mixtures thereof, per 100 parts of the rubber
component in the rubber composition is incorporated into the rubber
composition prior to curing. Structural components for a pneumatic
tire contain a cured rubber composition, having from about 0.1 to
about 10 parts by weight of a compound selected from the group
consisting of aminosilanes and mercaptosilanes and mixtures thereof
per 100 parts of the rubber component in the rubber composition,
incorporated into the rubber compounds prior to curing. A method
for improving metal adhesion and metal adhesion retention
properties between a vulcanizable rubber composition and bright
steel comprises the step of incorporating from about 0.1 to about
10 parts by weight of a compound selected from the group consisting
of aminosilanes and mercaptosilanes and mixtures thereof per 100
parts of the rubber component in the rubber composition into the
rubber composition prior to curing.
Inventors: |
Hergenrother, William L.;
(Akron, OH) ; Schonfeld, Steven E.; (Akron,
OH) ; Ravagnani, Frederick J.; (Uniontown, OH)
; Ravagnani, Roberta A.; (Akron, OH) |
Correspondence
Address: |
Chief Intellectual Property Counsel
Bridgestone Americas Holding, Inc. - Law Dept.
1200 Firestone Parkway
Akron
OH
44317-0001
US
|
Family ID: |
32593217 |
Appl. No.: |
11/029854 |
Filed: |
January 5, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11029854 |
Jan 5, 2005 |
|
|
|
10323458 |
Dec 18, 2002 |
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Current U.S.
Class: |
524/262 |
Current CPC
Class: |
C08K 5/54 20130101; C08K
5/54 20130101; Y10T 428/31692 20150401; C08L 21/00 20130101 |
Class at
Publication: |
524/262 |
International
Class: |
C08K 005/04 |
Claims
1-9. (canceled)
10. A method of providing a composite comprising steel
reinforcement adhered to rubber stock, comprising: a) providing a
blended composition from ingredients that comprise at least one
rubber, particulate filler, a sulfur curing agent, and a silane
component comprising at least one of an aminosilane and a
mercaptosilane; b) forming a layer of rubber stock from said
blended composition; and c) incorporating steel reinforcement into
said rubber stock to provide a reinforced composite, said steel
reinforcement having at least some of its surface area being
untreated, wherein said silane component acts to bond said at least
one rubber to said steel reinforcement in at least the untreated
surface area.
11. The method of claim 10 wherein said blended composition is
provided from ingredients that comprise, per 100 parts of said at
least one rubber, from 0.1 to about 10 parts by weight of said
silane component.
12. The method of claim 11 wherein said blended composition is
provided from ingredients that comprise, per 100 parts of said at
least one rubber, from 0.5 to about 5 parts by weight of said
silane component.
13. The method of claim 12 wherein said blended composition is
provided from ingredients that comprise, per 100 parts of said at
least one rubber, up to about 2 parts by weight of said silane
component.
14. The method of claim 10 wherein said blended composition is
provided from ingredients that comprise, per 100 parts of said at
least one rubber, from about 5 to about 100 parts by weight carbon
black.
15. The method of claim 14 wherein said blended composition is
provided from ingredients that further comprise, per 100 parts of
said at least one rubber, up to about 80 parts by weight of at
least one additional filler.
16. The method of claim 10 wherein said steel reinforcement is in
the form of at least one of wire, cable, cord, and filament.
17. The method of claim 10 wherein said silane component is added
to said blended composition after the other ingredients have been
mixed.
18. The method of claim 10 wherein said steel reinforcement
comprises low carbon steel.
19. The method of claim 10 further comprising curing said
reinforced composite so as to provide a vulcanized rubber stock
article.
20. A reinforced composite comprising steel reinforcement embedded
in a rubber stock, said steel reinforcement comprising at least a
portion of its surface area that is not treated and said rubber
stock being derived from a blended composition that comprises at
least one rubber, reinforcing filler, a sulfur curing agent, and a
silane component comprising at least one of an aminosilane and a
mercaptosilane, said silane component acting to bond said at least
one rubber to said steel reinforcement in at least its untreated
surface area.
21. The reinforced composite of claim 20 wherein said blended
composition is provided from ingredients that comprise, per 100
parts of said at least one rubber, from 0.1 to about 10 parts by
weight of said silane component.
22. The reinforced composite of claim 21 wherein said blended
composition is provided from ingredients that comprise, per 100
parts of said at least one rubber, from 0.5 to about 5 parts by
weight of said silane component.
23. The reinforced composite of claim 22 wherein said blended
composition is provided from ingredients that comprise, per 100
parts of said at least one rubber, up to about 2 parts by weight of
said silane component.
24. The reinforced composite of claim 20 wherein said blended
composition is provided from ingredients that comprise, per 100
parts of said at least one rubber, from about 5 to about 100 parts
by weight carbon black.
25. The reinforced composite of claim 24 wherein said blended
composition is provided from ingredients that further comprise, per
100 parts of said at least one rubber, up to about 80 parts by
weight of at least one additional filler.
26. The reinforced composite of claim 25 wherein said at least one
additional filler comprises silica.
27. The reinforced composite of claim 20 wherein said steel
reinforcement is in the form of at least one of wire, cable, cord,
and filament.
28. The reinforced composite of claim 20 wherein said steel
reinforcement comprises low carbon steel.
29. The reinforced composite of claim 20 wherein said rubber stock
is vulcanized.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention is directed toward improving the
adhesion and adhesion retention between a rubber composition and
metallic reinforcement cord, such as steel wire and cable which is
embedded in the rubber stock. Flat sheets or strips of such stocks,
reinforced with metal or fibers, are utilized as plies or other
components in the manufacture of tires, repair stocks for
retreading tires, conveyor belts, hoses and the like and are
referred to in the art as rubber skim stocks. Skim refers to a
relatively thin layer or coating of the rubber over the
reinforcement filaments or cords. Greater thicknesses of rubber are
also bonded to metal in other instances such as motor mounts and
golf club shafts and these would not be termed skim stocks.
[0002] In the manufacture of the foregoing rubber articles,
particularly steel-belted bias and radial tires, it has become
common to reinforce the rubber skim stock material with steel wire
or cable. One of the more important uses for a metallic reinforced
rubber is as a belt where one or more of these belts are
substantially circumferentially oriented beneath the tread stock to
maintain the integrity and shape of the tire during inflation and
subsequent load. Other areas where metal reinforced rubber skim
stock may be utilized is in the body ply, bead or chafer of a
tire.
[0003] There are many well-known methods for promoting adhesion
between vulcanizable rubber and steel reinforcement cords. For
instance, steel reinforcement cords are commonly plated with
compositions that are designed to promote and maintain adhesion to
vulcanized rubber. This method is generally successful in promoting
adhesion to vulcanized rubber wherever the surface plating contacts
the vulcanized rubber. However, during construction of a tire,
plated steel reinforcement cords are typically cut to fixed
lengths, and the cutting process leaves a bright steel core exposed
at the cross sections where cutting has occurred. As a result, the
exposed bright steel core lacks the surface coating and therefore
will not adhere to tires vulcanized rubber of the tire, which could
diminish tire performance. There is, therefore, a need for a method
that promotes adhesion between a bright steel surface and
vulcanized rubber.
[0004] In order to promote adhesion between rubber and ferrous
metals it is known to employ a variety of metallic salts or
complexes or other additives as coatings to the metal or as an
ingredient in a rubber composition.
[0005] Thus, while others have sought to enhance adhesion between
rubber compositions and bright steel by employing materials such as
cobalt para-aminobenzoate and para-aminobenzoic acid in the stock,
the art of which we are aware has not disclosed the exclusive use
of the silane compounds set forth hereinbelow in a vulcanizable
rubber stock to increase adhesion properties between rubber and
metallic reinforcement, particularly bright steel.
SUMMARY OF THE INVENTION
[0006] The present invention provides a vulcanizable rubber
composition having improved metal adhesion and metal adhesion
retention properties with bright steel, the improvement wherein
from about 0.1 to about 10 parts by weight of a compound selected
from the group consisting of aminosilanes and mercaptosilanes and
mixtures thereof per 100 parts of the rubber component in the
rubber composition is incorporated into the rubber composition
prior to curing.
[0007] The present invention also provides a structural component
for a pneumatic tire containing a cured rubber composition having
improved metal adhesion and metal adhesion retention properties
with bright steel, the improvement wherein from about 0.1 to about
10 parts by weight of a compound selected from the group consisting
of aminosilanes and mercaptosilanes and mixtures thereof per 100
parts of the rubber component in the rubber composition is
incorporated into the rubber composition prior to curing.
[0008] Finally, a method for improving metal adhesion and metal
adhesion retention properties between a vulcanizable rubber
composition and bright steel is provided comprising the step of
incorporating from about 0.1 to about 10 parts by weight of a
compound selected from the group consisting of aminosilanes and
mercaptosilanes and mixtures thereof per 100 parts of the rubber
component in the rubber composition into the rubber composition
prior to curing.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0009] To illustrate our invention, a typical example of a rubber
component with metallic reinforcement embedded therein was chosen.
In particular, the example used to demonstrate the invention was a
rubber skim stock which is suitable for the preparation of rubber
articles such as tires. Adhesion between this stock with steel
reinforcement subsequent to vulcanization was measured and has also
been presented hereinbelow.
[0010] Both synthetic and natural rubber may be employed within the
vulcanizable rubber compositions of the present invention. These
rubbers, which may also be referred to as elastomers, include,
without limitation, natural or synthetic poly(isoprene) with
natural polyisoprene being preferred, and elastomeric diene
polymers including polybutadiene and copolymers of conjugated diene
monomers with at least one monoolefin monomer. Suitable
polybutadiene rubber is elastomeric and has a 1,2-vinyl content of
about 1 to 3 percent and a cis-1,4 content of about 96 to 98
percent. Other butadiene rubbers, having up to about 12 percent
1,2-content, may also be suitable with appropriate adjustments in
the level of other components, and thus, substantially any high
vinyl, elastomeric polybutadiene can be employed. The copolymers
may be derived from conjugated dienes such as 1,3-butadiene,
2-methyl-1,3-butadiene-(iso- prene), 2,3-dimethyl-1,2-butadiene,
1,3-pentadiene, 1,3-hexadiene and the like, as well as mixtures of
the foregoing dienes. The preferred conjugated diene is
1,3-butadiene.
[0011] Regarding the monolefinic monomers, there include vinyl
aromatic monomers such as styrene, alpha-methyl styrene, vinyl
naphthalene, vinyl pyridine and the like as well as mixtures of the
foregoing. The copolymers may contain up to 50 percent by weight of
the monoolefin based upon total weight of copolymer. The preferred
copolymer is a copolymer of a conjugated diene, especially
butadiene, and a vinyl aromatic hydrocarbon, especially styrene.
Preferably the diene polymer content of the rubber compound can
comprise up to about 35 percent by weight in styrene-butadiene
random copolymer, preferably 15 to 25 percent by weight.
[0012] The above-described copolymers of conjugated dienes and
their method of preparation are well known in the rubber and
polymer arts. Many of the polymers and copolymers are commercially
available. It is to be understood that practice of the present
invention is not to be limited to any particular rubber included
hereinabove or excluded.
[0013] The rubber polymers used in practice of the present
invention can comprise either 100 parts by weight of natural
rubber, 100 parts by weight of a synthetic rubber or blends of
synthetic rubber or blends of natural and synthetic rubber such as
75 parts by weight of natural rubber and 25 parts by weight of
polybutadiene. Polymer type, however is not deemed to be a
limitation to the practice of the instant invention.
[0014] The vulcanizable rubber compounds of the present invention
contain conventional filler materials. Typical filler materials
include reinforcing fillers normally used in rubber formulations
such as carbon blacks, talcs, silica and other finely divided
mineral materials. Carbon black and silica are particularly
preferred. Silica and other filler materials excluding carbon black
are optionally compounded with elastomers in amounts ranging from 0
to about 80 parts by weight, per 100 parts of rubber (phr).
[0015] Generally, the elastomers are compounded with carbon black
in amounts ranging from about 5 to about 100 parts by weight, per
100 parts of rubber (phr), with about 5 to about 80 phr being
preferred and from about 40 to about 70 phr being more preferred.
Mixtures of fillers including carbon black can be employed in the
foregoing amounts. The carbon blacks may include any of the
commonly available, commercially-produced carbon blacks but those
having a surface area (EMSA) of at least 20 m.sup.2/g and more
preferably at least 35 m.sup.2/g up to 200 m.sup.2/g or higher are
preferred. Surface area values used in this application are those
determined by ASTM test D-1765 using the cetyltrimethyl-ammonium
bromide (CTAB) technique.
[0016] Among the useful carbon blacks are furnace black, channel
blacks and lamp blacks. More specifically, examples of the carbon
blacks include super abrasion furnace (SAF) blacks, high abrasion
furnace (HAF) blacks, fast extrusion furnace (FEF) blacks, fine
furnace (FF) blacks, intermediate super abrasion furnace (ISAF)
blacks, semi-reinforcing furnace (SRF) blacks, medium processing
channel blacks, hard processing channel blacks and conducting
channel blacks. Other carbon blacks which may be utilized include
acetylene blacks. Mixtures of two or more of the above blacks can
be used in preparing the carbon black products of the invention.
Typical values for surface areas of usable carbon blacks are
summarized in the following TABLE I.
1TABLE I Carbon Blacks ASTM Surface Area Designation (m.sup.2/g)
(D-1765-82a) (D-3765) N-110 126 N-220 111 N-339 95 N-330 83 N-343
90 N-550 42 N-660 35
[0017] The vulcanizable rubber compounds are cured by sulfur and
thus, a sulfur curing agent, such as sulfur or a sulfur donor is
required. Minimally, at least about 2 phr of sulfur, or an
equivalent amount of sulfur donor, is added to the compound to
provide high modulus. In the present invention, addition of a
sulfur in oil blend is generally preferred, with the mixture
comprising about 80 percent by weight of sulfur and 20 percent by
weight of oil. The oils employed are conventional rubber processing
oils. Conventional cure accelerators are also employed to provide
fast modulus generation during cure. The vulcanizable rubber
compounds also include from about 1 to 3 phr of an antioxidant and
an antiozonant of conventional types, (employed in the usual
amounts) to impart good heat resistance.
[0018] The compounds of the present invention can contain
conventional antioxidants, antiozonants and accelerators, as is
shown in the exemplary formulations which follow. It is to be
understood that such components are well known to those skilled in
the art and thus, the present invention is not limited to the use
of any particular antioxidants, antiozonants or accelerators, or
amounts thereof. Similarly, practice of the present invention is
also not limited to the specific formulations presented
hereinbelow.
[0019] The additive component utilized in the practice of the
present invention includes silane compounds such as the
aminosilanes (3-aminoalkyl triethoxy silane, where the alkyl is C2
to C8) and the mercaptosilanes (3-aminomercapto triethoxy silane)
as well as mixtures thereof. The amino groups can be 1.degree.,
2.degree. or 30.degree. and include alkyl aminos having up to about
eight carbon atoms. Both silane compounds can be obtained from the
3-chloropropyl trichloro silane.
[0020] The silane compounds can be incorporated into the rubber
skim stock in amounts ranging from about 0.1 to about 10 parts by
weight per hundred parts of rubber (phr). Preferably, silane
compounds are incorporated into the rubber skim stock in amounts
ranging from about 0.5 to about 5 phr.
[0021] Silane compounds can be compounded into the rubber
composition by using conventional techniques such as banbury batch
processing, single or twin screw extrusion, continuous mixing,
co-kneader extrusion, and mill mixing. Of these techniques, banbury
batch processing is preferably employed.
[0022] Any conventional steel can be employed in practicing the
present invention; nonlimiting examples include low, medium, and
high-carbon grades of steel. Low carbon steel is preferably
employed in practicing the present invention.
[0023] In the tests which follow, four rubber skim stock
materbatches, A-D, were, prepared which did not contain the
adhesion promotion silane compounds of the present invention.
Masterbatch A contained resorcinol as an adhesion promoter.
Masterbatch B contained no adhesion promoting components.
Masterbatch C contained hydrocarbon resin and Manobond C as
adhesion promoters. Masterbatch D contained resorcinol, hydrocarbon
resin and Manobond C as adhesion promoters. Manobond C is a cobalt
and boron containing additive commercially available from Wyrought
and Loser, Inc., Trenton, N.J. Improved adhesion in a natural
rubber stock containing Manobond C has been demonstrated in U.S.
Pat. No. 4,267,079. The formulations of Masterbatches A-D are
presented in Table I with all parts given on the basis of parts per
hundred parts of rubber (phr) by weight.
2TABLE II Skim Stock Masterbatchs A B C D Natural Rubber 100 100
100 75 Polybutadiene -- -- -- 25 Carbon black 50 50 55 40 Silica --
-- -- 10 Zinc Oxide 7.5 7.5 7.5 4.0 Stearic Acid 0.5 0.5 0.5 1.0
Santoflex DD.sup.a 2.0 2.0 2.0 -- Aromatic oil -- -- 2.0 --
Santoflex 13.sup.b 1.0 1.0 1.0 1.0 Resorcinol 2.0 -- -- 2.5
Hydrocarbon resin -- -- 2.0 5.0 Manobond.sup.c -- -- 2.0 3.5 TOTAL
163 161 171 167 .sup.a)6-dodecyl-1,2-dihyd- ro-2,2,4-trimethyl
quinoline .sup.b)N-(1,3-dimethylbutyl)-N'-phen-
yl-p-phenylenediamine .sup.c)Petroleum derived aliphatic
hydrocarbon resin
[0024] Each masterbatch was thereafter fully compounded with cure
packages and the adhesion promoting silane compounds of the present
invention. Masterbatch A was utilized to formulate Example Nos.
1-4. Example Nos. 1 and 2 contained, respectively, 0.5 and 2 phr of
aminosilane (3-aminopropyl triethoxy silane), while Example Nos. 3
and 4 contained, respectively, 0.5 and 2 phr of mercaptosilane
(3-aminomercapto triethoxy silane). Masterbatch B was utilized to
formulate Example Nos. 5-8. Example Nos. 5 and 6 contained,
respectively, 0.5 and 2 phr of aminosilane, while Example Nos. 7
and 8 contained, respectively, 0.5 and 2 phr of mercaptosilane.
Masterbatch C was utilized to formulate Example Nos. 9-12. Example
Nos. 9 and 10 contained, respectively, 0.5 and 2 phr of
aminosilane, while Examples 11 and 12 contained, respectively, 0.5
and 2 phr mercaptosilane. Masterbatch D was utilized to formulate
Example Nos. 13-16. Example Nos. 13 and 14 contained, respectively,
0.5 and 2 phr of aminosilane, while Example Nos. 15 and 16
contained, respectively, 0.5 and 2 phr of mercaptosilane.
[0025] It is to be understood that the foregoing formulations of
the masterbatches, A-D, and subsequent rubber skim stocks have been
presently solely to enable those skilled in the art to evaluate
practice of the invention. As such, the present invention is not to
be limited only to these specific formulations.
[0026] The 16 compositions were each used to build T-adhesion pads
with bright steel. Steel cord style is not a limitation to the
present invention and, therefore, other styles of steel cord are
applicable.
[0027] A preferred embodiment for practicing the present invention
is in a tire design that employs steel reinforcement cords that are
plated or unplated and which have been cut to fixed lengths. Where
the steel reinforcement cords are unplated, i.e., bright steel, the
vulcanized rubber composition containing silane compounds adheres
to the entire surface area of the reinforcement cord. Where the
steel reinforcement cords comprise plated steel, bright steel
surfaces may be found at each of the cord ends at the cross section
where the cords were cut. And vulcanized rubber compositions
containing silane compounds will adhere to these bright steel
surfaces.
[0028] A nonlimiting exemplary method for preparing the
vulcanizable rubber compositions was performed. A typical skim
formulation used for belt reinforcement of tires was mixed on an
1.1L Banbury mixer. Mix times were about seven minutes with a final
Banbury temperature of 325.degree. F. (163.degree. C.). The stocks
mixed in this manner were final milled at a temperature below
220.degree. F. (104.degree. C.). At this time, the silane adhesion
promoters were added to the skim stock. Formulations are provided
in Tables III and IV.
3TABLE III Final Mill Mix-Masterbatches A and B 1 2 3 4 5 6 7 8
Masterbatch A 163 163 163 163 0 0 0 0 Masterbatch B 0 0 0 0 161 161
161 161 Sulfur (80%) 3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 in Oil Pre-
0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 vulcanization Inhibitor 0.9 0.9 0.9
0.9 0.9 0.9 0.9 0.9 Accelerator HMTA/SA.sup.a 2.2 2.2 2.2 2.2 0 0 0
0 Resotropin.sup.b 0 0 0 0 2.2 2.2 2.2 2.2 Aminosilane 0.5 2.0 0 0
0.5 2.0 0 0 Mercaptosilane 0 0 0.5 2.0 0 0 0.5 2.0 TOTAL 170.4
171.9 170.4 171.9 168.4 169.9 168.4 169.9 .sup.a)hexamethylene
tetraamine/stearic acid (95/5) .sup.b)resorcinol hexamethylene
tetraamine
[0029]
4TABLE IV Final Mill Mix-Masterbatches C and D 9 10 11 12 13 14 15
16 Masterbatch C 171 171 171 171 -- -- -- -- Masterbatch D -- -- --
-- 167 167 167 167 Sulfur (80%) in Oil 7.5 7.5 7.5 7.5 6.0 6.0 6.0
6.0 Pre-vulcanization 0.4 0.4 0.4 0.4 -- -- -- -- Inhibitor
Accelerator 0.6 0.6 0.6 0.6 -- -- -- -- Antioxidant 1.0 1.0 1.0 1.0
-- -- -- -- RFR.sup.a -- -- -- -- 4.0 4.0 4.0 4.0 TBBS.sup.b -- --
-- -- 0.35 0.35 0.35 0.35 Aminosilane 0.5 2.0 0 0 0.5 2.0 0 0
Mercaptosilane 0 0 0.5 2.0 0 0 0.5 2.0 TOTAL 181.0 182.5 181.0
182.5 177.85 179.35 177.85 179.35 .sup.a)resorsinol formaldehyde
resin .sup.b)t-butyl benzothiozole sulfeneaminde
[0030] The tests utilized T-adhesion pads prepared by placing 60
gauge (1.5 mm) slabs of uncured fully compounded rubber skim stock
on 51 gauge (1.3 mm) fabric reinforced rubber backing. Commercial
bright steel wire was placed between two pads of the reinforced
rubber skim stock with the wires in contact with the uncured rubber
skim at 1.25 cm intervals. The width of each adhesion pad was 1.25
cm. The pads were placed in a preheated curing mold and were cured
for 30 minutes at 149.degree. C. Rubber-steel cord adhesion testing
was done on a Model 1130 Instron Universal Tester at a crosshead
speed of 25.4 cm per minute and 110.degree. C. The T-adhesion pads
were preheated in the 110.degree. C. oven for 20 minutes prior to
testing. The test procedure was as follows.
DETAILED T-ADHESION TEST PROCEDURE
[0031] 1. Using a Clicker machine and a 15.24.times.1.25 cm die,
prepare an adequate number of calendared and control stock samples
for T-adhesion pad building.
[0032] 2. Use one piece of calendared fabric reinforced rubber
backing (0.1295 cm).
[0033] 3. Ply one piece of 60 gauge (1.5 mm) control rubber skim
stock onto the fabric backing.
[0034] 4. Place sample in building jig with fabric side down.
[0035] 5. Place ten cords (of brass or zinc coated wire).
[0036] 6. Invert another 2 ply assembly, made as in items 1, 2 and
3, on top of cords so that cords are between the 2 layers of rubber
skim stock to be tested.
[0037] 7. This assembly should now fit snugly into the cavity of
the curing mold.
[0038] 8. Adhesion pads shall be cured for 30 minutes at
149.degree. C. and then allowed to equilibrate for 24 hours before
testing.
[0039] 9. Testing Machine: Model 1130 Instron Universal Tester.
[0040] 10. Test speed 25.4 cm/minute; testing temperature,
110.degree. C. after 20 minutes preheat.
[0041] 11. The top grip shall be of a special holder made for the
cured sample, with a slot in the bottom to permit the sample to be
inserted with the wires protruding. The bottom grip should be a
wedge type, designed to exert increasing tightening as each wire is
pulled from the cured sample.
[0042] 12. Record 10 wire pull-outs and average. Multiply average
pull-out force value by 0.3572 to obtain kilograms per
centimeter.
[0043] All testing of the skim stocks was done in T-adhesion pad
prepared by placing 60 gauge (1.5 mm) slabs of uncured skin stock
on 50 gauge (1.3 mm) fiber reinforced backing. Sample width was one
half inch (1.25 cm). Clear wires were placed between two pads of
the reinforced skim stocks with the wires in contact with the
uncured skim and spaced at one half inch (1.25 cm) intervals. The
pads were placed in a mold and cured for 30 minutes at 300.degree.
F. (149.degree. C.). The pad where then steam bomb aged for one
hour at 300.degree. F. (149.degree. C.). The testing of these pads
was done on an Instron Universal tester at ten inches (25.4 cm) per
minute at 230.degree. F. (110.degree. C.).
[0044] Several tests were conducted on each of the 16 stocks for
comparison. Table V and VI show the results of the testing under
normal (unaged) conditions in a steam bomb at 90 percent relative
humidity at 95.degree. F. (30.degree. C.) for 60 to 180 days and in
a humidity chamber for 7 days. Humidity chamber aging is
significant for determining the chemical stability of chemical
bonds formed between the rubber stock and the metallic
reinforcement when exposed to conditions of high relative humidity
and high temperature, as compared to ambient, and extended periods
of time. The force necessary to pull or remove the metallic
reinforcement from the vulcanized rubber skim stock is given first,
in kilograms/cm, followed by the percent of rubber skim stock
remaining on the surface of the metallic reinforcement. The amount
of rubber skim stock remaining on the metallic reinforcement was
determined by visual examination and has been reported as % rubber
coverage.
5TABLE V Physical Properties Example Nos. 1 2 3 4 5 6 7 8 Monsanto
Rheometer 300.degree. F. (149.degree. C.) TS(2).sup.a (minutes) 5.4
2.7 3.2 1.6 5.1 2.7 3.9 1.9 TC(90).sup.b (minutes) 17.4 15.0 15.1
13.8 16.2 15.5 15.3 15.2 IP(L).sup.c 9.5 12.9 8.8 10.1 8.8 12.3 8.9
10.1 IP(90).sup.d 46.3 47.3 44.4 45.1 45.7 47.4 46.0 47.0
IP(100).sup.e 50.4 51.3 48.4 49.0 49.8 51.3 50.1 51.1 CRI.sup.f 8.3
8.1 8.4 8.2 9.0 7.8 8.8 7.5 Ring Tensile - 23' Cure 300% Mod (MPa)
22.43 -- 21.25 21.39 20.42 -- 19.46 19.80 Tensile Strength (MPa)
22.56 19.94 21.25 21.39 20.42 18.29 20.01 20.84 Elongation (%) 310
270 300 300 300 260 310 320 T-Adhesion to steel cord 12.5(0)
12.9(0) 14.3(0) 16.8(0) 11.1(0) 8.9(0) 14.3(10) 15.0(10)
(Unconditioned)(Kg/cm) T-Adhesion to steel cord 21.4(10) 21.1(10)
21.1(10) 24.6(20) 15.7(0) 14.6(0) 15.4(0) 18.9(10) (Steam
Bomb)(Kg/cm) T-Adhesion steel cord 5.0(0) 5.7(0) 4.3(0) 6.4(0)
4.6(0) 5.0(0) 5.0(0) 9.6(0) (Unconditioned)(Kg/cm) T-Adhesion steel
cord 13.6(0) 12.9(0) 9.3(0) 14.3(0) 8.6(0) 8.2(0) 8.9(0) 10.7(0)
(Steam Bomb)(Kg/cm) Humidity Chamber - Green Adhesion (Weight 15
lbs) (6.8 kg) 7 days 50.3(90) 42.5(90) Humidity Chamber - Green
Adhesion (Weight 15 lbs) (6.8 kg) 14 days 20.4 43.2 .sup.a)time to
scorch .sup.b)time to cure 90% .sup.c)minimum torque .sup.d)90% of
maximum torque .sup.e)maximum torque .sup.f)cure rate index
[0045]
6TABLE VI Physical Properties Example Nos. 9 10 11 12 13 14 15 16
Monosanto Rheometer 300.degree. F. (149.degree. C.) TS(2).sup.a 5.7
2.7 4.7 2.0 6.7 4.7 3.6 3.2 TC(90).sup.b 17.3 18.8 15.0 15.3 18.0
13.0 12.0 11.8 IP(2).sup.c 7.3 8.3 7.9 9.8 7.0 8.8 7.9 9.7
IP(90).sup.d 42.2 47.7 37.5 38.6 37.5 42.1 40.4 40.2 IP(100).sup.e
46.1 52.1 40.8 41.8 40.9 45.8 44.0 43.6 CRI.sup.f 8.6 6.2 9.7 7.5
3.7 4.2 3.8 3.6 Ring Tensile - 23' Cure 300% Mod (MPa) 15.23 18.98
13.11 13.52 12.21 14.15 12.01 12.63 Tensile Strength (MPa) 18.70
19.46 16.84 17.46 16.49 17.73 16.15 18.63 Elongation (%) 350 330
370 360 380 370 370 400 T-Adhesion to steel cord 13.9(0) 6.4(0)
16.8(10) 6.4(0) 27.5(60) 21.2(20) 32.9(80) 29.3(69) (Unconditioned)
(Kg/cm) T-Adhesion to steel cord 11.8(0) 8.9(0) 16.8(0) 8.6(0)
24.6(30) 23.2(20) 27.5(50) 35.0(70) (Steam Bomb) (Kg/cm) T-Adhesion
to steel cord 2.9(0) 2.9(0) 3.9(0) 3.2(0) 6.4(0) 4.6(0) 8.9(0)
5.0(0) (Unconditioned) (Kg/cm) T-Adhesion to steel cord 4.2(0)
2.9(0) 3.9(0) 2.1(0) 7.9(0) 6.4(0) 8.9(0) 9.6(0) (Steam Bomb)
(Kg/cm) Humidity Chamber - Green Adhesion (Weight 15 lbs) (6.8 kg)
7 Days 32.5(80) 45.4(80) 42.1(80) 31.1(90) 58.9(100) 49.7(90)
26.8(80) 55.0(100) .sup.a)time to scorch .sup.b)time to cure 90%
.sup.c)minimum torque .sup.d)90% of maximum torque .sup.e)maximum
torque .sup.f)cure rate index
[0046] Typical properties for a reinforcing belt skin would include
Shore A values of over 55, 300 percent modulus values of at least
6.9 MPa and elongations at break of at least 250 percent. With
reference to the physical properties reported in Tables V and VI,
all of the Examples showed 300 percent modulus and elongation
exceeding these values. T-adhesion values between rubber and bright
steel (unaged) were acceptable inasmuch as any adhesion is an
improvement over conventional stocks without the adhesion promoting
additives of the present invention, where little to no adhesion is
obtained. Steam bomb values were good and humidity chamber aging
values were very good.
[0047] In light of the foregoing, it should thus be evident that
the addition of certain silane compounds into vulcanizable rubber
compounds promotes adhesion between the rubber compounds and bright
steel. The known uses of such rubber compounds include belt skins
for belted tires, repair stocks for retreading of steel belts where
bright steel wire is exposed, and to enclose the bare steel ends of
cut wire belts. Other uses are evident in any application where
rubber would be bonded to unplated bright steel surfaces. This
could include golf club grips, motor mounts, cutless bearings,
torsilastic springs, power belts, printing rolls, metal wire
reinforced or braided hose, electrical deicers, shoe heels and
wherever it is desired to secure rubber to metal or provide a
flexible and strong, thermally stable bond between the same.
[0048] In conclusion, it is to be understood that all methods and
rubber compounds disclosed herein fall within the scope of the
claimed invention and that the subject invention is not to be
limited by the examples set forth herein. As will be apparent to
those skilled in the art, the formulations of the rubber
composition can be varied within the scope of the total
specification disclosure by selection of various amounts of the
silane compounds of the present invention and by substitution of
various components for any of the other, non-inventive components
of the rubber composition as well as the amounts thereof. While, in
accordance with the patent statutes, only the preferred embodiments
of the scope of the present invention have been described in detail
hereinabove, the present invention is not to be limited thereby.
Rather, the scope of the invention shall include all modifications
and variations that fall within the scope of the attached
claims.
* * * * *