Compositions – Compositions containing a single chemical reactant or plural... – Organic reactant
Reexamination Certificate
1994-02-03
2001-01-09
Henderson, Christopher (Department: 1713)
Compositions
Compositions containing a single chemical reactant or plural...
Organic reactant
C252S182130, C252S182260
Reexamination Certificate
active
06171517
ABSTRACT:
TECHNICAL FIELD
Our present invention is directed to a formulation for producing a cured elastomeric article. Such a formulation includes insoluble sulfur.
Our invention prevents the conversion of insoluble sulfur to soluble sulfur, soluble sulfur being able to migrate to the surface of the elastomeric article prior to vulcanization.
BACKGROUND ART
It is generally well-known that an atmosphere which contains oxygen can cause surface cracking of conventional unsaturated rubber vulcanizates when subjected to repeated flexing in an oxygen-containing environment. Deterioration has been observed to occur when small “surface” cracks grow rapidly into deep, disruptive fissures. Fissures of this sort can significantly shorten the serviceable life of an elastomeric article made from a rubber vulcanizate.
The ongoing desire to prolong the useful life of elastomeric articles made from rubber—either natural or synthetic—is also well known.
U.S. Pat. No. 4,158,000 to Nagasaki et al., for example, discloses antidegradants for rubber, said to be useful for preventing heat-aging and flex-cracking. A mixture consisting essentially of specified percentages of 2,2,4-trimethyl-1,2-dihydroquinoline monomer, dimer thereof and more-highly-polymerized products are mentioned in the Nagasaki patent as providing rubber with such an antidegradant ingredient.
U.S. Pat. No. 2,400,500 to Gibbs, moreover, discloses various condensation products of 1,2-dihydroquinolines with diarylamines, said to be useful in preventing flex-cracking of rubber. Gibbs mentions in this patent that reacting an alipathic ketone with a primary aromatic amine to produce a 1,2-dihydroquinoline is known.
2,2,4-trimethyl-1,2-dihydroquinoline, a principal product resulting from the reaction of acetone and aniline, is a known useful antioxidant.
Many chemical antidegradants, principally based upon amine chemistry, have in fact been developed to arrest or otherwise delay the physical deterioration of articles made from cured elastomeric materials.
Current formulations for producing cured elastomeric articles typically include an insoluble form of sulfur, which prevents sulfur migration prior to vulcanization. Conversion of the insoluble form of sulfur to its soluble form, which is currently known to result in migration of soluble sulfur to the surface of an uncured rubber article, appears to be caused by the presence of amine-based antidegradants.
While mixtures which include 2,2,4-trimethyl-1,2-dihydroquinoline are known to prolong the useful life of elastomeric articles, which is desirable, the presence of 2,2,4-trimethyl-1,2-dihydroquinoline and its various forms are known to cause insoluble sulfur to convert to a soluble form of sulfur, which is undesirable.
For example, soluble sulfur is known to migrate to the surface of uncured rubber articles. Migration of this sort, called sulfur “bloom,” is known to cause loss of “building tack.”
The term “building tack” refers to certain adherence properties of uncured elastomeric materials such as rubber, particularly when such materials are produced as relatively-thin sheets and such sheets are thereafter layered and utilized in the fabrication of a tire.
Obtaining undesirable “building-tack” properties, using these sorts of elastomeric materials, can thus become a matter of concern.
OBJECTS OF INVENTION
One object of our present invention, therefore, is to markedly reduce the rate at which an insoluble form of sulfur converts to its soluble form. A related object is to prevent sulfur “bloom.” Still another object is to prolong, for extended periods of time, many of the desirable physical properties of cured elastomeric articles. Additional features and advantages of our present invention will become apparent to those skilled in the art upon reading the following specification.
SUMMARY DISCLOSURE
One aspect of our invention is directed to a novel formulation for producing a cured elastomeric article.
Another aspect of our invention concern methods of producing our formulation. Our formulation includes a non-migratable form of sulfur, known as insoluble sulfur.
In reference to the preparation of our novel formulation, we have discovered that select relative amounts of (A) a first reactive ingredient and (B) a second reactive ingredient, when combined in a chemically-reactive environment, can be utilized to produce (C) a reaction product that is effective for reducing the rate at which insoluble sulfur converts to a migratable form of sulfur (soluble sulfur).
The first reactive ingredient (A) is itself a reaction product, resulting from the reactive combining of an aliphatic ketone with a primary aromatic amine. The second reactive ingredient (B) is an acid anhydride.
The two reactive ingredients (A and B) are reactively combined and thus converted to our novel product (C).
We have found that our product (C), because it results from utilizing an amine-based reactant, is able to provide our novel formulation with certain desirable physical properties, such as those otherwise typically provided by an amine-based antidegradant.
Industrial Applicability
Our present invention can be used to make various articles from unsaturated rubber vulcanizates. Such rubber may be natural, synthetic, or a mixture of both.
Some representative examples of unsaturated elastomers commonly used in the composite articles of our present invention include natural rubber, synthetic polyisoprene, polychloroprene, so-called “cyclene” rubbers, norbornene rubbers, polysulfide rubbers, styrene-butadiene rubbers, polybutadiene rubbers, nitrile rubbers, carboxylated nitrile rubbers, butyl rubbers, ethylene-propylene-diene monomer-based (“EPDM”) rubbers, epichlorohydrin homopolymers and copolymers, ethylene-propylene rubbers (“EPR”), and polyisobutylene rubbers.
We would currently expect the major commercial use in the near term to be in the areas of tires, conveyor belts, and elastomeric hoses.
In particular, the antidegradant composition of the present invention can be used most advantageously as any component or portion of a tire. Such uses include wire belt or carcass portions of a tire. Such a tire may be a truck tire, a passenger tire, or an off-the-road vehicle tire. Moreover, any such tire may contain many different reinforcing elastomeric layers therein, any such layer embodying different features of our invention. For example, tire components of these sorts typically contain more than one thermosetting rubber polymer in a blend which must be protected from oxidative attack.
Our data presented below demonstrates that the antidegradant compositions of our present invention prevent conversion of insoluble sulfur to its soluble forms. The antidegradant compositions of our present invention also improve oxygen-resistance and heat-aging properties of the elastomeric materials in which our novel compositions are incorporated. Yet, our novel compositions do not cause any noticeable reduction in flexural properties of the elastomeric materials in which they are incorporated.
Also, the novel antidegradant compositions of our present invention are typically solids, which promotes ease-of-use.
BEST MODE FOR CARRYING OUT INVENTION
Typically, the “A” ingredient (i.e., the reaction product of an aliphatic ketone and a primary aromatic amine) and the “B” ingredient (an acid anhydride) are combined in a chemically-reactive environment and are subsequently utilized to produce “C”, the novel antidegradant ingredient of our invention.
Also, typically 85 to 99 weight percent A, preferably 90 to 98 weight percent A, and most preferable 93 to 96 weight percent A, is combined with sufficient B such that the sum of the weight of the A and B ingredients accounts for 100 percent of the total weight of the novel antidegradant ingredient C that is incorporated into a formulation for producing a cured elastomeric article.
The term “elastomeric” is understood to include rubber-like polymers and co-polymers as well as various compositions which have been characterized as “rubber” by those skilled in the art, such as natural rubber, synthetic rubber
Cornell Robert Joseph
Roberts Darilyn Helen
True William Robert
Henderson Christopher
Reitenbach Daniel
Uniroyal Chemical Company, Inc.
LandOfFree
Rubber compounding formulation and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rubber compounding formulation and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rubber compounding formulation and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2484766