FIELD OF INVENTION
[001] The subject matter described herein in general relates to the field of non-cobalt based adhesion promoters and more particularly relates to a rubber composition and their application to improve the adhesion of the rubber composition with reinforcement agents such as steel cords and wires.
BACKGROUND OF INVENTION
[002] In the manufacture of reinforced rubber products, such as tires and hoses, various reinforcing materials have been used to enhance the strength of the rubber articles. These reinforcing materials, in general, are made of rayon, nylon, polyester, steel wire and glass fibers. The steel wire used in these applications is primarily coated with brass, bronze or zinc. A primary requirement for effective reinforcement is that these reinforcing materials should be tightly bonded to the rubber. Maximum reinforcement of the rubber or rubber compound is achieved when a maximum adhesion is produced between the rubber and reinforcing element.
[003] Good adhesion is difficult to achieve where, for example in automobile tires, the article is subject to continuous flexing and exposure to high temperature during use. High initial adhesion could be obtained by providing good mechanical contact between the rubber and wire during the cure, but, upon aging and during the use of articles, the adhesive bond is often weakened or lost completely, which could result in premature failure of these articles. In order to prevent this, adhesion promoters are often used in the formulations, which can maintain a high level of adhesion between the rubber or rubber compounds and metal reinforcements during their service life. Quite a lot of research has been devoted towards developing materials that improve adhesion of elastomeric compounds to the metal cords and wires. CN101311237A discloses a fluorine rubber adhesion promoter comprising hexamethylene tetraamine, and resorcinol. US4436853A discloses a metal to rubber adhesion promoter comprising a reaction product of a phenol and a substituted melamine, wherein the primary reaction

product includes substituted benzoxazines. RU95108032A discloses a promoter of adhesion of rubber to steel cord based on cobalt resins of polymerized rosin obtained by reacting polymerized gum or tall rosin with cobalt oxide in the presence of acetic anhydride.
[004] Further, of the various methods employed to improve the adhesion of elastomeric compounds to the reinforcement elements, such as steel cords and wires, the commonly employed adhesion promoters include cobalt containing compounds, such as cobalt neodecanoate, cobalt boro-acylate, cobalt stearate, cobalt naphthenate, cobalt abietate and the similar ones. In order to obtain desirable properties in a wire breaker, carcass ply, or bead composition, the cobalt adhesion promoter is generally present in an amount of at least 0.05 to 0.25 phr of active cobalt per 100 phr by weight of elastomer. Although the use of cobalt adhesion promoters provides desirable results, there are drawbacks associated with its use, specifically, in terms of that the cobalt metal is rare metal and, therefore, the supply to rubber compounding applications, particularly on the radial tire productions could be unstable and relatively expensive. Moreover, the cobalt salts of organic acids are considered to be possible carcinogenic material to humans according to list of carcinogenic risks classified by the International Agency for Research on Cancer IARC Monographs on the Evaluation of Carcinogenic Risks to Humans (World Health Organization International Agency for Research on cancer Lyon, France 2006 Volume 86 Cobalt in Hard Metals and Cobalt Sulfate, Gallium Arsenide, Indium Phosphide and Vanadium Pentoxide). Some attempts were made on the use of other metal salts of organic aids in rubber compounds, in the place of cobalt salt, for improving steel cords adhesion. But the adhesive force just after the vulcanization was observed to be poor. Further, due to the poor adhesion of the reinforcement agent with other non-cobalt salts, attempts to replace cobalt salts were not successful in the past.
[005] In order to improve the performance of tires for longer service life, industries are always looking for non-cobalt adhesion promoter materials capable of providing

higher steel cords adhesion properties, lower costs with good supply ability, non-hazardous to humans and environments. Due to these facts, there is always a demand for non-cobalt based adhesion promoters for improving the adhesion of steel cords to the rubber compounds.
[006] Thus, the primary objective of the present disclosure is to provide non-cobalt adhesion promoter materials capable of providing the cure, mechanical and steel adhesion properties to rubber compositions that are comparable to cobalt based adhesion promoters.
SUMMARY OF THE INVENTION
[007] In a first aspect of the present disclosure, there is provided a vulcanizable rubber composition comprising: a. a rubber component; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I):

wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.
[008] In a second aspect of the present disclosure, there is provided a cured rubber composition obtained by vulcanization of the vulcanizable rubber composition

comprising: a. a rubber component; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I):

wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.
[009] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter
DETAILED DECRIPTION OF THE INVENTION
[0010] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.

Definitions
[0011] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.
[0012] The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
[0013] In the following description, all numbers disclosed herein are approximate values, regardless whether the word “about” or “approximate” is used in connection therewith. They may vary by 1 percent, 2 percent, 5 percent, or, sometimes, 10 to 20 percent. The terms “comprises,” “includes” and variations of these words do not have a limiting meaning where these terms appear in the description and claims. Thus, for example, a process that comprises “an” alkyl group can be interpreted to mean a process that includes “one or more” alkyl groups. In addition, the term “comprising,” which is synonymous with “including” or “containing,” is inclusive, open-ended, and does not exclude additional un-recited elements or process steps.
[0014] Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps.
[0015] The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably.
[0016] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely

for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a molar ratio range of about 6:1 to 1:6 should be interpreted to include not only the explicitly recited limits of about 0.1667 mole to about 6 mole, but also to include sub-ranges, such as 1 mole to 5 mole, 2 mole to 4 mole, and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 1.15 mole, 2.45 mole, and others.
[0017] The term “at least one” is used to mean one or more and thus includes individual components as well as mixtures/combinations.
[0018] The term “rpm” used herein refers to rotations/revolutions per minute, is a unit well used in the field of rubber technology to define the speed of any rotating part of the machine, in this disclosure especially a two-roll mill, Banbury mixer, an extruder machine and an underwater pelletizer.
[0019] The term “phr” used herein refers to parts per hundred rubber, it is a unit well defined in the field of rubber technology to define the amount of ingredients used.
[0020] The term “ML (1+4) @ 100oC” (or Mooney Viscosity at 100oC) used herein refers to conditions maintained while performing viscosity analysis on a sample of rubber or any other compound. It indicates the effect of temperature and time on the viscosity of rubber compounds. It is measured in terms of torque, required to rotate the disk embedded in the rubber/compound under specified conditions. Normally a pre¬heat period is given to the elastomer following which the disc starts to rotate. The highest viscosity is recorded initially which later starts to decrease with time and reaches its lowest value. Viscosity measured with a large rotor is twice of that measured with a small rotor. Viscosity is measured in Mooney Units (MU) denoted herein by M. With reference to present disclosure, L refers to Large rotor, 1 refers preheat time in

minutes, 4 refers to time in minutes after starting the rotor at which reading is taken, and 100oC refers to the test temperature.
[0021] The term “rheometer cure properties” used herein refers to rheological properties of rubber measured using a rheometer which is an instrument used to measure the viscoelastic properties of rubber during its curing process. A sample of rubber is placed inside the cavity of the rheometer and a positive pressure is applied to it at a constant temperature. As the sample gets heated under pressure, its viscosity and torque vary with time which is recorded as ML and MH values. ML (moment lowest) is recorded at room temperature when the sample has minimum viscosity and torque. As further curing occurs, the torque exerted on the rotor increases and attains its maximum value denoted by MH (moment highest). All the measurements in the rheometric curve are recorded in terms of dN*m with varying time. With reference to the present disclosure, t’-30 and t’-95 refers to the time at which 30% of MH torque value and 95% of MH torque value has been achieved.
[0022] The term “modulus-300%” used herein refers to the force required for 300% elongation of a material. It is measured in units of pressure as MPa or kg/cm2.
[0023] The term “tensile strength” used herein refers to the maximum load a material can withstand before fracture, breaking, tearing, etc. It is measured in the units of pressure as MPa or kg/cm2.
[0024] The term “elongation at break %” used herein refers to the percentage change in elongation of a material at the instant of break.
[0025] The term “tear strength (Die-C)” used herein refers to tear resistance of a soft vulcanized rubber when an angular test piece is employed. It is calculated by dividing the load in kg with the thickness of the test specimen in cm and expressed as kg/cm.
[0026] The term “hardness shore A” used herein refers to the resistance of a material to indentation. It is measured using a device called shore durometer. There are several

scales of a durometer out of which the two most common scales are A and D. Scale A is used for measuring the hardness of soft materials, such as polymers, elastomers and rubber.
[0027] The term “pull out force” used herein refers to the force(newtons) required to pull out the steel material from the rubber material. It indicates the force with which the materials are bind with each other. It is denoted in terms of load required in kilograms, times the time taken in seconds.
[0028] The term “natural rubber” used herein refers to elastic substance obtained naturally from the bark of trees. It majorly comprises of isoprene units and water along with some other impurities. The term “synthetic rubber” used herein refers to elastic substance obtained synthetically.
[0029] The term “adhesion promoter” used herein refers to substances that are used to encourage adhesion between two materials.
[0030] The term “adhesion” used herein refers to the joining of two different substances due to attraction forces that hold them together.
[0031] The term “antioxidant” used herein refers to substances that are used to protect the rubber articles against the attack of oxygen.
[0032] The term “antiozonant” used herein refers to substances that prevent the degradation of caused due to ozone cracking. Examples include ethylene di-urea, paraffin wax, and others.
[0033] The term “accelerator” used herein refers to compounding material used with a cross-linking agent to increase the speed of vulcanization of rubber and enhance its physical properties.
[0034] The term “rubber component” used herein refers to compounded rubber comprising one or more raw rubbers, such as natural rubber, synthetic rubber and

combinations thereof, additives such as carbon back, silica or any other conventional additive used in rubber industry, activator (s), rubber processing oil, antioxidant, antiozonant, vulcanizing agent including sulphur, insoluble sulphur and non-sulphur vulcanizing agent, accelerator(s).
[0035] The term vulcanizable rubber composition and composition are used interchangeably in the present disclosure.
[0036] In the structural formulae given herein and throughout the present disclosure, the following terms have been indicated meaning, unless specifically stated otherwise.
[0037] The term "alkyl" refers to a mono-radical, branched or unbranched, saturated hydrocarbon chain having from 2 to 18 carbon atoms. This term is exemplified by groups such as n-butyl, iso-butyl, t-butyl, n-hexyl, and the like. The groups may be optionally substituted.
[0038] The term "alkenyl" refers to a mono-radical of a branched or unbranched unsaturated hydrocarbon group preferably having from 2, 3, 4, 5, to 18 carbon atoms and having 1, 2, 3, inter alia double bonds. The groups may be optionally substituted.
[0039] The term "cycloalkyl" refers to carbocyclic groups of from 2 to 18 carbon atoms having a single cyclic ring or multiple condensed rings which may be partially unsaturated. Such cycloalkyl groups include, by way of example, single ring structures such as cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, and the like, or multiple ring structures or carbocyclic groups to which is fused an aryl group, for example indane, and the like. The groups may be optionally substituted.
[0040] The term "aryl" refers to any mono- and poly-carbocyclic ring systems wherein the individual carbocyclic rings in the polyring systems are fused or attached to each other via a single bond and wherein at least one ring is aromatic. Unless otherwise

indicated, substituents to the aryl ring systems can be attached to any ring atom, such that the attachment results in formation of a stable ring system.
[0041] `The term “arylalkyl” refers to the combined definition of the “alkyl” and “aryl” resulting in a stable ring system.
[0042] The term “neoacids” as used herein refers to a mixture of carboxylic acids with components of the mixture that are acids with the common property of a "trialkyl acetic acid" having three alkyl groups at carbon two for example, 2,2,3,5-Tetramethylhexanoic acid, and 2,4-Dimethyl-2-isopropylpentanoic acid, Neoacids with up to an average of about 20 carbon atoms are also available as mixtures of chain lengths and isomers, and are also suitable, as mixtures of any of the described neoacids in any proportions. Neodecanoic acid is readily available and forms low viscosity salts and is preferred. Neoacids with 7 or more carbon atoms are mixtures of isomers. For example, the typical isomer distribution of neodecanoic acid is: R1 and R2 are methyl, R3 is C6, 31%; R1 is methyl, R2 and R3 are C2 to C5, 67%; R1 is C2, R2 and R3 are C2 or C3, 2%.
[0043] The term “naphthenic acids” as used herein refers to naphthenic acids having the general structure: R4-(CH2)n-COOH, wherein R4 is a cyclic nucleus composed of one or more rings, i.e., cyclohexane, cyclopentane, and their alkylated cyclic nuclei in general; and n is an integer from 1 to about 14. The carboxylic acid group combines with the ring nucleus (R4) through methylene (CH2) groups. The simplest and typical acid, when n=1 is cyclopentane acetic acid. Naphthenic acids are a mixture of several cyclopentyl and cyclohexyl carboxylic acids and, a component of naphthenic acid can be represented by the following formula:


[0044] Commercial naphthenic acids suitable in this disclosure are mixtures of inseparable organic acids having from 7 to about 20 carbon atoms and a cyclic nucleus. Accordingly, the naphthenic acid is used as a mixture of substances having the formula given above and may also contain a minor amount of unsaponifiable material, which is unspecified but usually hydrocarbon in nature. Preferred naphthenic acids have equivalent weights per carboxylic acid functionality of less than about 300, and more preferred naphthenic acids less than about 250.
[0045] The term “mono and poly un-saturated fatty acids” as used herein refers to un-
saturated fatty acids obtained from the vegetable oil sources, such as linseed oil,
soybean oil, sunflower oil, rice bran oil and tall oil and could be available as a mixture
of oleic, linoleic and linolenic acids. The degree or extend of un-saturation present in
these un-saturated fatty acids can be determined by the iodine number determination
by Wijs method. The iodine value (or iodine adsorption value or iodine
number or iodine index) is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. Iodine numbers are often used to determine the amount of unsaturation in fatty acids. This unsaturation is in the form of double bonds, which reacts with iodine compounds. The higher the iodine number, the more C=C bonds are present in the fatty acid. Un-saturated fatty acids that could be suitable for the preparation of zinc salt complex of the present disclosure have iodine number values in the range of about from 80 to about 200. The determination of iodine value or number of fatty acids can be done using an ASTM – TM D5768 test method.
[0046] For the purpose of the present disclosure, non-limiting examples of suitable butadiene polymers include those polymers having rubber-like properties, prepared by polymerizing butadiene alone or with one or more other polymerizable ethylenically unsaturated compounds, such as styrene, methylstyrene, methyl isopropenyl ketone and acrylonitrile. The butadiene may be present in the mixture in an amount of at least 40% of the total polymerizable material. For the purpose of the present disclosure, the

reinforcement “fibres” can be selected from nylon, polyester, polyamide, aramid, and others.
[0047] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.
[0048] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally-equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.
[0049] As discussed in the background, the cobalt based adhesion promoters are rare metal and carcinogenic for human use. In view of this, the primary objective of the present disclosure is to provide an adhesion promoter that is lower in cost, less hazardous to human and environment and, also capable of improving the cure and mechanical properties of rubber compounds. The present disclosure discloses a vulcanizable rubber composition comprising a non-cobalt bonding promoter i.e., a zinc salt complex made from the combination of zinc oxide and carboxylic acids, particularly, in a specific molar ratio. The zinc salt complexes made according to the present disclosure provides improved adhesion, cure rate and mechanical properties in the cured and un-cured rubber compounds, similar to the well-known cobalt salt-based adhesion promoters.
[0050] The zinc salt complex useful for rubber compounding applications, according to the present disclosure, may be prepared by reacting zinc oxide with carboxylic acids in a particular molar proportion. The formation of zinc salt complex can be represented by the following reaction scheme:


[0051] However, the reaction is believed to proceed in two stages according to the following schemes:

[0052] With zinc oxide as the reactant, the formula of the basic Zn complex obtained may have (RCO2)6Zn4O or [(RCO2)2Zn]3ZnO (both structures being 100% basic compound of zinc carboxylate) structures. The structures of (RCO2)6Zn4O or [(RCO2)2Zn]3ZnO are believed to have zinc in a tetrahedral structure. In this zinc salt complex, the complex is having a tetrahedral structure with the four zinc atoms at the corners, the oxygen atoms in the center and the six carboxylate groups arranged along the sides, as shown in the following structure (Reference: Canadian Journal of Chemistry, Volume 61, page 1218 (1983):

[0053] Typically, the zinc metal carboxylate salt complex may be a basic metal carboxylate containing at least 50 wt %, or at least 60 wt % of the metal carboxylate. Previously known applications for these zinc salt complexes are in the areas of lubricating compositions, capable of improving the dispersant / detergent properties

and also reducing the acidity of lubricating oils (US patents: 3 367869; 3539513 and 9309478). A variety of elastomers and formulations employing various adhesion promoters are contemplated and disclosed with little or no success in providing long lasting wire adhesion under variety of externally abrasive conditions such as excessive heat and moisture. However, the wire adhesive vulcanizable rubber composition of the present disclosure exhibits improved adhesion properties, particularly after aging, as compared to conventional wire adhesion compositions employing cobalt adhesion promoters. The present disclosure is therefore further directed to a vulcanizable rubber composition having improvements in physical and mechanical properties such as dynamic stiffness, hardness, scorch safety, cure time and steel cords adhesion with the use of zinc salt complexes as an adhesion promoter.
[0054] In an embodiment of the present disclosure, there is provided a vulcanizable rubber composition comprising: a. a rubber component; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I):

wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.

[0055] In an embodiment of the present disclosure, there is provided the composition comprising: a. a rubber component including natural rubber, synthetic rubber, or combinations thereof; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I), wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.
[0056] In an embodiment of the present disclosure, there is provided the composition as
described herein, wherein the synthetic rubber selected from butadiene polymers such as
polybutadiene, isobutylene rubber (butyl rubber), ethylene-propylene rubber (EPDM),
neoprene (polychloroprene), polyisoprene, copolymers of 1,3-butadiene or isoprene
with monomers such as styrene, acrylonitrile and methyl methacrylate as well as
ethylene/propylene/diene monomer (EPDM) and in particular
ethylene/propylene/dicyclopentadiene terpolymers.
[0057] In an embodiment of the present disclosure, there is provided the composition comprising: a. a rubber component; b. at least one reinforcement component selected from cords, wires, fibers, fiberglass, mesh, or combinations thereof; and c. a basic zinc salt complex having structural Formula (I), wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.
[0058] In an embodiment of the present disclosure, there is provided the composition comprising: a. a rubber component; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I), wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt

complex promotes adhesion between the rubber component and the at least one reinforcement component, and wherein the at least one reinforcement component is steel in elongated form optionally coated with at least one metallic layer, particularly brass, zinc or bronze coated steel.
[0059] In an embodiment of the present disclosure, there is provided the composition comprising: a. a rubber component including natural rubber, synthetic rubber, or combinations thereof; b. at least one reinforcement component selected from cords, wires, fibers, fiberglass, mesh, or combinations thereof, wherein the steel is in elongated form optionally coated with at least one metallic layer, particularly brass, zinc or bronze coated steel ; and c. a basic zinc salt complex having structural Formula (I), wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.
[0060] In an embodiment of the present disclosure, there is provided, the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids.
[0061] In an embodiment of the present disclosure, there is provided, the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, wherein the carboxylic acid is selected from the group consisting of:
(i) Neoacids having the following structure:


wherein R1, R2, and R3 are each alkyl radicals containing 1 to about 16 carbon atoms, with the total number of carbon atoms contained in R1, R2, and R3 being from about 3 to about 18,
(ii) Naphthenic acids having the structure: R4-(CH2) n COOH
wherein R4 is a cyclic alkyl composed of one or more rings and n is an integer from 1 to about 14.
(iii) Linear chain aliphatic carboxylic acids having the structure: R5-COOH
wherein R5 is an alkyl chain containing about 1 to 18 carbon atoms.
(iv) Guerbet acids, obtained from Guerbet alcohols, of the structure:

wherein R6 is a hydrocarbyl group containing from about 2 to about 8 carbon atoms selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof, and R7 is a hydrocarbyl group containing from about 4 to about 10 carbon atoms, and R6 always contains exactly 2 carbon atoms less than R7; and
(v) Mono and poly un-saturated fatty acids.

[0062] In an embodiment of the present disclosure, there is provided the composition
as described herein, wherein the basic zinc salt complex is made from a reaction of zinc
oxide with carboxylic acids, and wherein the neoacids is selected from neopentanoic
acid, neoheptanoic acid, neooctanoic acid, neononanoic acid, neodecanoic acid,
neotridecanoic acid, 2,2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2-
isopropylpentanoic acid, 2,5-dimethyl-2-ethylhexanoic acid, 2,2-dimethyloctanoic acid or 2,2-diethylhexanoic acid.
[0063] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, and wherein the naphthenic acids is selected from the mixture of cyclopentyl and cyclohexyl carboxylic acids.
[0064] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, and wherein the linear chain aliphatic carboxylic acids is selected from acetic acid, propionic acid, butyric acid, lauric acid, palmitic acid or stearic acid.
[0065] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with guerbet carboxylic acids, and wherein the guerbet acids is selected from 2-ethylhexanoic acid, 2-butyloctanoic acid, 2-hexyldecanoic acid or 2-octyldodecanoic acid.
[0066] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with un-saturated carboxylic acids, and wherein the mono and poly un-saturated fatty acids is selected from oleic acid, linoleic acid, linolenic acid or tall oil fatty acid.

[0067] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, wherein the carboxylic acid is selected from the group consisting of:
(i) Neoacids having the following structure:

wherein R1, R2, and R3 are each alkyl radicals containing 1 to about 16 carbon atoms, with the total number of carbon atoms contained in R1, R2, and R3 being from about 3 to about 18, and wherein the neoacids is selected from neopentanoic acid, neoheptanoic acid, neooctanoic acid, neononanoic acid, neodecanoic acid, neotridecanoic acid, 2,2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2-isopropylpentanoic acid, 2,5-dimethyl-2-ethylhexanoic acid, 2,2-dimethyloctanoic acid or 2,2-diethylhexanoic acid.
(ii) Naphthenic acids having the structure: R4-(CH2) n COOH
wherein R4 is a cyclic alkyl composed of one or more rings and n is an integer from 1 to about 14, and wherein the naphthenic acids is selected from the mixture of cyclopentyl and cyclohexyl carboxylic acids.
(iii) Linear chain aliphatic carboxylic acids having the structure: R5-COOH
wherein R5 is an alkyl chain containing about 1 to 18 carbon atoms, and wherein the linear chain aliphatic carboxylic acids is selected from acetic acid, propionic acid, butyric acid, lauric acid, palmitic acid or stearic acid.

(iv) Guerbet acids, obtained from Guerbet alcohols, of the structure:

wherein R6 is a hydrocarbyl group containing from about 2 to about 8 carbon atoms selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof, and R7 is a hydrocarbyl group containing from about 4 to about 10 carbon atoms, and R6 always contains exactly 2 carbon atoms less than R7, and wherein the guerbet acids is selected from 2-ethylhexanoic acid, 2-butyloctanoic acid, 2-hexyldecanoic acid or 2-octyldodecanoic acid;
(v) and Mono and poly un-saturated fatty acids, and wherein the mono and poly
un-saturated fatty acids is selected from oleic acid, linoleic acid, linolenic acid or tall oil fatty acid.
[0068] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, and wherein the zinc oxide and the carboxylic acids is in a molar ratio ranging from 1:6 to 6:1. In another embodiment of the present disclosure, the zinc oxide and the carboxylic acids is in a molar ratio ranging from 1:5 to 2:1. In one another embodiment of the present disclosure, the zinc oxide and the carboxylic acids is in a molar ratio ranging from 1:4 to 1:1. In yet another embodiment of the present disclosure, the zinc oxide and the carboxylic acids is in a molar ratio ranging from 1:2 to 1:1.
[0069] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with the carboxylic acids, and wherein the zinc oxide and the carboxylic acids is in a molar ratio of 4:6.

[0070] In an embodiment of the present disclosure, there is provided a vulcanizable rubber composition comprising: a. a rubber component; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I):

wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component, and wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, wherein the carboxylic acid is selected from the group consisting of:
(i) Neoacids having the following structure:

wherein R1, R2, and R3 are each alkyl radicals containing 1 to about 16 carbon atoms, with the total number of carbon atoms contained in R1, R2, and R3 being from about 3 to about 18,

(ii) Naphthenic acids having the structure: R4-(CH2) n COOH
wherein R4 is a cyclic alkyl composed of one or more rings and n is an integer from 1 to about 14.
(iii) Linear chain aliphatic carboxylic acids having the structure: R5-COOH
wherein R5 is an alkyl chain containing about 1 to 18 carbon atoms.
(iv) Guerbet acids, obtained from Guerbet alcohols, of the structure:

wherein R6 is a hydrocarbyl group containing from about 2 to about 8 carbon atoms selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof, and R7 is a hydrocarbyl group containing from about 4 to about 10 carbon atoms, and R6 always contains exactly 2 carbon atoms less than R7; and
(v) Mono and poly un-saturated fatty acids.
[0071] In an embodiment of the present disclosure, there is provided the composition comprising: a. a rubber component; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I):


wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof; wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component; wherein the basic zinc salt complex is a free-flowing powder dispersed in silica.
[0072] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with the carboxylic acids, and wherein the basic zinc salt complex is a free-flowing powder dispersed in silica.
[0073] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with the carboxylic acids, and wherein the basic zinc salt complex is a free-flowing powder dispersed in silica, and wherein the zinc oxide and the carboxylic acids is in a molar ratio ranging from 1:6 to 6:1.
[0074] In an embodiment of the present disclosure, there is provided the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with the carboxylic acids, and wherein the basic zinc salt complex is a free-flowing powder dispersed in silica, and wherein the zinc oxide and the carboxylic acids is in a molar ratio of 4:6.

[0075] In an embodiment of the present disclosure, there is provided the composition as described herein, for use in the preparation of composite products selected from tires, power belts, conveyor belts, printing rolls, rubber shoe heels and soles, rubber wringers, automobile floor mats, mud flaps for trucks, and ball mill liners.
[0076] In an embodiment of the present disclosure, there is provided a cured rubber composition obtained by vulcanization of the composition as described herein.
[0077] In an embodiment of the present disclosure, there is provided a cured rubber composition obtained by vulcanization of the composition as described herein, for use in the preparation of composite products selected from tires, power belts, conveyor belts, printing rolls, rubber shoe heels and soles, rubber wringers, automobile floor mats, mud flaps for trucks, and ball mill liners.
[0078] In an embodiment of the present disclosure, there is provided a cured rubber composition obtained by vulcanization of the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, and wherein the zinc oxide and the carboxylic acids is in a molar ratio ranging from 1:6 to 6:1.
[0079] In an embodiment of the present disclosure, there is provided a cured rubber composition obtained by vulcanization of the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, and wherein the zinc oxide and the carboxylic acids is in a molar ratio of 4:6.
[0080] In an embodiment of the present disclosure, there is provided a cured rubber composition obtained by vulcanization of the composition as described herein, wherein the basic zinc salt complex is made from a reaction of zinc oxide with the carboxylic acids, and wherein the basic zinc salt complex is a free-flowing powder dispersed in silica, and wherein the zinc oxide and the carboxylic acids is in a molar ratio of 4:6.

[0081] In an embodiment of the present disclosure, there is provided a process of preparing the composition as described herein, the process comprising: (a) mixing at least one raw rubber selected from natural rubber, synthetic rubber and combinations thereof, at least one additive, at least one antiozonant, at least one antioxidant at a temperature in the range of 100-200oC for a time period in the range of 2 to 90 minutes to obtain a masterbatch; (b) adding a basic zinc salt complex or a control cobalt salt with the masterbatch at a temperature in the range of 100-150oC for a time period in the range of 2 to 90 minutes to obtain a green stock; (c) mixing vulcanization agent and at least one accelerator with the green stock at a temperature in the range of 50-100oC for a time period in the range of 1 to 30 minutes to obtain a final rubber composition, and; (d) conditioning of the final rubber composition at a temperature in the range of 22-35oC for a time period in the range of 6-26 hours to obtain the rubber composition.
[0082] In an embodiment of the present disclosure, there is provided a process of preparing the composition, the process as described herein, wherein at least one raw rubber is selected from natural rubber, synthetic rubber, or combinations thereof; at least one additive is selected from carbon black, zinc oxide, stearic acid, silica, fillers, plasticizers, waxes, processing oils, retarders or combinations thereof; at least one antiozonant is selected from 6PPD, micro-crystalline wax, or combinations thereof; at least one antioxidant is selected from Butylated Hydroxy Toluene (BHT), 2,2,4-Trimethyl-1,2-Dihydroquinoline polymer (TMQ), Thymoquinone (TQ), ZBEC, or combinations thereof; vulcanization agent is selected from sulfur, elemental sulfur, insoluble sulfur, or sulfur-donating groups; at least one accelerator is selected from amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithicarbonates, xanthates, or combinations thereof. Preferably, the primary accelerator is a sulfenamides
[0083] In an embodiment of the present disclosure, there is provided a process of preparing the composition, the process as described herein, wherein at least one raw rubber is a synthetic rubber selected from butadiene polymers such as polybutadiene,

isobutylene rubber (butyl rubber), ethylene-propylene rubber (EPDM), neoprene
(polychloroprene), polyisoprene, copolymers of 1,3-butadiene or isoprene with
monomers such as styrene, acrylonitrile and methyl methacrylate as well as
ethylene/propylene/diene monomer (EPDM) and in particular
ethylene/propylene/dicyclopentadiene terpolymers.
[0084] In an embodiment of the present disclosure, any conventional method of forming the wire breaker, carcass ply, bead component may be adapted for using the rubber component to prepare green tire or green article before vulcanizing.
[0085] In an embodiment of the present disclosure, there is provided a fabricated rubber article comprising vulcanizable rubber composition comprising: a. a rubber component; b. at least one reinforcement component; and c. a basic zinc salt complex having structural Formula (I); wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.
[0086] Although the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations are possible.
EXAMPLES
[0087] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices and materials are described herein. It is to be understood that this disclosure is

not limited to particular methods, and experimental conditions described, as such methods and conditions may apply.
[0088] The working and non-working examples as depicted in the forthcoming sections highlight the criticality of the working percentages of different components in achieving vulcanizable rubber composition of the present disclosure. It is further specified that the presence of all the components is critical so as to promote the desired adhesion between the rubber composition and the reinforcement component. The absence of any of components specified above or replacement of the same with any other component substantially affects adhesive properties of the vulcanizable rubber composition.
Materials and Methods
An organo-cobalt-boron salt complex commercially available under the trade name Manobond® 680C was procured from OM Group, Inc., Cleveland, Ohio. All the rubber compounding test results were provided by the TWC Rubber Application Center located at the R&D Center of Techno Waxchem Pvt. Ltd, in Kolkata, State of West Bengal, India. Cure properties were measured with an Alpha Technologies MDR / PREMIER RPA rheometer at 150o C, 0.5° arc and 1.67 Hz according to ASTM D-5289. The Mooney viscosity and Mooney scorch properties of rubber compositions were measured using an Alpha Technologies MV2000 Mooney viscometer according to ASTM D1646-04 method. The shore A hardness of unaged and heat aged rubber compound samples were measured according to ASTM-D2240-03. The tensile properties of unaged and heat aged rubber compound samples were measured according to ASTM D412. The Die - C Tear properties of rubber compound samples were measured according to ASTM D624C. The adhesion properties were measured according to ASTM D 2229-02 using a brass plated steel cord (wire: Hengxing Steel Wire, from China, 1x5x 0.3 HI with 63.5% copper plating). The samples were cured in the rheometer and tested under different ageing conditions according to ASTM D 2229-

02 method. For dynamic mechanical analysis (DMA), rubber process analyzer (MDR / PREMIER RPA) was used. In order to facilitate ease of handling, precipitated silica was used to disperse the liquid zinc salt complexes.
EXAMPLE 1
Synthesis of Zinc – 2-Ethyl hexanoate Salt Complex Using 2-Ethyl hexanoic Acid
[0089] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 21.6 grams (0.15 mole) of 2-ethyl hexanoic acid, 0.2 gram of butylated hydroxy toluene (BHT, antioxidant), 8.14 grams (0.1 mole) of zinc oxide and 150 ml of toluene (azeotrope solvent) were added and stirred well for proper mixing. The molar equivalents of the carboxylic acid: zinc oxide was at about 6:4 ratio. The contents of the flask were slowly heated, and the mixture was allowed to reflux for 1 – 5 hours. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged and stored. The zinc – 2-ethyl hexanoate complex salt prepared according to this procedure appeared to be clear transparent viscous yellowish liquid. Analysis of this zinc salt complex showed an active zinc content of 21.7 weight percent by the titration method.
EXAMPLE 2
Synthesis of Zinc – 2-Ethyl hexanoate Salt Complex Using 2-Ethyl hexanoic Acid
[0090] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 108.2 grams (0.75 mole) of 2-ethyl hexanoic acid, 0.3 gram of butylated hydroxy toluene (BHT, antioxidant), 42.3 grams (0.52 mole) of zinc oxide and 200 ml of toluene were added and stirred well for proper mixing. The molar equivalents of the carboxylic acid: zinc oxide was at about 6:4 ratio. The contents of

the flask were slowly heated and the mixture was allowed to reflux for 60 – 300 minutes. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged and stored. The zinc – 2-ethyl hexanoate complex salt prepared according to this procedure appeared to be clear transparent viscous yellowish liquid. Analysis of this zinc salt complex showed an active zinc content of 21.9 weight percent by the titration method. This zinc salt complex was dispersed onto precipitated silica as a free-flowing powder.
EXAMPLE 3
Synthesis of Zinc – 2-Ethyl hexanoate Salt Complex Using 2-Ethyl hexanoic Acid
[0091] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 209.1 grams (1.45 mole) of 2-ethyl hexanoic acid, 0.5 gram of butylated hydroxy toluene (BHT, antioxidant), 3.0 grams (0.05 mole) of acetic acid, 81.4 grams (1.0 mole) of zinc oxide and 500 ml of toluene were added and stirred well for proper mixing. The molar equivalents of an organic acid: zinc oxide is at about 6:4 ratio. The contents of the flask were slowly heated and allowed to reflux for 60 – 300 minutes. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged and stored. The zinc – 2-ethyl hexanoate complex salt prepared according to this procedure appeared to be clear transparent viscous yellowish liquid. Analysis of this zinc salt complex showed an active zinc content of 22.7 weight percent by the titration method.

EXAMPLE 4
Synthesis of Zinc – Neodecanoic acid Complex Salt Using Mixture of Carboxylic
Acids
[0092] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 258.5 grams (1.5 mole) of neodecanoic acid (mixture of carboxylic acids), 1.5 grams (0.025 mole) of glacial acetic acid 0.2 gram of butylated hydroxy toluene (BHT, antioxidant), 81.4 grams (1 mole) of zinc oxide and 100 ml of toluene were added and stirred well for proper mixing. The molar equivalents of the carboxylic acid: zinc oxide was at about 6:4 ratio. The contents of the flask were slowly heated and the mixture was allowed to reflux for 60 – 300 minutes. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged and stored. The zinc – neodecanoate complex salt prepared according to this procedure appeared to be clear transparent viscous yellowish liquid. Analysis of this zinc salt complex showed an active zinc content of 17.2 weight percent by the titration method.
EXAMPLE 5
Synthesis of Zinc – Neodecanoic acid Complex Salt Using Mixture of Carboxylic
Acids
[0093] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 1292.3 grams (7.5 moles) of neodecanoic acid (mixture of carboxylic acids), 0.5 gram of butylated hydroxy toluene (BHT, antioxidant), 396.8 grams (4.875 moles) of zinc oxide and 500 ml of toluene were added and stirred well for proper mixing. The molar equivalents of the carboxylic acid: zinc oxide was at about 6:4 ratio. The contents of the flask were slowly heated and the mixture was

allowed to reflux for 60 – 300 minutes. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged and stored. The zinc – neodecanoate complex salt prepared according to this procedure appeared to be clear transparent viscous yellowish liquid. Analysis of this zinc salt complex showed an active zinc content of 19.6 weight percent by the titration method. This zinc salt complex was dispersed onto precipitated silica as a free-flowing powder.
EXAMPLE 6
Synthesis of Zinc – Neodecanoic and Oleic Acids Complex Salt Using Mixture of
Carboxylic Acids
[0094] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 43.9 grams (0.255 moles) of neodecanoic acid (mixture of carboxylic acids), 3 grams (0.05 mole) of glacial acetic acid, 17.4 grams (0.06 mole) of oleic acid, 0.2 gram of butylated hydroxy toluene (BHT, antioxidant), 20 grams (0.245 moles) of zinc oxide and 100 ml of toluene were added and stirred well for proper mixing. The molar equivalents of the carboxylic acid: zinc oxide was at about 6:4 ratio. The contents of the flask were slowly heated and the mixture was allowed to reflux for 60 - 300 minutes. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged

and stored. The zinc – neodecanoate complex salt prepared according to this procedure appeared to be clear transparent viscous yellowish liquid.
EXAMPLE 7
Synthesis of Zinc Salt of Un-saturated Fatty Acids Complex (Using Mixture of
Oleic and Linoleic Acids)
[0095] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 175.2 grams (0.652 mole) of oleic acid - linoleic acid mixture (mixture of unsaturated fatty acids, Iodine Value = about 129), 0.5 gram (0.008 mole) of glacial acetic acid and 32.6 grams (0.4 mole) of zinc oxide and 100 ml of toluene were added and stirred well for proper mixing. The molar equivalents of the carboxylic acid: zinc oxide was at about 6.5:4 ratio. The contents of the flask were slowly heated and the mixture was allowed to reflux for 60 – 300 minutes. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged and stored. The zinc-unsaturated fatty acids complex salt prepared according to this procedure appeared to be a beige color solid very soft in nature. Analysis of this zinc salt complex showed an active zinc content of 12.61 weight percent by the titration method.
EXAMPLE 8
Synthesis of Zinc Salt of Un-saturated Fatty Acids Complex (Using Mixture of
Oleic and Linoleic Acids)
[0096] Into a round bottomed flask equipped with a mechanical stirrer, thermometer and a Dean-Stark condenser, 1226.4 grams (4.56 moles) of oleic acid - linoleic acid mixture (mixture of unsaturated fatty acids, Iodine Value = about 129), 228.2 grams

(2.8 moles) of zinc oxide and 500 ml of toluene were added and stirred well for proper mixing. The molar equivalents of the carboxylic acid: zinc oxide was at about 6.5:4 ratio. The contents of the flask were slowly heated and the mixture was allowed to reflux for 60 - 300 minutes. After this, heating and stirring were maintained until all of the water from the reaction had been collected in the Dean-Stark. Even after collecting the water, the reaction was continued under the reflux conditions for additional 3 to 5 hours. Now, the reaction mixture was filtered to remove any solids or un-reacted material. Finally, the solvent toluene was first removed under atmospheric conditions and then at 150 – 160 oC / 15 – 20 “Hg vacuum conditions. The product was discharged and stored. The zinc – unsaturated fatty acids complex salt prepared according to this procedure appeared to be a beige color solid very soft in nature. Analysis of this zinc salt complex showed an active zinc content of 13.5 weight percent by the titration method. This zinc salt complex was dispersed onto precipitated silica as a free-flowing powder.
EXAMPLE 9
Vulcanizable rubber composition compounding:
[0097] The rubber composition of basic zinc salt complex was prepared according to the process of the present disclosure, using different carboxylic acids, as shown in examples above. They were further evaluated as adhesion promoters in a black natural rubber composition to assess their performance in improving the steel-wire adhesion properties. For a comparison, in a control composition, a commercially available organo-cobalt-boron salt complex was used. To determine the effectiveness of basic zinc salt complex as an adhesion promoter, the effective amount of zinc metal present in the zinc salt complex was maintained. The details are presented in Table 1 along with various other components present in the rubber compositions.
TABLE1: RUBBER COMPOUND FORMULTION


EXAMPLE 10
Process of preparation of rubber composition
[0098] Four rubber compositions, each comprising a different bonding promoter complex, in the same general formulation as shown in Table 1, were prepared in a three-stage mixing procedure. In the first stage mixing, all the ingredients were mixed to about 150° C temperature in a Banbury mixer for 2 to 20 minutes to produce a masterbatch. In the second stage mixing, different basic zinc salt complexes prepared according Example 2, 5 and 8 and a control cobalt salt composition were added to the masterbatch on a two-roll mill at about 90 - 121° C for 2 to 20 minutes to produce a green stock. In the third stage mixing, insoluble sulfur and an accelerator were mixed for 2 to 20 minutes with the green stock obtained from the second stage mixing at about 95° C to prepare the final rubber compositions. These rubber compositions were conditioned overnight at a constant temperature room at about 23° C and at 50%

relative humidity. The obtained vulcanizable rubber compositions were then tested for rheometer cure, shaped and optimum cured at 150° C for the evaluation of the wire adhesion, physical, mechanical and dynamic mechanical properties.
EXAMPLE 11
Testing for cure properties
[0099] Rheometer cure properties of the green stock obtained after second stage of mixing were measured and compared against that of control cobalt salt composition as recorded in Table 2


[00100] Table 2 indicates a marked decrease in the moment lowest (ML) and
moment highest (MH) torque values of the rubber compositions of the present disclosure, thus suggesting a decrease in the stiffness, thereby obtaining a desired flexibility of both the uncured and cured rubber compositions respectively. Moreover, it was noted that the rubber compositions showed a sharper increase in torque in going from T10 to T90 as compared to the control cobalt salt composition, indicating an increased cure rate which is a desirable aspect for an uncured rubber composition. The observed cure rate provides the rubber composition of the present disclosure with advantageous in terms of ease of handling and processability.
EXAMPLE 11
Testing for Mooney viscosity and scorch properties:
[00101] The green stock was characterized as to Mooney viscosity and scorch
properties. Reduction in compound Mooney viscosity is advantageous because it provides better processability and handling, especially during the extrusion process. In contrast, a high compound Mooney viscosity can cause subsequent tire build problems, for example, difficulties in filling the tire mold during the cure step and can result in modulated inner belts in the tires. The Mooney viscosity at 100oC and Mooney Scorch

at 127oC properties of rubber compositions. The comparable results obtained on the rubber compositions are shown in Table 3.

[00102] It is evident from data revealed in Table 3, that the Mooney viscosities
of rubber compositions comprising basic zinc salt complex showed improved properties i.e., overall reduction in Mooney viscosity and scorch time as compared to the control cobalt salt composition. These combined results obtained for rheometer cure properties and the Mooney viscosity, render the vulcanizable rubber composition of the present disclosure suitable for wire adhesion applications.
EXAMPLE 12
Testing for tensile properties
[00103] The aged and unaged rubber compositions were investigated for tensile
properties such as applied modulus at 100%, 200% and 300% elongation, % elongation at break, tensile strength, hardness shore A and tear strength. The obtained results were compared with that of control cobalt salt composition. Table 4 reveals the data recorded.


[00104] It can be inferred from the data shown in Table 4 that the unaged and
aged tensile modulus (100, 200 and 300 %) properties of the rubber compositions comprising the basic zinc salt complex of the present disclosure showed improved results over the control cobalt salt composition. Overall, comparable or improved results for tensile strength, elongation at break, hardness shore A and tear strength were observed for the rubber composition of the present disclosure.
EXAMPLE 13
Testing for steel cord adhesion properties
[00105] The adhesive properties of rubber compositions were measured using a
brass plated steel cord (embedded 12.5 mm into the rubber pad. The samples were cured in the rheometer at 150° C for 40 minutes and then tested under unaged condition, heat aged, hot water aged and salt water aged conditions. The steel cords adhesion values are shown in Table 5.


[00106] The data illustrated in Table 5 clearly indicates that the rubber
compositions comprising basic zinc salt complex of the present disclosure exhibits improved steel cord adhesion properties as compared to the control cobalt salt composition under a variety of ageing conditions. In the rubber compositions of the present disclosure, a significant improvement in rubber coverage after heat and hot water ageing was observed. Under hot water ageing conditions, the adhesive force of zinc salt complex showed much higher values compared to the conventional cobalt salt composition. Replacement of the cobalt salt adhesion promoter with the basic zinc salt complex of the present disclosure generally has beneficial effects on the pull-out force and rubber coverage after heat aging. The rubber compositions of the present disclosure without cobalt salt adhesion promoter preferably showed good retention of rubber coverage. However, the wire adhesion composition of the present disclosure without the cobalt adhesion promoter also shows significantly higher pull-out force and coverage in comparison to the conventional control cobalt salt adhesion promoter loaded wire adhesion compositions. Overall, it can be concluded that the basic zinc salt complex provides greater steel cord adhesive forces and enhanced resistance under

different external abrasive conditions to the rubber composition of the present
disclosure.
[00107] These results clearly suggest that a non-cobalt adhesion promoter
system, if properly developed, could potentially replace cobalt based adhesion
promoters that are currently used in the manufacture of radial tires.
EXAMPLE 14
Dynamic mechanical analysis (DMA)
[00108] Dynamic mechanical properties of cured steel skim rubber
compositions were determined. The PREMIER RPA is capable of testing uncured or cured rubbers with a high degree of repeatability and reproducibility. The tests and subtests available include strain sweep at constant frequency and temperature, frequency sweeps at constant temperature, and temperature sweeps at constant strain and frequency. The accuracy and precision of the instrument allows reproducible detection of changes in the compounded sample. Using the RPA instrument, dynamic mechanical analysis (DMA) data was obtained at 60 oC, under the strain sweep conditions at constant frequency. For tan delta (δ) properties of rubber compositions of the present disclosure and the data is presented in Table 6.


The data shown in Table 6 clearly demonstrates that the basic zinc salt complexes of the present disclosure showed less hysteresis properties in the cured rubber compound while maintaining adhesion properties comparable to control cobalt salt composition. Improving the tan delta (δ) properties of steel skim rubber composition is important for maintaining or reducing adhesion property loss under the dynamic conditions of tires. The durability of tires during their service life could be enhanced if the steel skim rubber compounds exhibit low hysteresis (Tan Delta (δ)) properties.
[00109] The RPA instrument was also used in the analysis of tan delta (δ)
properties of cured rubber compositions under temperature sweep conditions at constant strain and frequency. The data obtained are presented in TABLE 7.


[00110] Again, the data revealed in Table 7 clearly demonstrates, that the basic
zinc salt complexes of the present disclosure exhibit improved DMA properties, such as low hysteresis properties in the cured rubber compositions as compared to the traditional cobalt salt-based adhesion promoter compositions.
[00111] As it is demonstrated in the above examples, the non-cobalt adhesion
promoter i.e. the basic zinc salt complex was capable of providing a performance equal to that of cobalt based adhesion promoters. The basic zinc salt complexes prepared by the reaction of zinc oxide with carboxylic acids, with specific molar ratios of zinc oxide to carboxylic acids, provide rubber composition properties similar to or improved than the control cobalt salt composition. However, the improved processability such as lower Mooney viscosity of the uncured rubber compositions does not compromise with other performance properties. On the other hand, the adhesion properties, tensile properties, tear properties, dynamic mechanical properties such as the hysteresis (Tan Delta - δ) of the cured rubber compositions of the present disclosure were found to be comparable or rather improved from the conventionally used cobalt-based adhesion promoter compositions. Due to these factors, the use of the non-cobalt salt-based

compositions, such as the basic zinc salt complex developed in the present disclosure in the rubber compounding applications yield more commercially successful rubber products.
[00112] While the disclosure has been described with respect to a limited
number of embodiments, the specific features of one embodiment should not be attributed to other embodiments of the disclosure. No single embodiment is representative of all aspects of the disclosure. In some embodiments, the compositions may include numerous compounds not mentioned herein. In other embodiments, the compositions do not include, or are substantially free of, any compounds not enumerated herein. Variations and modifications from the described embodiments exist. The method of making the composition is described as comprising a number of acts or steps. These steps or acts may be practiced in any sequence or order unless otherwise indicated. Finally, any number disclosed herein should be construed to mean approximate, regardless of whether the word “about” or “approximately” is used in describing the number. The appended claims intend to cover all those modifications and variations as falling within the scope of the disclosure.
Advantages of the present disclosure
[00113] The above-mentioned implementation examples as described on this
subject matter and its equivalent thereof have many advantages, including those which are described.
[00114] The non-cobalt adhesion promoters developed so far did not provide
good steel cords adhesion properties with rubber compositions, and therefore, had not been used in the manufacture of steel cords reinforced rubber products. Now, according to the present disclosure, the basic zinc salt complex developed on the basis of a specific molar ratio of zinc oxide and carboxylic acid derivatives, exhibited good steel cords adhesion, physical and mechanical properties in the un-cured and cured rubber compositions as compared to the traditional cobalt based adhesion promoters. Due to

the above factors, the vulcanizable rubber composition comprising the basic zinc salt complex of the present disclosure is highly advantageous as it is lower in cost, environmentally friendly and particularly useful in improving the adhesion of coated steel cords. Therefore, the non-cobalt bonding promoter rubber compositions developed in the present disclosure, could potentially be applied in the manufacture of radial tires, hoses and other industrial rubber composite products.
[00115] Although the subject matter has been described in considerable detail
with reference to certain embodiments thereof, other embodiments are possible. As such, the spirit and scope of the disclosure should not be limited to the description of the embodiments contained herein.

I/We Claim:
1. A vulcanizable rubber composition comprising:
a. a rubber component;
b. at least one reinforcement component; and
c. a basic zinc salt complex having structural Formula (I):

wherein R is a hydrocarbyl radical containing from 2 to 18 carbon atoms independently selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof;
wherein the basic zinc salt complex promotes adhesion between the rubber component and the at least one reinforcement component.
2. The composition as claimed in claim 1, wherein the rubber component includes natural rubber, synthetic rubber, or combinations thereof.
3. The composition as claimed in claim 1, wherein the at least one reinforcement component is selected from cords, wires, fibres, fiberglass, mesh, or combinations thereof.
4. The composition as claimed in claim 1, wherein the at least one reinforcement component is steel in elongated form optionally coated with at least one metallic layer, particularly brass, zinc or bronze coated steel.

5. The composition as claimed in claim 1, wherein the basic zinc salt complex is made from a reaction of zinc oxide with carboxylic acids, wherein the carboxylic acid is selected from the group consisting of:
(vi) Neoacids having the following structure:

wherein R1, R2, and R3 are each alkyl radicals containing 1 to about 16 carbon atoms, with the total number of carbon atoms contained in R1, R2, and R3 being from about 3 to about 18,
(vii) Naphthenic acids having the structure: R4-(CH2) n COOH
wherein R4 is a cyclic alkyl composed of one or more rings and n is an integer from 1 to about 14.
(viii) Linear chain aliphatic carboxylic acids having the structure: R5-COOH
wherein R5 is an alkyl chain containing about 1 to 18 carbon atoms.
(ix) Guerbet acids, obtained from Guerbet alcohols, of the structure:


wherein R6 is a hydrocarbyl group containing from about 2 to about 8 carbon atoms selected from alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or combinations thereof, and R7 is a hydrocarbyl group containing from about 4 to about 10 carbon atoms, and R6 always contains exactly 2 carbon atoms less than R7; and
(x) Mono and poly un-saturated fatty acids.
6. The composition as claimed in claim 5, wherein the neoacids is selected from neopentanoic acid, neoheptanoic acid, neooctanoic acid, neononanoic acid, neodecanoic acid, neotridecanoic acid, 2,2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2-isopropylpentanoic acid, 2,5-dimethyl-2-ethylhexanoic acid, 2,2-dimethyloctanoic acid or 2,2-diethylhexanoic acid.
7. The composition as claimed in claim 5, wherein the naphthenic acids is selected from the mixture of cyclopentyl and cyclohexyl carboxylic acids.
8. The composition as claimed in claim 5, wherein the linear chain aliphatic carboxylic acids is selected from acetic acid, propionic acid, butyric acid, lauric acid, palmitic acid or stearic acid.
9. The composition as claimed in claim 5, wherein the guerbet acids is selected from 2-ethylhexanoic acid, 2-butyloctanoic acid, 2-hexyldecanoic acid or 2-octyldodecanoic acid.
10. The composition as claimed in claim 5, wherein the mono and poly un-saturated fatty acids is selected from oleic acid, linoleic acid, linolenic acid or tall oil fatty acid.
11. The composition as claimed in claim 5, wherein the zinc oxide and the carboxylic acids is in a molar ratio ranging from 1:6 to 6:1.
12. The composition as claimed in claim 5, wherein the zinc oxide and the carboxylic acids is in a molar ratio of 4:6.

13. The composition as claimed in claim 1, wherein the basic zinc salt complex is a free-flowing powder dispersed in silica.
14. The composition as claimed in claim 1, for use in the preparation of composite products selected from tires, power belts, conveyor belts, printing rolls, rubber shoe heels and soles, rubber wringers, automobile floor mats, mud flaps for trucks, and ball mill liners.
15. A cured rubber composition obtained by vulcanization of the composition as claimed in claim 1.