Title of Invention	"A NOVEL SYNERGISTIC ADHESIVE COMPOSITION"
Abstract	A novel synergistic adhesive composition useful for bonding vulcanizable elastomeric rubbers to a substrate, said composition comprising a styrenic block copolymer, natural rubber, tackifier resin sulfur, accelerator, zinc oxide, antioxidant and other conventional additives.

Full Text

Field of the Invention This invention relates to a novel adhesive composition used for coating of patches which are used for repair of rubber based substrates. The invention also provides a process for manufacture of the adhesive composition. Background and Prior Art of the Invention Damaged tyres and tubes are repaired by several methods. A very popular method is use of patches. Several patches are available in the market, such as chemical cure patches that contain a main body of vulcanized rubber and a thin layer of nonvulcanised rubber (cushion gum) adhered thereto. A vulcanizing fluid is applied to this patch. The fluid reacts with the uncombined sulphur to fully cure the rubber. Another chemical cure patch is one which involves the use of an amine curable polyurethane or other prepolymer and a treating agent. The treating agent is applied in several coats to the broken surface of the tyre and allowed to dry. Then the amine curable urethane is applied and then covered with a patch, which has also been previously treated with a treating agent. The patch is tapped into place and firmly held by inflating the curing tube inside the tyre. The curing occurs at ambient temperature after standing approximately 16-18 hours. This technology also is user sensitive, time consuming and moreover involves the use of a treating agent. Yet another popular method is the use of uncured patches wherein the uncured rubber such as cushion gum, is first added to the aperture or hole. Next, the patch area is buffed and uncured patch is then appropriately positioned and cured with heat. This repair route is not only long and tedious, but also requires the utilization of heat. The use of pressure sensitive adhesive (PSA) patches is a modern concept for repairing of tyres and tubes, and is disclosed, for example in WO 9704947. WO 97 04,947 relates to repair patches for inflatable articles such as inner tubes, beach toys, personal floatation devices, balloons. The patent, however, remains silent about the use of such patches for the repair of pneumatic tubes other than bicycle tubes. Tyre cannot be repaired by this adhesive. PSA's have the ability to quickly bond with the punctured surfaces due to their aggressively tacky nature at room temperature and are held firmly to the surface by inflating the tube inside the tyre. However, substantial bond strength is achieved only after attaining a temperature of 70°C due to the friction of wheel. These patches are advantageous as they are handy and can be carried as a spare. They do not require Chemical Vulcanizing Fluid (CVF) for activation nor heat for bond creation at room temperature. These are cost-effective. However, there are several disadvantages associated with the conventional patches containing pressure sensitive composition. The chief disadvantage is that the application of the patch is limited to the repair of cycle tubes only. The patches are marketed in strip 15 - 18 mm wide and 75 mm in length designed to repair only small puncture in cycles. Also, the load bearing capacity of such patches is less. On account of inherent limitations of these patches, their usefulness is restricted, only to cycles in mountains and limited to one passenger. An important component of a patch is the adhesive. It is the adhesive that imparts most of the binding strength to the patch. Thus, adhesives play an important role in the repair of damaged tyres. Several types of adhesives are available in the market, the most popular being the solvent based adhesive. This adhesive is marketed under the brand name "CVF" for patch and "TEM"adhesive VSC for retreading. At the time of use, this adhesive is applied to the patch followed by application of the solvent and thereafter, the patch is fixed or applied to the damaged surface. The disadvantage of this adhesive is the concurrent use of solvent which takes time to dry. Therefore, the end product, i.e. patch becomes quite expensive and requires time to dry causing environmental problems. U.S. Patent 5,395,879 describes an adhesive composition comprising styrene butadiene rubber along with certain additives. Similarly, US Patent 6,127,476 also discloses an adhesive composition suitable for use in patches for repair of damaged tyres. Each of these adhesive compositions are the adhesives suffer from several disadvantages, as discussed above. Therefore, there is a need for an adhesive which is economical, which can be easily applied and used on patches and is capable of sustaining heavy loads. The prior art lacks in an adhesive coated patch which is free from above problems and is economical and saves time with long shelf-life and can be easily applied by an unskilled person. Objects of the Invention The main object of this invention is to provide a novel versatile adhesive composition which can be coated on patches and suitable for repairing all kinds of damaged tubes and tyres. Another object of the invention is to provide an adhesive composition having long shelf-life. Yet another object of the invention is to provide an adhesive, which when applied to a patch is capable of curing automatically with the rise in the temperature of the tubes inside the tyres. Still another object of the invention is to provide an adhesive composition exhibiting excellent bond strength between the patch and tubes / tyre in minimum time, thus increasing the output and profitability of the retread and repair. Another object of this invention is to provide a novel adhesive composition that can be coated on patches used for repairing tyres and such patches have maximum load bearing capacity. Yet another object is to provide an adhesive composition for repair of all types of tyres, be if Trucks, buses, Earth moving Machinery Tyres, Agriculture Tractor Tyre or Large Trailor Tlyres. Statement of the Invention Accordingly, the invention provides A novel synergistic adhesive composition useful for bonding vulcanizable elastomeric rubbers to a substrate, said composition comprising 2-25% by weight of a styrenic block copolymer, 1-15% by weight of natural rubber, 13-40% by weight of tackifier resin, 1.5-3.5% weight of sulfur, 0.2 to 20% by weight of accelerator, 0.1 to 10% by weight of zinc oxide, 0.1 to 15% by weight of antioxidant and other conventional additives. The invention provides an adhesive composition that primarily consists of styrene block copolymer. Several block copolymers were screened by the applicants because the copolymer is the component providing bond strength in the adhesive. Hence, it is desirable to select a block copolymer having highest bond strength, with minimum saturation and also substantially unaffected by oxidation. Such a block copolymer, having high thermal stability as well as having an appropriate compatibility with the other ingredients of the composition may be selected from the family of styrenic block copolymers of A-B-A type. This family consists of polymers having terminal styrenic group and middle block of butadiene. Examples of such block copolymers are styrene isoprene styrene, styrene butadiene styrene. These thermoplastic elastomers in combination with other rubbers such as nuprene, chlorinated rubber, butyl rubber, chloro sulphonated polyethylene, etc. give excellent adhesion properties. The applicants have found that a block copolymer having a polystyrene block on both ends of the rubber mid-block are thermodynamically incompatible with the rubber mid block and therefore, on a microscopic scale, separate to form polystyrene domains thereby creating a physically cross-linked rubber network structure and this network imparts high cohesive strength to the rubber. The most preferred block copolymer is styrene isoprene styrene. The amount of the styrenic block copolymer that may be present in the adhesive composition is usually in the range of 2 to 25% by wt. The amount of such a styrenic block copolymer to be added can be readily determined by a person skilled in the art based on factors such as compatibility and ratio of other ingredients used in the composition, the bond strength required etc. In addition to the styrenic block copolymer, natural rubber is used in the adhesive composition. The rubber used may preferably be isoprene natural rubber; the content thereof being 1-15% by wt. Apart from the styrene co-polymer and the rubber, the adhesive composition also contains tackifiers. The tackifiers suitable for use in the adhesive composition are aromatic hydrocarbon and polyterpene based tackifiers. Hydrocarbon based tackifiers are end block tackifiers whereas polyterpenes are mid-block tackifiers. Another function of the tackifiers is to render the adhesive tacky so that appropriate adhesion with the substrate is achieved. The tackifier resin used in the composition, is selected from hydrocarbon resins - Petrez, Caprez, etc., polyterpenes - Rosin Esters (glycerol esters), Phenolic compounds -Phenol formaldehyde, Resorcinolformaldehyde, Coumarone -indene resins, glycerol esters, etc. The amount of the tackifiers resin used may be in the range of about 13-40% by wt. The composition also uses accelerators selected from the classes thiazoles, thioureas, thiocarbamates, sulphonamides and aldehyde amines. The thiazoles are selected from the group comprising 2-Mercaptobenzothiazole (MET), Dibenzothiazole disulphide (MBTS) and Zinc mercaptobenzothiazole 2MBT). Sulphonamide accelerators are such as N- Cyclohexyl benzothiazole- 2- Sulphenamide (CBS). Thiurans are such as Tetramethyl thiuramdisulphide (TMTD) and Dipentamethylenethiuram tetrasulphide (DPTT). Dithiocarbamates are selected from Zinc deethyldithiocarbamate (ZDC), and Zinc dibutyldithiocarbamate (ZDBC). Guanidine accelerators are such as Diphenylguanidine (DPG) and Di-ortho-tolylguanidine (DOTG). Various additives such as fillers, pigments, dispersion aiding agents, viscosity controlling agents, antioxidants, reinforcing agents etc. as are known in the art may be included in the composition. Fillers include finely divided materials like carbon black, silica, titanium dioxide, zinc oxide, etc. The fillers and additives constitute about 0.1 to 15% by wt. of the adhesive composition. Another important ingredient of the adhesive composition is sulfur, sulfur containing compounds and organic peroxides.. It enables formation of crosslink bonds. The content of sulfur in the composition may vary from 1.5 - 3.5%. The antioxidants used are hindered phenols, phosphites, hydroquinones and amines. In fact, the prior art is replete with instances of different types of adhesive compositions suitable for use in various patches have been described. Each adhesive composition is different from the other in terms of the ingredients used and/or the ratio and proportion in which they are used. In fact, the selection of specific ingredients in a specific amount and ratio decides the bond strength of the adhesive. It is this selection of ingredients in this specific combination that imparts novelty to the adhesive composition. Further, the adhesive composition of the present invention is not a mere mixture. On the other hand, the composition is a synergistic composition exhibiting surprising and unique properties. When applied to a patch and when the patch is used on vehicle tyres, the adhesive gets cured and therefore, the patch exhibits excellent bond strength. The synergistic property is observed when the adhesive composition is applied to a patch and vulcanization takes place. The adhesive composition so prepared has excellent bond strength ranging from 20 60 lbs. It is versatile, in that it can be used for adhesion to a variety of rubber-based substrates, such as vehicle tyres. In general, the adhesive is applied to any surface and dried. The amount of adhesive used depends on the application method, the material or substrate to which adhesion is sought and the material to which applied. Drying may be accomplished under ambient conditions such as room temperature. But, the preferred practice is the use of heat of about 50° C to 200° C or so. Drying under room temperature may take 12 - 30 hours whereas drying under heat takes about 2 to 10 minutes. The adhesive composition of the invention is not a mere collection of different ingredients. It is a synergistic composition wherein the ingredients have been selected with great care and are taken in proportions such that excellent bond strength is imparted to the adhesive composition. Thus, the composition is not a mere admixture and exhibits surprising and unexpected properties. As mentioned in the earlier sections, it is now a common practice to use patches to repair damaged tyres and tubes. In such cases, a patch of size and structure appropriate to cover the damaged portion of the tyre is selected. Usually, such patches are made of rubber or similar vulcanizable elastomeric material. These patches are designed in a manner such that the centre is padded and has greater thickness than the edges. A typical patch comprises (a) a backing substrate and (b) an adhesive layer coated on said backing substrate. The backing substrate generally comprises vulcanizable elastomeric material. The patch is then similarly positioned and applied to the damaged portion of the tyre/tube such that it covers the entire damaged portion. The repaired tyre is put back in vehicle for use, where the repair is automatically cured by the heat generated inside the tyre due to the friction of the running tyre and road, in situ or given to the owner for letting it cure at normal ambient temperature. The process for the preparation of synergistic adhesive composition of the invention is fairly simple and comprises the following steps: a) milling 1-15% by wt. natural rubber and 2-25% by wt, co-polymer to obtain a softened mass; b) adding 1.5-3.5% wt. of sulphur, 0.1-3% by wt. organic peroxide, 0.2 to 5% wt. of accelerator, 0.1 to 10% wt. zinc oxide and 0.1 to 5% wt. antioxidant to the softened mass of step (a) to obtain a homogeneous mass; c) dissolving the homogenous mass in an organic solvent to obtain a first solution A; d) dissolving 13-40% by wt. tackifier resin in an organic solvent to obtain second solution B; and e) mixing solutions A and B to form a homogenous solution and allowing it to mature for 6-24 hrs. to obtain an adhesive composition. The organic solvent in steps (c) and (d) is selected from the group of aromatic solvents such as toluene, xylene, methyl ethyl ketone, food grade hexane and chlorinated solvents. It is observed that during the process of the preparation of the novel adhesive composition, no chemical reaction takes place. In fact, the novel synergistic qualities/properties are observed only after curing of the elastomeric substrate to which it is applied. The invention is illustrated by the following figures: 1. Figure-1 is a graphical representation of the drying time taken by the composition of the invention. 2. Figure-2 is a graphical representation of the repair time taken by the composition of the invention as compared to conventional compositions. 3. Figure-3 is a graphical representation of the bond strength of the composition of the invention as compared to the conventional compositions. The invention is illustrated by the following examples, which should not be construed as limitations on the inventive scope of the invention. The invention is not limited to the exact details of the composition etc. as set out hereunder and described. Variations, obvious to one skilled in the art, are deemed to be included within the scope of the invention. EXAMPLE 1 18.35 grams of SIS rubber was mixed with 6.58 grams of natural rubber, 34.33 grams of tackifiers, 4.29 grams of sulphur, 1.28 grams of zinc diethyl dithiocarbamate, 14.29 grams of zinc oxide, 6.43 grams of polymerized 2,2,4,trimethyl-l,2-dihydro quinoline, with balanced quantity of Aromatic solvent were added together and mixed to obtain an adhesive composition. EXAMPLE 2 10.7 grams of SIS rubber was mixed with, 4.5 grams of natural rubber, 15.3 grams of tackifiers, 48 grams of sulphur, 0.5 grams of peroxide, 3 grams of zinc diethyl dithiocarbamate, 6 grams of zinc oxide, 8 grams of polymerized, 2,2,4-trimethyl-l,2-dihydroquinoline with balanced quantity of Aromatic solvent were added together and mixed to obtain an adhesive composition. EXAMPLES 18.3 grams of NR was mixed with, 12 grams of SBS, 38.4 grams of tackifiers^ 6.49 grams of Tetra methyl uram disulphide, 3.4 grams of cumyl peroxide, 3 grams of zinc dibutyl di thiocarbamate, 3.5 grams of zinc oxide, 5.0 grams of 2,4 di (alpha phenyl - ethyle) phenol with balanced quantity of aromatic solvent were added together and mixed to obtain an adhesive composition. EXAMPLE 4 12 grams of NR was added with 8 grams of neoprene, 5 grams of SIS and 3 grams of chlorinated NR, 38 grams tackifier 5.0 grams of Sulphur, 3.0 grams of 2,mercaptobenzo thiozole, 5.5 grams of zinc oxide, 6.0 grams polymerized 2,2,4- trimethyl, 1,2 dihydro quinoline with balanced quantity of aromatic solvent were added together and mixed to obtain an adhesive composition. The adhesive composition prepared according to the aforementioned examples was subjected to a series of tests to evaluate its bond strength and whether it is suitable for use in patches for repair of damaged tyres. A comparison of the adhesive composition of the invention vis-s-vis conventional compositions is set out in Table 1. Test methods and results The following test methods were used to measure the various test results. a. Inflator Tests - This test is performed to determine the gripping tendency of the patch with tube surface. One circular pad of cured rubber sheet of standard thickness is taken and hole is punched at center with the help of a die. The surface around the hole is buffed and cleaned with the help of cleaning media. A patch containing the adhesive composition of the invention is applied onto the damaged areas following all necessary precautions. This pad is then fitted on the infiator and blown with the help of air at 5 to 8 psi of pressure. No slippage is allowed within half an hour of inflation. It was found that slippage was within the permissible limits of 5% within 4 hours. b. Tyre patch adhesion testing - This test is performed for tyre patch to determine the bond strength developed between tyre surface and the patch. A substrate (replica for inner surface of tyre) is prepared. The surface of substrate is buffed and cleaned. The patch containing the adhesive composition of the invention is fixed over the substrate. The whole assembly is cured at room temperature. The separating force between patch and substrate after cutting the assembly to 1" width is measured in KMI make tensile tester. Patches meet the minimum requirement of 3 kg per centimeter of width. c. Shelf life testing - This test is done by physically placing these repair patches in the normally prevailing climate and storage for all type of patch. This testing indicates very satisfactory shelf life condition of the patch. Accordingly, a patch containing the adhesive composition of the invention was kept in the open at the room temperature for about 8 months. The patch was found to be effective under conditions described in (a) and (b) above even after 8 months. Further, the patch containing the adhesive composition of the invention was kept in an oven at certain elevated temperature. The samples were taken out after a period of 6-8 months. A prick test was carried out to determine the condition of the adhesive layer. It was found that the patch did not give way on account of constant use. The above tests indicate that the adhesive composition has a shelf life of not less than 8 months. EXAMPLE 5 In addition to the above, comparative tests were conducted in respect of the adhesive compositions in order to test the following three parameters in comparison with the commonly available compounds USC and CVF: (i) Drying time (ii) Tyre repair time (iii) Bond strength The adhesive composition of the invention was applied on a patch. Similarly, commonly available compounds USC and CVF were also applied to the patch and the drying time was noted. It was found that the adhesive compositions took only 2 minutes to dry whereas CVF and USC took around 13 minutes and 18 minutes respectively. A graphical representation of the drying time taken by the respective compounds is shown in the graph at figure-1. The tyre repair time was tested in the following manner: (a) The conventional method for repairing the damaged tyres involves making of a cavity at the spot where the damage occurred. The cavity is such that the diameter at the top of the cavity is greater than the diameter at the bottom of the cavity. In other words, the cavity is large at the surface of the tyre and tapers down. According to the conventional method, the cavity is filled with the vulcanizing fluid and the repair gum upto the top, i.e. the filling is effected in a manner such that it fills the cavity and levels up with the surface of the tyre. This tyre whose cavity is so filled, is put in a spotter wherein the filling in the cavity cure in two hours. After the temperature is raised to 80°C. The tyre is then taken out, the inner surface thereof coated with CVF and the patch is applied on the damaged portion of the tyre and thereafter the tube is inserted in the tyre. On the other hand, when the tyre is repaired according to the method of the invention, the cavity in the damaged portion of the tyre is filled with filler compounds. Once the filling is effected, the patch coated with the adhesive composition of the invention is applied to the damaged portion of the tyre and allowed to cure. The entire time taken for repair of the tyre is much less than the conventional method. The time taken for repair of the tyres of different vehicles is shown in the graph in figure-2. As can be seen from the figure, the repair time taken in the method of the invention is significantly less than the conventional methods. (b) Figure-3 represents a graph showing the bond strength of the adhesive composition of the invention as compared to the compounds USC and CVF which are conventionally used for repair of damaged tubes and tyres. As can be seen from the figure, the bond strength of the adhesive composition is much higher than the bond strength of the conventional compounds. TABLE-1 COMPARISON CURRENT METHODS OF TYRE/TUBE REPAIR AND NOVEL ADHESIVE (Table Removed) WE CLAIM 1. A novel synergistic adhesive composition useful for bonding vulcanizable elastomeric rubbers to a substrate, said composition comprising 2-25% by weight of a styrenic block copolymer as hereindescribed, 1-15% by weight of natural rubber, 13-40% by weight of tackifier resin as hereindescribed, 1.5-3.5% weight of sulfur, 0.2 to 20% by weight of accelerator as hereindescribed, 0.1 to 10% by weight of zinc oxide, 0.1 to 15% by weight of antioxidant as hereindescribed and other conventional additives. 2. A composition as claimed in claim 1, wherein the styrenic block copolymer is selected from styrene butadiene styrene, styrene isoprene styrene, neoprene, chlorinated rubber, butyl rubber and chloro-sulphonated rubber. 3. A composition as claimed in claim 1, wherein the natural rubber is an isoprene natural rubber. 4. A composition as claimed in claim 1, wherein the tackifier resin is selected from hydrocarbon resins, polyterpene based resins, phenolic compounds, coumarone - indene resins and glycerol esters. 5. A composition as claimed in claim 1, wherein the accelerator are selected from the classes of thiazoles, thioureas, thiocarbamates, sulphenamides, dibutyl dithiocarbamate, zinc diethyl thiocarbamate and aldehyde amines. 6. A composition as claimed in claim 5, wherein the thiazole accelerator is selected from the group comprising 2-Mercaptobenzothiazole (MBT), Dibenzothiazole disulphide (MBTS) and Zinc mercaptobenzothiazole ( 2MBT). 7. A composition as claimed in claim 5, wherein the sulphonamide accelerator is selected from N- Cyclohexyl benzothiazole- 2- Sulphenamide (CBS). 8. A composition as claimed in claim 5, wherein the thiurans is selected from Tetramethyl thiuramdisulphide (TMTD) and Dipentamethylenethiuram tetrasulphide (DPTT). 9. A composition as claimed in claim 5, wherein the dithiocarbamate is selected from the group comprising Zinc deethyldithiocarbamate (ZDC), and Zinc dibutyldithiocarbamate (ZDBC). 10. A composition as claimed in claim 5, wherein the guanidine accelerator is selected from Diphenylguanidine (DPG) and Di-ortho-tolylguanidine (DOTG). 11. A composition as claimed in claim 4, wherein the hydrocarbon resin is selected from petrez, caprez, polyterpenes-Rosin Esters and glycerol esters. 12. A composition as claimed in claim 4, wherein the phenolic compound is selected from phenolic compounds such as Phenol formaldehyde, Resorcinolformaldehyde, Coumarone -indene resins and glycerol esters. 13. A composition as claimed in claim 1, wherein said antioxidant is selected from hindered phenols, phosphites, hydroquinones and amines. 14. A composition as claimed in claim 1 wherein the additives are selected from carbon black, silica, zinc oxide, titanium oxide, filler, dispersion aiding agents, viscosity controlling agents and reinforcing agent. 15. A composition as claimed in claim 1 wherein the fillers selected from the class of finely divided materials such as carbon black, silica, titanium dioxide and zinc oxide. 16. A process for preparing a synergistic adhesive composition as claimed in claim 1 comprising the steps of: a) milling natural rubber and a co-polymer for about 5 minutes to soften the mass; b) adding finely divided copolymer 2-25% by wt, 1-15% natural rubber; 1.5- 3.5% wt. of sulphur, 0.1-3% by wt. organic peroxide, 0.2 to 5% wt. of accelerator, 0.1 to 10% wt. zinc oxide and 0.1 to 5% wt. antioxidant, to the mass of step a) to obtain a homogeneous mass; c) dissolving the homogenous mass in an organic solvent to obtain a solution A; d) dissolving 13-40% by wt. tackifier resin in an organic solvent to obtain second homogenous mass B; and e) mixing A and B and allowing it to mature for 6-24 hrs. to obtain the adhesive composition. 17. A process as claimed in claim 16, wherein the styrenic block copolymer is selected from styrene butadiene styrene, styrene isoprene styrene, neoprene, chlorinated rubber, butyl rubber and chloro-sulphonated rubber. 18. A process as claimed in claim 16, wherein the natural rubber is an isoprene natural rubber. 19. A process as claimed in claim 16, wherein the tackifier resin is selected from hydrocarbon resins, polyterpene based resins, phenolic compounds, coumarone - indene resins and glycerol esters. 20. A process as claimed in claim 16, wherein the accelerator is selected from the classes of thiazoles, thioureas, thiocarbamates, sulphenamides, dibutyl dithiocarbamate, zinc diethyl thiocarbamate and aldehyde amines. 21. A process as claimed in claim 20, wherein the thiazole accelerators selected from the group comprising 2-Mercaptobenzothiazole (MBT), Dibenzothiazole disulphide (MBTS) and Zinc mercaptobenzothiazole (2MBT). 22. A process as claimed in claim 20, wherein the sulphonamide accelerators are such as N- Cyclohexyl benzothiazole- 2- Sulphenamide (CBS). 23. A process as claimed in claim 20, wherein the thiurans are such as Tetramethyl thiuramdisulphide (TMTD) and Dipentamethylenethiuram tetrasulphide (DPTT). 24. A process as claimed in claim 20, wherein the dithiocarbamates are selected from the group comprising Zinc deethyldithiocarbamate (ZDC), and Zinc dibutyldithiocarbamate (ZDBC). 25. A process as claimed in claim 20, wherein the guanidine accelerators are such as Diphenylguanidine (DPG) and Di-ortho-tolylguanidine (DOTG). 26. A process as claimed in claim 16, wherein the tackifier resin is selected from hydrocarbon resins such as Petrez, Caprez, polyterpenes-Rosin Esters (glycerol esters), and Phenolic compounds such as Phenol formaldehyde, Resorcinolformaldehyde, Coumarone -indene resins and glycerol esters. 27. A process as claimed in claim 16, wherein said antioxidant is selected from hindered phenols, phosphites, hydroquinones and amines. 28. A process as claimed in claim 16, wherein one additives are selected from carbon black, silica, zinc oxide, titanium oxide, fillers, dispersion aiding agents, viscosity controlling agents and reinforcing agents. 29. A process as claimed in claim 16, wherein the fillers selected from the class of finely divided materials such as carbon black, silica, titanium dioxide and zinc oxide. 30. A patch comprising: (a) a backing substrate as hereindescribed and (a) an adhesive layer comprising an adhesive composition as claimed in claims 1-14 coated on at least one side of the said backing substrate. 31. A patch as claimed in claim 30, wherein the backing substrate as hereindescribed comprises vulcanizable elastomeric material. 32. An adhesive composition substantially as herein described with reference to the examples. 33. A process for the preparation of an adhesive composition substantially as herein described and illustrated. 34. A patch substantially as herein described and illustrated with reference to given examples and drawings.

Documents:

57-del-2001-abstract.pdf

57-del-2001-assignment.pdf

57-del-2001-claims.pdf

57-del-2001-correspondence-others.pdf

57-del-2001-correspondence-po.pdf

57-del-2001-description (complete).pdf

57-del-2001-drawings.pdf

57-del-2001-form-1.pdf

57-del-2001-form-13.pdf

57-del-2001-form-18.pdf

57-del-2001-form-2.pdf

57-del-2001-form-26.pdf

57-del-2001-form-3.pdf

57-del-2001-form-5.pdf

57-del-2001-form-6.pdf