Title of Invention

"A STRUCTURAL ADHESIVE"

Abstract

This invention relates to an improved adhesive comprising of two components -component A and component B, in equal proportions wherein: (a) component A comprises 5 to 50% by w/w of rubber such as herein described and 2-50% of aromatic amine such as herein described in 65-85% of ethyl acetate, and (b) component B comprises 20-40% w/w of an epoxy resin or blend of two epoxy resins in 60-80% w/w of ethyl acetate, and a metal oxide selected from ZnO, MgO, Fe2O3.

Full Text

FIELD OF INVENTION This invention relates to a Inconsistent With titlt & cl-1 structural adhesive for applications as adhering of rubber to rubber, rubber to metal by cold method. PRIOR ART Adhesion between two surfaces metal to rubber, rubber to rubber is obtained by application of suitable adhesive material and allowing it to dry or cure. The adhesives presently used are based on various polymeric materials including epoxy resin. These adhesives have certain limitation One of the limitation of adhesives known in the art is that they have poor adhesion strength. Another limitation of the known adhesives is that they are very brittle. OBJECTS OF PRESENT INVENTION An object, of the present invention is to propose a process tor preparation of structural adhesive for joining particularly rubber to rubber and rubber to metal. Another object of the present invention is to propose a process for preparation of structural adhesive which is capable of adliesing rubber to rubber, rubber to metal by cold method without application of any external heat. Still another object of the present invention is to propose a process for preparation of structural adhesive which has higher adhesive strength Yet another object of the present invention is to propose a process for preparation of structural adhesive which is not brittle. Further object of the present invention is to propose a process for preparation of structural adhesive which has excellent weather resistance including marine environment. SUMMARY OF THE INVENTION According to this invention there is provided an improved adhesive comprising of two components -component A and component B, in equal proportions wherein: (a) component A comprises 5 to 50% by w/w of rubber such as herein described and 2-50% of aromatic amine such as herein described in 65-85% of ethyl acetate, and (b) component B comprises 20-40% w/w of an epoxy resin or blend of two epoxy resins in 60-80% w/w of ethyl acetate, and a metal oxide selected from ZnO, MgO, Fe2O3. The proposed adhesive composition is a two component system. The component A materials contain rubber, crosslinker for epoxy resin and ethyl acetate. The component B materials contain epoxy resin in ethyl acetate. The crosslinker for epoxy resin is an aromatic diamine. The rubber used is a carboxylated nitryl rubber. The epoxy resin is a blend of two grades of resins available commercially from (Ciba Gaigy) Ly556 and Gy280. DBSCRITPION OF INVENTION According to this invention there is provided a structural adhesive comprising of two components-component A and component B, in equal proportions wherein: (a) component A comprises rubber and aromatic amine in ethyl acetate, and (b) component B comprises an epoxy resin or blend of two resins in ethyl acetate, and a metal oxide. In accordance with the present invention, the structural adhesive comprises of two components, the component 'A' and component 'B' The process for preparation of each of these components and finally preparation of the adhesive therefrom, comprises of the following steps: (a) Preparation of Component 'A' of Adhesive; The component A' comprises of carboxylated nitrile rubber, cross—linker for epoxy resin and ethyl acetate. For preparation of this component, 5 to 5(37. by wt/wt preferably 10-20 by wt/wt of carboxylated nitrile rubber and 2 to 50"/., preferably 5—15% of an aromatic amine preferably m—phenylene diamine (required for curing epoxy resin in component 'B') are dissolved in ethyl acetate, under stirring by employing a high speed mechanical stirrer. The stirring is continued for about 8—10 hours until dissolution is complete. The component is stored in a dark glass bottle or is stored in a sealed tin container. * b) Preparation of Component 'B' of Adhesive; Component 'B' of adhesive of the present invention contains epoxy resin in ethyl acetate. For preparation of this component, preferably the percentage of epoxy resin in ethyl acetate is 20 to 90%, more preferably 60-80% by wt/wt. The epoxy resin may be liquid or low melting point solids but preferably liquids having a bulk viscosity from 100 cps to about 2,000,000 centipoises and more preferably from 5000 to 50,000 centipoises (measured using a Haake ro to viscometer at 25 C). The epoxy resin can have equivalent weight from 1000 to 2000, more preferably from 100 to 500. The epoxy resin preferably taken is based on diglycidyl ether of bisphenol A. In addition, stoichio-metric amount of metal oxide with respect to carboxyl content of carboxyl Nitrile rubber (XNBR) present in component A. The metal oxide taken is like ZnO, MgO. Fe203 but preferably ZnO is added to the component B The component B is also stored in a sealed tin container or dark glass bottle. (c) Preparation of Adhesive: The adhesive is prepared by mixing component A and component B in the ratio of 1:1. The present invention will now be more clearly understood from the example which follows. The example is not intended to be restrictive and is merely illustrative of the scope of the present invention. Preparation Of Pretreatment Solution: This solution is required only for rubber surface. This is a solution of dichloramine (N N' dichloro p-chloro benzene sulfonamide) in a solvent). The solvent for this solution is prepared by mixing 6 ml of distilled water in 100 ml of acetone. The pretreatment solution is prepared by dissolving about 14g of the above dichloramine in 100 ml of solvent. The above solution is prepared prior to application of adhesive. • WORKING EXAMPLE Component A is prepared by mixing 11 gm of carboxylated nitrile rubber and 11 gm of m-phenylamine dissolved in 78 gm of ethyl acetate All the ingredients are mixed thoroughly by employing a high speed mixer. Component B is prepared by dissolving diglycidyl ether of bisphenol A m ethyl acetate taking 80g of resin in 20g of ethyl acetate. A blend of two grades of epoxy resin namely Gy280 (equivalent wt 245 to 255) and Gy 250 (equivalent weight 182 to 192) is taken. All the components are mixed thoroughly by employing a high speed mixer. The component A and B were mixed together taking equal quantities of component 'A' and component 'B’. Application of Adhesive: The adhesive is applied onto the modified rubber surface and metal surface in three coats at a temperature of 23±5°C and relative hiniidity not exceeding 70%. The drying time of the first layer is 35±5 min, second layer is 25±5 min and third layer is 3±1 min. Afterwards the glued surfaces are stuck to each other without slipping. The specimens are rolled with the help of a roller weighing 500g at least ten times in each direction. The specimens are left for curing at room temperature for 72 hours. Adhesion Test of the Adhesive: The adhesion test is done by applying the adhesive onto rubber to rubber specimen and rubber to etal specimen (180x25x4mm3 ) The method of application is as per the procedure given above. After complete curing, the specimen was tested for 180° -peel strength. Properties of Structural Adhesive (Table Removed) WE CLAIM 1 . An improved adhesive comprising of two components -component A and component B, in equal proportions wherein: (a) component A comprises 5 to 50% by w/w of rubber such as herein described and 2-50% of aromatic amine such as herein described in 65-85% of ethyl acetate, and (b) component B comprises 20-40% w/w of an epoxy resin or blend of two epoxy resins in 60-80% w/w of ethyl acetate, and a metal oxide selected from ZnO, MgO, 2. An improved adhesive as claimed in claim 1 wherein rubber is preferably carboxylated nitrile rubber (XNBR) with acid value 40. 3. An improved adhesive as claimed in claim 1 wherein said aromatic amine is preferably m-phenylene. 4. An improved adhesive as claimed in claim 1 wherein for said component A, carboxylated nitrile rubber is preferably 10-20% by w/w. 5. An improved adhesive as claimed in claim 3 wherein said m-phenylene is preferably 5-15% by wt/wt. 6. An improved adhesive as claimed in claim 1 wherein for said component A, ethyl acetate is preferably 70-80% by w/w. 7. An improved adhesive as claimed in claim 1 wherein said epoxy resin is preferably epoxy-resin based on diglycidyl ether of bisphenol A. 8. An improved adhesive as claimed in claim 1 wherein the equivalent weight of epoxy resin is from 100 to 2000, preferably from 100 to 500. 9. An improved adhesive as claimed in claim 1 wherein for preparation of component B, the said metal oxide is preferably ZnO in stoichiometric amount to epoxy resin. 10. An improved adhesive substantially as described and illustrated herein.

Documents:

318-del-2000-abstract.pdf

318-DEL-2000-Claims.pdf

318-del-2000-complete specification [granted].pdf

318-DEL-2000-Correspondence-Others.pdf

318-del-2000-correspondence-po.pdf

318-del-2000-description (complete).pdf

318-del-2000-form-1.pdf

318-del-2000-form-19.pdf

318-del-2000-form-2.pdf

318-del-2000-form-3.pdf

318-DEL-2000-GPA.pdf