Title of Invention

"A PROCESS FOR PREPARATION OF EPOXY-RESIN BASED STRUCTURAL PUTTY"

Abstract

A process for preparation of epoxy-resin based structural putty comprising of preparing epoxy paste by compounding epoxy resin with filler as herein described, plasticiser as herein described, and colourant as herein described. Preparing hardener by dissolving an amine as herein described in a solvent as herein described, if amine is in solid form, otherwise amine as such is used as hardener, mixing as herein described of epoxy paste and hardener.

Full Text

FIELD OF INVENTION Present invention relates to a process for preparation of putty and more particularly to a process for preparation of epoxy resin based structural putty. PRIOR ART A putty composition is utilised for joining rubber to metal, metal to metal, for filling gaps between joints and for leveling of uneven surfaces. Putty compositions comprise high level of filler materials and in general these are highly viscous/paste like mass. Available putty compositions are based on either silicone resin or epoxy resin. The adhesive capability of a putty composition is regarded good if the resultant bond has a lap shear of at least 3 MPa. A putty for excellent results should be flexible, tough and curable by cross linking with minimum shrinkage under ambient conditions. Silicon resin based putty compositions are basically low strength and highly flexible materials, whereas, epoxy resin based putty compositions are basically high strength and low flexible materials, putty, compositions based "on epoxy resins, in general, suffer from following limitations. Primary limitation of putty compositions based on epoxy resin and amine terminated liquid polymer, known in the art, is that these putty compositions do not have very high adhesion strength. Another limitation of putty compositions based on epoxy resin and amine terminated liquid polymer, known in the art, is that these putty compositions do not have enough cohesive strength to bear high load. Yet another limitation of putty compositions, known in the art. is that these material have limited applications because of their high viscous/paste like characteristic. As a result, these compositions cannot be brushed on surfaces and applied on areas having narrow opening. OBJECT OF THE PRESENT INVENTION Primary object of the present invention is to provide a process of ' preparing a putty composition, which can be applied on wide range of; surfaces and shapes by cold method. Another object of the present invention is to provide a process of preparing a putty composition, which has high adhesive strength. Yet another object of the present invention is to provide a process of preparing a putty composition which can be utilised for adhering special rubber to metal and metal to metal. Still another object of the present invention is to provide a process of preparing a putty composition , which can bear high load. Further object of the present invention is to provide a process of preparing a putty composition, which is not brittle. Still further object of the present invention is to provide a process of preparing a putty composition, which can be cured at ambient condition without application of external heat. Yet further object of the present invention is to provide a process of preparing a putty composition, which has good flexibility. Still further object of the present invention is to provide a process of preparing a putty composition, which has excellent weather resistance. Even further object of the present invention is to provide a process of preparing a putty composition, which has excellent resistance to marine environment. Still further object of the present invention is to provide a process of preparing a putty composition, which has minimal air entrapment. Yet further object of the present invention is to provide a process of preparing a putty composition, which can be modified with suitable filler material for obtaining improved functional properties. Even further object of the present invention is to provide a process of preparing a putty composition, which is cheap, simple and easy to adopt. SUMMARY OF THE INVENTION According to this invention there is provided a process for preparation of epoxy-resin based structural putty characterised by the steps of :- a) preparing epoxy paste by compounding epoxy resin with filler as herein described, plasticiser as herein described, and colourant as herein described, b) preparing hardener by dissolving an amine as herein described in a solvent as herein described, if amine is in solid form, otherwise amine as such is used as hardener, c) mixing as herein described of epoxy paste and hardener. In accordance with present invention, there is provided a process for preparing structural putty which has high strength, good weather resistance. The proposed putty composition basically comprises two parts. One part (epoxy paste) contains epoxy resin, filler, pigment and plasticizer while the other part (hardener) contains an amine. The complete putty composition comprises in equivalent of at least one epoxy resin, and about 0.8 to 1.5 equivalent of amine having a carbon-carbon backbone. The proposed putty composition results in very strength when applied between various metal as well as rubber surfaces. The proposed putty composition is easy to apply on all shapes and is highly resistant to open air as well as marine environment. The process of preparing putty composition comprises the steps of preparation of epoxy paste, preparation of hardener solution, final mixing of epoxy paste and hardener. DESCRIPTION OF THE PRESENT INVENTION The process of preparing putty composition comprises of following stepss (i) Preparation of epoxy paste; In the epoxy paste, the epoxy resin used may be liquid or low melting solids but preferably liquids having a bulk viscosity from about 100 to about 2,000,000 centipoises and more preferably from 5000 to 50,000 centipoise (measured using a Haake rotoviscometer at 250C). The epoxy resin can have equivalent weight from 100 to 2000, more preferably from 100 to 1000. There are various epoxy resins available commercially but epoxy resin based on diglycidyl ether of bisphenol—A is preferred. The epoxy resin is compounded with various fillers such as carbon black, talc, silicates, and plasticizer such as phthalates, sehacates, trimellitates, and colourants like metal oxides. The compounding is done by using a triple roll mill at ambient conditions. (ii) Preparation of hardener The hardener basically comprises amine, which in turn acts as cross-linker during mixing of epoxy paste and hardener. Amine is preferably an aliphatic diamine. If it is a liquid, it can be directly used and if it is a solid, the amine is dissolved in a suitable solvents like alcohol. Epoxy paste should be stored in sealed tin containers whereas hardener should be stored in dark glass bottles. (in) Mixing of epoxv paste and hardener Epoxy paste (1 equivalent) is mixed with hardener (1 equivalent) immediately prior to application on actual surfaces under ambient conditions. The process of the present invention will now be illustrated with working examples which are intended to be typical examples to illustrate the working of the invention and are not intended to be taken restrictively to imply any limitation on the scope of the present invention. WORKING EXAMPLES Example 1 The epoxy resin used in the present example is a diglycidyl ether of bisphenol A from Ciba Geigy. There are various grades available having different equivalent weight. A blend of two grades of epoxy resin namely GY280 (equivalent weight 245 to 255) and GT7071 (equivalent weight 500 to 525) is used in the present case. Resin GY280 is viscous liquid (10.000 to 12,000 cps at 25°C) whereas resin GT7071 is solid at room temperature. Prior to mixing of various ingredients both grades of epoxy resin are blended in suitable proportion (GY/280/GT6071 82/18) in a resin kettle under stirring at 80°C. Subsequently, the epoxy resin blend (5.0 parts by weight), talc as filler (40 parts by weight), red iron oxide as pigment (2 parts by weight) and dibutyl phthalate as plasticiser (8 parts by weight) are mixed in a triple roll mill. Hardener is prepared by dissolving hexamethylene diamine (50 gm) in ethyl alcohol (50gm). Finally, 100 gm of epoxy paste and 9.6 gm of hardener prepared in above manners are mixed immediately prior to application on various work surfaces. Example 2 The epoxy resin used in the present invention is a diglycidyl ether of bisphenol A from Ciba Geigy. There are various grades available having different equivalent weight. A blend of two grades of epoxy resin namely LY556 (equivalent weight 175 to 195) and GT7071 (equivalent weight 500 to 525) is used in the present case. Resin LY556 is a liquid (8,000 to 10,000 cps at 25°C) whereas resin GT7071 is a solid at room temperature. Prior to mixing of various ingredients both grades of epoxy resin were blended at a suitable proportion (LY556/GT7071 65/35) in a resin kettle under stirring at 80°C. Subsequently, the epoxy resin blend (50 parts by weight), talc as filler (40parts by weight), red iron oxide as pigment (2parts by weight) and dibutyl phthalate as plasticiser (8parts by weight) are mixed in a triple roll mill. Hardener is prepared by dissolving hexamethylene diamine (50 gm) in ethyl alcohol (50gm). Finally, 100 gm of epoxy paste and 9.6 gm of hardener prepared in above manners are mixed immediately prior to application on various work surfaces. The resultant putty compositions, prepared in above manner are tested for its adhesion properties. The adhesion test is done by applying the putty onto two cylindrical metal dolly (Dia 25mm). After complete curing, the specimen is tested for pull strength. Similarly, lap shear test is also carried out as per ASTMD 1002 by applying the putty on various metal surfaces. The adhesion behaviour of the composition is also tested with respect to rubber-metal specimen. The properties of the compositions and strength behaviour have been listed below. (Table Removed) It is clear from the above table, that the putty compositions prepared in above manner can be applied onto various types of surfaces with excellent bonding characteristics. It is to be understood that the process of present invention is susceptible to adaptations, changes, modifications by those skilled in the art. Such adaptations, changes, modifications are intended to be within the scope of the present invention which is further set forth by following claims. WE CLAIM; 1. A process for preparation of epoxy-resin based structural putty characterised by the steps of:- a) preparing epoxy paste by compounding epoxy resin with filler as herein described, plasticiser as herein described, and colourant as herein described, b) preparing hardener by dissolving an amine as herein described in a solvent as herein described, if amine is in solid form, otherwise amine as such is used as hardener, c) mixing as herein described of epoxy paste and hardener. 2. A process as claimed in claim 1 wherein epoxy-resin preferably used is liquid resin based on diglycidyl ether of bisphenol-A. 3. A process as claimed in claim 1 wherein liquid epoxy resin has bulk viscosity from 100 to about 2,00,000 centipoises, more preferably from 5000 to 50, 000 centipoise at 25° C. 4. A process as claimed in claim 1 wherein epoxy resin has equivalent weight from 100 to 2000 more preferably from 100 to 1000. 5. A process as claimed in claim 1 wherein said filler used for said compounding of resin is for example carbon black, talc, silicates as herein described. 6. A process as claimed in claim 1 wherein plasticiser used for said compounding of epoxy resin is for example phthalates, sebacates and trimellitates as herein described. 7. A process as claimed in claim 1 wherein colourant used in said preparation of epoxy paste is a metal oxide for example red iron oxide. 8. A process as claimed in claim 1 wherein epoxy paste for use in a hardener comprising epoxy resin with filler, plasticizer and colourant. 9. A process for preparation of epoxy-resin based structural putty as substantially described and illustrated herein.

Documents:

317-del-2000-abstract.pdf

317-del-2000-claims.pdf

317-del-2000-correspondence-others.pdf

317-del-2000-correspondence-po.pdf

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

317-del-2000-form-1.pdf

317-del-2000-form-19.pdf

317-del-2000-form-2.pdf

317-del-2000-form-3.pdf

317-del-2000-gpa.pdf