Title of Invention

"A PROCESS FOR TEMPORARY PAD PRINTING/REPRINTING ON AN UNEVEN SURFACE OF A GLASS CONTAINER"

Abstract

This invention relates to temporary pad printing on an uneven outer surface of a glass container using organic ink with colour(s) and shade(s) of any quality and hardener, removing that temporary print from its surface and again doing temporary pad printing on the uneven outer surface of same glass container using organic ink with colour(s) and shade(s) of any quality and hardener. The process for removal of temporary printing from the surface of glass container comprises preferably five-stage treatment consisting of first washing the containers by passing through water at normal climatic room temperature; passing through a mixture of hot water between normal temperature to 60°C and 1-2.5% sodium hydroxide; passing through mixture of hot water at temperature in the range between 60-80°C and 2.5 to 7% sodium hydroxide and optionally in the presence of an additive like SU; passing through a mixture of hot water at the temperature between normal temperature to 60°C and 1-2.5% sodium hydroxide, and finally with water at normal climatic room temperature, wherein the water preferably used is soft water. Alternately any chemical which can remove the printed matter, may be used, in lieu of sodium hydroxide. The increase or decrease in temperature from one stage to another stage does not exceed 40° to 42°C and is very well within the permissible limits of thermal shock resistance to prevent cracking of glass surface.

Full Text

FIELD OF INVENTION This invention relates to a process for temporary pad printing/ reprinting on an uneven outer surface of a glass container. The invention has particular beneficial use for industries using glass containers for packaging their products. Such industries would like to use glass containers again and again for filling of different products or same product in order to save their capital investment. The invention is also useful for printing additional matter, whenever required, on uneven glass surfaces which may be bearing permanent printed matter by any methods like screen printing such as silk screening, ACL(Applied Colour Labelling) method, etc. The additional matter, which may from time to time, be required to be printed on a glass surface, may be promotional ad 'like 'buy one, get one' or may be changed price whenever price change occurs, or may be a pircture logo relating to a forthcoming event like a festival. The invention is specifically very beneficial for small scale industry with low capital investment who may like to use the same containers for different products, or use it for one product at one time and later use it for different product or to use the left-over stock of glass containers bearing temporary printed matter, for different product, by pad printing new matter relevant to the product to be later packaged therein. PRIOR ART Glass containers used for packaging generally bear printed matter, trademark, pictures, designs and the like. Such printed matter is generally relevant for a specific product packed in the glass container. There are different methods known in the art for decorating outer surface of a glass container by printing on the glass surface. These include screen printing like silk printing, ACL (Applied Colour Labelling), decal applying. Broadly speaking, these methods silk printing, ACL , Decal printing, require that the colours used for printing should be thermally bondable to the glass to withstand handling of the container. The colours should not get partially or wholly removed by whatever type of rinse or detergent wash. The colours used for printing, therefore, generally incorporate special high temperature activated binders by which the colouring ingredients are bonded to the glass surface. Such heat activated binders are either inorganic such as ceramic like glass frit, as in the case of Applied Colour Labelling (ACL) or may be organic (US patent No. 4,074,363). An organic binder requires to be heated to about 350 to 550°F for bonding the colours to the glass surface whereas inorganic binders like glass frit require heating schedules over 800°F, more typically at 1100-1200°F. In the silk screening method (US patent No. 4,074,363), the colours used for printing are generally in the form of a viscous paste. These are applied by pressing or squeezing on a stencil in the form of a fine screen, which is placed on the surface of the glass container. When the screen is separated from the container, the coloured printed matter remains on the container over the delineated area. For permanent bonding, the glass containers are subjected to heating process. The offset printing process is generally used to apply organic colours (US patent No. 4,074,363). In decal applying (US patent No. 4,074,363), the colours to be used for printing, are carried on a temporary backing sheet, which is generally paper, on to which the colour layer is adhered by wax. The , colours generally used are inorganic. The other side of the backing sheet is also coated with a layer of wax or other suitable heat effective adhesive which enables temporary adhering of the colour layer to the glass container, prior to permanent bonding. On heating to 225 to 300°F, the decals get released from the backing and get temporarily adhered to the surface of glass container. On further heating to about 8000F, the printed matter in colour, gets permanently bonded to the glass container. The above methods have several disadvantages. A disadvantage of the above method is that the colours used for printing are costly. Another disadvantage of the above methods is that after heating, the printed matter in colour, gets permanently bonded to the glass surface and becomes part of the glass. Still another disadvantage of the above methods of printing, is that these methods require expensive equipments and machinery. Further disadvantage of the above methods of printing is that matter once printed on a glass surface cannot be removed and therefore no change can be made to the matter already printed on the glass surface. Still further disadvantage of the above methods is that these require heating chamber/lehar for heating to a high temperature for permanent bonding of coloured printed matter to the glass surface. Yet further disadvantage of the above methods is that in case of change in the printed matter that may be necessitated for statutory warning, promotional ad or any policy guidelines laid down by Government, the existing stock of glass containers would have to discarded causing huge avoidable expenditure. OBJECTS OF PRESENT INVENTION An object of the present invention is to propose a temporary pad printing on the uneven outer surface of same glass container, which may or may not be already bearing printed matter. Another object of the present invention is to propose a process of temporary pad printing on uneven outer surface of same glass container, by removing the temporary printed matter thereon and reprinting the matter, which may be same or different. Still another object of the present invention is to propose a process which is repeatable any umber of times. Further object of the present invention is to minimize the cost in decoration of uneven outer surface of a glass container. STATEMENT OF INVENTION According to this invention there is prov ided a process for temporary pad printing/reprinting on an uneven outer surface of a glass container wherein said temporary pad print comprises a mixture of known organic ink/ colours/ shades, solvent and optionally a hardner. and wherein said reprinting on an uneven outer surface of a glass container bearing temporary pad printed matter characterised in that steps of: (a) removing temporary pad printed matter from the outer uneven surface of the glass container by a five stage process involving a first stage of washing with water at ambient temperature, second stage of passing the containers through a mixture of hot water at temperature upto 60°C and sodium hydroxide, third stage of passing the container through a mixture of hot water at temperature between 60-80°C and sodium hydroxide, fourth stage of washing with hot water at temperature upto 60°C and fifth stage of washing the containers with water at ambient temperature, temperature gradient from one stage to another not exceeding 40 to 42°C, the concentration of sodium hydroxide during said second stage is 3-4% and concentration of sodium hydroxide during said third stage is 4-7%; (b) temporary pad printing on the outer uneven surface of the glass container with a temporary pad print, wherein the ratio between ink/colours/shades and hardner is 5 : 0.01 to 2 by wt. and the solvent is in amount of 5 to 40%. According to another embodiment a process of temporary pad printing/reprinting on uneven outer surface of a glass container, which according to another embodiment applicable to glass containers bearing permanent printed matter and requiring additional matter to be printed thereon, comprises, for printing, step of pad printing using mixture of organic ink, colour, shades and a hardner and comprises, for reprinting, steps of removing pad printed matter from the surface by removal process claimed in claim 1 and temporary pad printing on the surface thus obtained using a mixture of organic ink, colour (s), shade (s) and a hardner. Still according to another embodiment a process of temporary pad printing/reprinting on uneven surface of a glass container which according to another variant embodiment applicable to glass containers bearing temporary pad printed matter and requiring fresh matter to be pad printed thereon comprises, for printing, step of temporary pad printing using a mixture of organic ink, colour(s), shade(s) and a hardner and comprises, for reprinting, steps of removing the pad printed matter already borne on the container by removal process claimed in claim 1 and pad printing the fresh matter using a mixture of organic ink, colour(s), shade(s) and a hardner. PESCRIPT1ON OF INVENTION This invention proposes a process of pad printing using organic ink with colour(s) and shade(s) of any quality with hardener, on uneven glass surface, of a glass container removing the printed matter and temporary pad printing using organic ink with colour(s) and shade(s) of any quality and hardner. The process is repeatable. The need for invention arises when a glass container is used for packaging a certain product but is likely to be later used for packing a different product or the left-over printed glass containers bearing temporary printed matter, which instead of being discarded, are to be later used for packaging a different product after removing the matter already printed thereon and printing fresh matter pertinent to the product to be later packaged therein by temporary pad printing using organic ink and hardner . These situations demand that matter, if already printed in the surface of a glass container be removed and such removal is possible if original print is in temporary pad printing. There may also be need for printing additional matter on the surface of a glass container bearing permanent printed matter that may be printed by methods like silk screening, ACL etc. Such additional printing may become necessary as a result of promotional scheme that may be launched by an industry, or for printing additional information like flavour change, addition of a flavour etc or for incorporation of an additional nutrient or for printing price changes, or for printing a logo picture relating to an important event/festival etc For repeatability of the process, the additional printing is done in temporary pad printing using organic ink with colour(s) and shade(s) of any quality with hardener to enable the printed matter to be removed and fresh matter to be printed whenever required. For removal of temporary pad printed matter, for the purposes of reprinting fresh matter, such removal of print is carried out by preferably a five-stage process consisting of passing the glass containers through water at normal climatic room temperature, followed by passing through a mixture of hot water at temperature between normal temperature 60°C and 1-2.5% sodium hydroxide, passing through a mixture of hot water at temperature between 60-80°C and 2.5 to 7% sodium hydroxide and optionally in the presence an additive like SU, passing through a mixture of hot water between normal temperature to 60°C and 1-2.5% sodium hydroxide and finally through normal climatic room temperature, wherein preferably the water used is soft water. Whether the temperature is increasing or decreasing. Alternately any chemical which can remove the printed matter, may be used, in lieu of sodium hydroxide. The care is taken that the temperature difference between two stages does not exceed 40° to 42° C and is within the permissible limits of thermal shock resistance for glass containers to prevent cracking of glass surface. By this treatment, the matter already printed on the outer uneven surface of a glass container, by pad printing using organic ink with colours) and shade(s) of any quality with hardner, gets removed. After removal of printed matter as above, the liquid, if any, inside the container is drained out. The container is then filled with the desired product to be filled therein and the mouth of the container is tightly closed so that the product packaged in the container does not come out during tilting or turning upside down. When the outer surface of the glass container, becomes dry, temporary pad printing of the required matter is done on the outer surface of the glass container by pad printing machine, using organic ink with colour(s) and shade(s) of any quality with hardener. It is to be noted that the present invention is susceptible to modifications, changes and adaptations by those skilled in the art. Such variant embodiments incorporating the concepts and features of the present invention, are intended to be within the scope of the present invention, which is further set forth under the following claims:- WECLAIM 1. A process for temporary pad printing/reprinting on an even outer surface of a glass container wherein said temporary pad printing comprises a mixture vof known organic ink/ colours/ shades and optionally a hardner and where in said reprinting on or uneven outer surface of a glass container bearing temporary pad printed matter characterised in that steps of: (a) removing temporary pad printed matter from the outer uneven surface of the glass container by a five stage process involving a first stage of washing with water at ambient temperature, second stage of passing the containers through a mixture of hot water at temperature upto 60°C and sodium hydroxide, third stage of passing the container through a mixture of hot water at temperature between 60-80°C and sodium hydroxide, fourth stage of washing with hot water at temperature upto 60°C and fifth stage of washing the containers with water at ambient temperature, temperature gradient from one stage to another not exceeding 40 to 42°C, the concentration of sodium hydroxide during said second stage is 3-4% and concentration of sodium hydroxide during said third stage is 4-7%; (b) temporary pad printing on the outer uneven surface of the glass container with a temporary pad print, wherein the ratio between ink/colours/shades and hardner is 5: 0.01 to 2 by wt. and solvent in amount of 5 to 40%. (c) A process as claimed in claim 1 wherein said step of removal of printed matter optionally includes step of scrubbing, blowing, steaming, wiping for removal of any stubborn matter on the surface of glass container, before subjecting to five-stage removal process or after five-stage removal process. 2. A process for temporary pad printing/reprinting on an uneven outer surface of a glass container as substantially described and illustrated herein.

Documents:

150-del-2001-abstract.pdf

150-del-2001-claims.pdf

150-del-2001-correspondence-others.pdf

150-del-2001-correspondence-po.pdf

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

150-del-2001-form-1.pdf

150-del-2001-form-13.pdf

150-del-2001-form-19.pdf

150-del-2001-form-2.pdf

150-del-2001-form-3.pdf

150-del-2001-form-4.pdf

150-del-2001-form-5.pdf

150-del-2001-gpa.pdf