A METHOD FOR PRINTING ON A CONVEYOR BELT

Abstract: A printed picture is appplied onto a conveyor belt consisting of reinforcing fabric with at least one layer of polyvinyl chloride, by using as printing paint/printing ink a type which is conventional in silk screen printing and comprises pigments, binders, and solvents, and preferably the printed picture is applied by means of silk screen printing with subsequent heating for approx. 15 seconds by means of hot air at 80 DEG C, and whereafter the printed picture is cooled and optionally provided with a clear PVC varnish.

Description: A method for printing on a conveyor belt Technical field The present invention relates to a method for providing a print on a conveyor belt. In grocery stores and the like, it is common practice that the customer places the goods on a conveyor belt which transports the goods to a cashier where the goods are registrated, optionally weighed an priced, and subsequently transported further to enable the customer to put the goods in a bag.. In many cases it is desirable to provide said conveyor belt with advertisements/customer information in the form of text or pictures, in the claims designated as prints. Application of such information onto the conveyor belt should take place in a simple and expedient manner, and such that the information is securely attached to the conveyor belt and is not erased during the lifetime of the conveyor belt. State of the art From US Patent No. 4.979.591 is known a conveyor belt con¬ sisting of a thermoplastic material, such as polyvinyl chloride reinforced with a suitable fabric, which can con¬ sist of a material such as a polyester or a polyamide or any other suitable material. The information or advertise¬ ment is imprinted on the outer, exposed surface of the conveyor belt by means of a transfer printing process by appling dye and adhesive to the outer surface of the belt from a backing paper under the action of heat and pressure. In the patent it is stated that said transfer takes place at a temperature in the range 120°C-160°C and at a pressure in the range 2-6 bar during a pressing period of 10-60 sec. Subsequently, the conveyor belt is provided with a coating of transparent varnish through which the applied indicia is visible and which further serves to extend the lifetime of the indicia. From US Patent No. 5.358.094 is known another conveyor belt which can be provided with advertisements or other informa¬ tion by bringing a printed sheet with said information to cling to the belt by means of electrostatic forces, which develop naturally due to the movement of the endless con¬ veyor belt. In order to secure the leading edge, seen in the direction of movement of the conveyor belt, said leading edge can be secured by means of a suitable tape. An advantageous feature of a conveyor belt in accordance with US Patent No. 5.358.094 is that the sheets with the information can be exchanged with sheets with another type of information. From Publicly Accessible Norwegian patent application No. 950.791, it is known to provide advertisements/information on conveyor belts constructed of a reinforcing fabric and an outer layer of PVC. In the application it stated that a particular type of printing is used, permitting detailed motives, and that the printing image is secured to the conveyor belt by means of pressure and heat treatment in such a manner that the indicia is melted into the conveyor belt. Summary of the invention In accordance with the process of the present invention advertisements/information is applied on a conventionally designed conveyor belt, that is a belt consisting of a reinforcing fabric being provided with one or more layers of polyvinyl chloride. Detailed description of the invention The layer of polyvinyl chloride which is to be printed should be of a relatively soft type. As paint/printing ink is used a type commonly used for silk screen printing, which is the preferred printing method. The paint/printing ink can, of course, be applied in a different manner, for instance by means of a brush or by the use of templates or the like. Silk screen printing is a well known printing method and comprises application on a finely meshed screen of a light sensitive emulsion which cures and turns water insoluble by the influence of light, whereas the emulsion can be washed out from the parts which are not exposed to light. For instance, if the information exists in the form of a negative and the screen with the light sensitive emulsion is exposed through the negative, those parts of the emulsion which are exposed through the transparent parts of the negative will cure, and vice versa, such that after the subsequent washing out of the emulsion, the non-exposed parts of the screen will be permeable to printing paint/printing ink, so that when app¬ lied to the screen, the printing paint/printing ink will penetrate the screen and transferred into the underlying con veyor band. Surprisingly it has been found that it is possible to obtain a securely attached image by using a conventional, pigmented printing paint/printing ink known per se, for screen printing, provided that the printed belt is trans¬ ferred through a heating device in which the printed pic¬ ture is heated by means of hot air at approx. 80°C for a period of approx. 15 sec. It is not fully understood why this relatively short heat treatment period gives a printed picture well adhered to the polyvinyl chloride substrate, because at said tempera- ture no melting of the printed image into the substrate can take place. In order to give the printed image a more estetical and appealing appearance and to make the image more durable, the printed image can be provided with a coating of a conventional, clear PVC varnish. It is advantageous that the printing paint/printing ink is more diluted than what is common in screen printing. A typical printing paint/printing ink for silk screen printing can consist of: 10-30 % by weight of a binder (acryl polyvinyl resins) , 10-30 % by weight of pigments, Solvent: 30-60 % 2-etoxy etylen acetate, 1-3 % cyklohexanone. A further standard silk screen printing ink can consist of: 20-30 % acryl resins and copolymers, 5-10 % additives, 5-30 % pigments. Solvent-. 20-40 % cyk1ohexanone 20-40 % ethyl-3-etoxy-propionat. The above mentioned printing inks have a pasta-like con¬ sistence, and before being used in the present invention, they are diluted with 5-10 % by weight of a suitable thinner, such as one containing 30-60 % cyclo hexane, 10-30 % ethyl glycolate, 10-50 % ethyl-3-etoxypropionat. A person within the state of art will understand that the use of silk screen printing is a simple and convenient manner of providing multi-coloured pictures being securely attached to the underlaying polyvinyl substrate.

Claims: P a t e n t c l a i m s 1. Method for applying a printed picture onto a conveyor belt of the type being used in shops and the like, said belt comprising at least one underlying, reinforcing fabric and at least one overlaying layer of polyvinyl chloride, c h a r a c t e r i z e d i n that the printed picture is applied by using at least one printing paint/printing ink of the type being used for silk screen printing, and which contains a solvent for the printing paint/printing ink, whereafter the applied print is heated in hot air at approx. 80°C, and subsequently the printed picture is provided with a clear PVC varnish. 2. Method in accordance with claim 1, c h a r a c t e r i z e d i n that the printed picture is applied with a brush by means of a template, or prefer¬ ably by means of silk screen printing. 3. Method in accordance with the previous claims, c h a r a c t e r i z e d i n that the heating period with hot air is approx. 10 seconds. 4. Method in accordance with any of the previous claims, c h a r a c t e r i z e d i n that the conventional printing paint/printing ink is diluted with 5-10 % by weight of a suitable diluting agent.

Inventors: SVANBERG DAG, SVANBERG, DAG
Applicants: SVANBERG DAG, SVANBERG, DAG
Application year: 1997
Main classification: B41M1
IPC codes: A47F9, B41M1, B41M7, G09F19, G09F23