Case and carton sealing

Case and carton sealing is a high volume application for hot melt adhesives. Typical formulas use 20-30% wax, 25-40% polymer, and 35-55% tackifier resin. The basic requirements for packaging adhesives will be described followed by formulating guidelines for specific market areas. The focus of this discussion will be on EVA and EnBA-based systems, which are the most common. 

Hot melt adhesives based on poly(3HB-co-3HV) have also been described [119]. Hot melts are commonly used in bookbinding, bag ending and case and carton sealing and are mostly based on synthetic materials such as polyethylene, polypropylene ethylene-vinyl acetate and styrene block copolymers [119]. Hot melts based on PHAs alleviate the dependence on petroleum based materials and allow the development of biodegradable alternatives based on natural raw materials. 

Adhesives for Case and Carton Sealing. Once the corrugated board or the solid fiberboard boxes are constructed, they must be glued, filled with product, and the top flaps folded down and glued closed before shipment. The adhesive... 

Dextrins have many applications, with adhesives being their primary market (11,96). Dextrins are used as adhesives for case and carton sealing. For this application, borax is often added to the dextrin to add stability and increase viscosity. Dextrins are added to adhesives used in the laminating of products such as paperboard and shipping containers. The paper industry adds dextrins in adhesives for tube winding and bag adhesives. Library pastes, bottle label adhesives, envelop adhesives, gummed tape, and wall covering adhesives all benefit fiom dextrin addition. 

It is interesting here to compare the three techniques which are used in packaging for cases and cartons closing in large plants, as far as the available speeds, strength, costs, ease of application, ease of opening are concerned. In the past, cases were closed and sealed with staplers. This was a fairly slow and manual application, and it is less and less used, and only for small jobs, small production output. For the medium speed production lines upto 5 cases per minute, pressure sensitive tapes, applied by automatic unwinders, are suitable and used. 

Dextrins are frequently formulated with borax, sodium metaborate, boric acid, or caustic in different proportions to give good tack and higher stable viscosities at moderate concentrations. The pH of the formulations is about 9.0 in most cases. Borated dextrins find use in case sealing, carton sealing, tube winding, and laminating. 

The tops and bottoms of corrugated boxes are closed with case sealing adhesive. Although liquid glues and hot melts are preferred, carton adhesives are used, sometimes with added caustic. Carton sealing involves bonding the bottom and top flaps of folded paper boxes. A... 

Where folding cartons are to contain a product which is sensitive to moisture pickup, barriers are available which can be incorporated into the carton construction. An example of this is polyethylene laminated to paperboard. In some cases an insert bag is used instead, but this requires an additional operation and is usually accomplished by a form-fill-seal machine that makes a bag which is then inserted by another machine into the folding carton. 

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