Packaging of Dairy Products

Lesson 15 D

15.14 Semi-Rigid Containers

• The containers formed out of metal sheets / foils differ in the degree of rigidity depending upon thickness, temper, alloy and container design.

• Some are called rigid as they are not easily deformed.

• Other which are more delicate to deformation are known as semi - rigid containers. i.e. a package which is intended to maintain a definite form or shape and is not influenced by the shape or bulk of the contents but which can rather readily be bent or dented.

15.15 Set up Paperboard Boxes

• Four basic components are used to make set up paperboard boxes: paper board, adhesive, corner stays, and covering.

• Paperboard is selected to give the right weight and smoothness for the size box required.

• Sheets of the boxboard are cut and scored, the sides are folded up to make a tray, and the corner stays are adhered.

• This is repeated for the cover.

• Finally the covering material is glued on.

• Coverings may be coloured papers, foil laminates, or highly coated embossed and printed litho papers.

• Boxes can be made in almost any shape and with a wide variety of lid arrangements - separate or hinged.

• Semi - rigid plastics can be used as lids for better product display, or die cut windows can be similarly employed.

15.15.1 Advantages & disadvantages of paperboard boxes

• Convenience, individuality, strength, reusability and excellent product protection and display are the main advantages.

• Equipment required is minimum and low cost.

• Boxes are shipped set up - hence no set up time.

• Small quantities are no more expensive than large quantities making large inventories unnecessary.

Disadvantages of paperboard boxes

• Generally higher cost in comparison to folding cartons produced in large quantities.

15.16 Folding Paperboard Cartons

• A folding carton is a container made from bending - type boxboard by die-cutting and scoring it properly to fold into the desired form.

• It is supplied by the maker as a flat blank, pre-glued, or partially glued and collapsed.

• It is erected, filled and closed by the packer.

• Because they are supplied in knocked-down form (flat), folding cartons are easier to pack than set up boxes and provide economies in transportation.

• Paperboards used in folding cartons must be capable of being bent and scored.

• There are many grades and thickness ranging from cheap lined or unlined chipboards to manila, kraft, laminated and clay coated solid bleached sulfate boards. The later is best for high quality printing.

• Boards may also be coated with plastics such as polyethylene, ethylene vinyl acetate, wax or blends of resins.

• Foil laminates are used both for aesthetics and for added product protection.

• There are two common styles of folding cartons and a large number of special constructions.

• Tube types are one piece cartons that are bent into a tube (generally square) with a longitudinal glued body seam. End flaps are glued shut, tucked or self-locking.

• Tray types may be one or two piece with or without a lid. They are shipped flat and are set up and glued to form the tray and / or lid in the packager's plant. Some tray types are glued by the box manufacturer and folded flat along diagonal score lines. They can be snapped open to set up.

• Carriers for cans or bottles are special types of folding cartons.

• Cartons may be printed, embossed or die cut prior to blanking. Printing may be by letter press, offset lithography or rotogravure.

• Folding cartons are widely used for both solid and liquid foods.

• Advantages are low cost, ease of automatic high speed set up, filling and closing, good stack ability, easy opening and reclosure and excellent graphics.

15.17 Molded Pulp Containers

• When a fibrous material is mixed with water and molded, a molded pulp container results.

• These containers are made of various virgin and chemical wood pulp or wastepaper pulp. The process used closely resembles conventional papermaking techniques.

• Molded containers can be formed by pressure injection or suction molding methods.

• They are usually water sensitive but low cost.

• Uses in the food industry are for egg containers and various produce containers.