For solid and corrugated cardboard waxes like Aquaseal, Enziflex, Latyl and Paraflex are used as a surface coating and flute impregnation product. Usually they are applied by means of a two-roller system, occasionally a wire wound applicator is used.
There are three different types of cardboard, namely graphic cardboard, solid and corrugated cardboard.
During the production of graphic cardboard, medium grammage paper is glued to both sides of the base sheet. Graphic cardboard is used for e.g. book- and binder backs and puzzles, and must show excellent flatness and the ability to remain very flat. Graphic cardboard adhesives must show the following general properties:
- low/permit good bonding of medium grammage paper or board to the cardboard
- the adhesive must have a high solid content in order to ensure the lowest possible moisture absorption to maintain flatness of the cardboard
- setting speed/open time combination is completely depending upon the machine requirement and the wishes of the user
Some machines demand a high wet tack, as immediately after gluing the surfaces the cardboard makes a sharp bend, which means that the surfaces could move in relation to each other.
In case of solid cardboard, different types of paper or cardboard are glued to the base sheet (e.g. bleached kraft paper or gold foil). Solid cardboard is widely used in the packaging industry. An example is tomato boxes, for which the requirements are water resistance and flatness. Solid cardboard adhesives must fulfill the following general requirements:
- allow/permit good bonding of different paper qualities to cardboard and of the cardboard itself
- the adhesive must form a water-resistant bond: the requirements for water-resistance vary for different customers
- the adhesive must have a high solid content in order to ensure the lowest possible moisture absorption and to maintain flatness of the cardboard
- setting speed/open time is completely depending upon the machine requirement and the wishes of the user
Corrugated cardboard is produced by allowing paper to pass over preheated corrugater. The core sheet is adhered to either one or between two paper sheets. The breadth of the corrugated layer and the number of layers determines the strength of the corrugated cardboard. Corrugated cardboard is glued together by gelatinising starch.