Litho-laminating Process
The litho-laminating process is a means of creating corrugated board that has a high quality, litho printed surface. The process may use a reel or individual sheets of corrugated board as the carrier, while the top liner is normally coated paper fed from a pre-printed reel or a stack of individual printed sheets.
The litho-laminating process can be sub-divided into three main types – inline, offline, and sheet to sheet. Some litho-laminating equipment can also be used for stand-alone single-face corrugated production or sheeting.
The capabilities of any litho-laminating line will depend on the exact configuration of units included. In broad terms a line will consist of some combination of three main elements:
- Wet end: for single – face corrugated production,
- Laminating section: for adhering the printed paper to the corrugated substrate
- Delivery section
Not all litho-laminating lines feature a wet end. Each section may require additional handling and processing units which might include sheet feeders, rewinders, sheeters, tear tape applicators, and centerslit units, among others.
Process description
The key element of a litho-laminator wet end is the single facer group. This creates single face corrugated from reels of liner and fluting papers. The group is made up of several components including reel stands, splicers, pre-heaters, conditioners, and the corrugating single facer itself, often called a module facer, which creates the fluting and glues it to the liner.
The laminating section of a litho-laminator brings together the corrugated substrate, whether formed inline by a single facer, supplied on a reel, or fed as individual sheets, with the printed top paper, which may have been fed as a reel of pre-print or as individual sheets. A gluing unit applies adhesive to the flute tips of the corrugated carrier which the printed top paper is aligned with, and then adhered to. If the litho-laminate is to be delivered as sheets it will then be cut to the required length.
In the delivery section of a litho-laminator the laminated board passes through two drying stages – a single sheet compression process, where the sheets are pressed between two conveyors, and a belt press which results in good final bonding. The resulting litho-laminate is then delivered to a stacker or rewinder, depending on whether it is a web or a sheet.
Litho laminating line types
The three main types of litho-laminating lines have different capabilities, which may also vary subject to their exact configuration.
- The inline litho-laminator is predominantly used for inline sheet-to-web or web-to-web lamination, but can also be used for offline web to web laminating, double single face and sheet laminating, single face rewinding, tear tape application, and centerslit application on pre-print and unprinted webs. The line will consist of a wet end, in addition to a laminating section and delivery.
- Offline litho-laminating is mainly used for the production of sheet-to-web or web-to-web laminates, using a laminating section and delivery, but no wet end. Offline systems can also be used for double single face and sheet laminating, tear tape application, and centerslit application on pre-print and unprinted webs.
- Sheet-to-sheet litho-laminators utilize a laminating section and delivery to produce litho-laminated board from sheets of corrugated carrier and pre-printed paper.
Additionally, a litho-laminating line may be used as a standalone single face corrugator or sheeter, enabling the user to carry out single face rewinding, the production of single face reels and sheets, and the carrying out of single face center cut or centerslit on pre-print and unprinted webs.