Solventless Laminating Machine: Two Layers or Three

A solventless laminating machine joins two webs with an adhesive that carries no solvent, so there is no drying tunnel to run and no solvent to recover. The WRJ i9 is the two-layer version of that idea: one nip, two unwinds, one rewind, built for the structures that make up most flexible packaging. Whether it fits a plant depends less on the machine than on how many layers the pack actually needs.

WHAT THE MACHINE DOES IN ONE PASS

Two webs run into the machine. The first passes the coating unit, where a thin film of adhesive is metered onto its surface. The second is brought against it at the nip, and the pair leaves as one laminate. There is no oven between those steps, because the adhesive has nothing to evaporate. That short path is the whole design argument. Fewer stations mean less web to thread, fewer places for tension to drift, and a machine that fits into a normal production hall rather than a line of its own. The alternative is a solvent-based or water-based line, where the coating unit is followed by a drying tunnel several metres long. Choosing between processes usually comes down to the structure and the run length, and once that choice is made the rest of the line follows from it.

THE SIX NUMBERS ON THE i9

Maximum laminate speed is 450 m/min. Maximum laminate width comes in three builds: 1050, 1350 and 1650 mm. Maximum unwinding diameter is 800 mm and maximum rewinding diameter is also 800 mm. Material loading is shaftless. Reel diameter is 3 plus 6 inches, which is the shaft size the winder accepts. Those six lines are the machine. Everything else on the datasheet is either a consequence of them or a claim about how they behave in production. Before two offers are compared, it helps to know which of the six a supplier is actually quoting, and specifying a coating and laminating line is the exercise that forces the question.

WHY 800 MM ON BOTH ENDS MATTERS

Unwind and rewind at the same diameter is not symmetry for its own sake. It sets how often an operator stops. A 800 mm roll of 12 micron PET and a 800 mm roll of 60 micron PE hold very different lengths, so the two ends never run out together. The practical result is one splice per pair of rolls rather than a schedule that depends on which side finishes first. Shaftless loading is the other half of that. Rolls are moved in on a trolley and lifted without a shaft to thread, which shortens the stop. On a machine running 450 m/min, changeover time is the difference between the rated speed and the achieved one.

WHAT TWO LAYERS BUYS, AND WHAT IT GIVES UP

A two-layer design keeps the web path short and the frame compact. For the structures that dominate flexible packaging, that is enough: a printed film against a sealant film, foil against a sealant, paper against a plastic. The machine does one job and does it at speed. What it gives up is the third web. A triplex structure, where a metallised or barrier layer sits between two others, needs either two passes through a two-layer machine or a machine built for three. That is a production planning question rather than a machine fault. Where the pack needs a barrier that one coating cannot give, the answer is often a multi-ply build rather than a faster two-layer run. Multi-ply solventless work has moved a long way in the last decade, and it is the honest benchmark for what a two-layer machine is not. Triplex work has its own logic, and it is worth reading before deciding that two layers covers everything a customer will ask for.

THE WIDTH QUESTION

Three builds at 1050, 1350 and 1650 mm exist because web width follows the printing press and the bag machine, not the laminator. Buy the width that matches the press, and the machine runs full width instead of trimming. Buy wider than the press and the laminator spends its life pulling a narrow web through a wide nip, which is harmless but wasteful. Buy narrower and the slitter has to split a laminate that was already at finished width, which takes a pass and adds an edge trim nobody planned for.

THE SEVEN STRUCTURES IT RUNS

The i9 is listed for PET/PE, BOPP/CPP, BOPP/PE, PET/CPP, metallised film against plastic film, aluminium foil against plastic film, and paper against plastic film. Materials named in the same document are PET, BOPP, CPP, PE, PA, VMPET, VMCPP, aluminium foil and paper. Those seven cover the everyday work: snack and confectionery film, frozen food, daily consumer goods, and general laminated packaging. Where they do not cover the job, the answer is usually a third layer or a different process, not a different setting.

TENSION AND NIP: WHERE THE BOND IS WON

The document lists multi-stage tension control and a stable composite pressure system as the machine's core mechanical argument. That is the right place to look. Adhesive is metered in grams per square metre, and a tension swing changes the film width by a fraction of a millimetre, which changes the coat weight per square metre. Two webs also mean two tension histories. The first web has just left a coating unit; the second is coming off a roll at whatever tension the unwind holds. Multi-stage control exists to keep those two from arguing at the nip. When a laminate fails, the failure is usually traceable to that argument rather than to the adhesive itself, and lamination failures are worth diagnosing in that order. It is also where the technology gap in lamination usually sits, at the nip rather than in the chemistry.

THE OPERATOR QUESTION

The manufacturer states that the control system is simplified and that a beginner can master operation in two days. Take that as a claim about the interface, not a claim about skill. Reading a tension gauge and knowing which way to turn it are different abilities, and the second one takes longer than two days. What the simple interface does buy is a shorter handover. Fewer parameters on the screen means fewer to set wrong between shifts, and on a two-layer machine there is less to coordinate than on a triplex line. XIAOPAI pairs that with an English manual and a training session on the actual line, which is where the two-day claim either holds up or does not.

WHERE IT SITS ON A LINE

The machine runs after printing and before slitting. Printed web comes off a CI flexo printing platform, picks up its sealant layer here, and goes to the 1300 horizontal slitting machine for finished reels. Placement sounds trivial and is not: a laminator that cannot hold register on a printed web turns a good printing job into waste. The three stages XIAOPAI supplies for that chain are configured together for this reason, not ordered separately and joined later. Splice quality belongs to the same chain. A splice that arrives as a tension step shows up as a bond defect twenty metres later, and splicing and roll-change practice on coating lines exists for that reason.

WHAT TO CHECK BEFORE BUYING

A solventless laminating machine is judged by the laminate it produces, not by the options list, so the checks below are about output. Five cover most of it. Ask for the coat weight the machine holds across the full 1650 mm width, not just at the centre. Ask how the tension setpoint changes between a 12 micron and a 60 micron web. Ask what happens to the nip when one unwind reaches its core. Ask how a splice is made at 450 m/min. And ask to see an inspection record from a running line, because inspection in coating and laminating is the part that catches what the eye misses. XIAOPAI answers the first four from the machine file and the fifth from a running line, which is the only way those answers mean anything. Two more are worth adding for anyone new to the process. Where extrusion coating and adhesive lamination split is a decision that comes before the model. Treating a solventless line as a solvent line with the dryer taken out is a common first mistake. Surface treatment is the other, since treatment for flexible laminates decides whether the bond holds and whether the laminate stays clear.

WHAT XIAOPAI SUPPLIES

XIAOPAI works with SINSTAR, which builds the WRJ range in Chongqing, and supplies the i9 as an authorized distributor. Wenzhou Xiaopai Electric Power Technology Co., Ltd. holds the interface from Wenzhou: configuration against the pack structure, inspection before shipment, installation and commissioning on site, training on the actual line, and a spare-parts list with availability noted. The document set is English throughout. The full specification for the solventless laminating machine range is published, alongside the structures the machine is listed for. Read the six numbers first, then the seven structures. If the pack needs a third layer, that is a different conversation and worth having before the order rather than after.

Solventless Laminating Machine: What a Two-Layer Machine Covers