Longoni goes dry

29 August 2017


Longoni is renowned for new ideas in surface treatments and decor. Their newest technology fits the fast developing niche for in register embossing of panels, as Julian Champkin reports.

There is always something new out of Longoni. When WBPI visited the headquarters of Longoni Roberto e Figli srl in Monza last year we were shown a just-developed deep matt smear-resistant decor surface ideal not just for households which have children in them, but more seriously for public areas, shops and restaurant counters and the like. At that time, company founder Roberto Longoni spoke of another technical development which would, among other things, allow more accurate in-register embossing. At the time the company was not ready to give details of how and why it worked. Now it is.

A further year of development has happened. A pilot plant is in operation; a production partner is in place; and we can now tell almost all.

Surfacing is one of Longoni’s specialities – the technology of decor papers and the like. The standard method of adding a decor paper to a panel is to soak it in melamine resin, so that it will adhere. ‘The question we asked ourselves,” says Mr Longoni, “was: ‘Why do we impregnate liquid resin into paper?”

The answer they came up with was: For no good reason. Spread a solid powder on the paper instead.

“We spread melamine powder, 100% solid, on top of the paper,” says Mr Longoni. Then it goes to the pressing line. “Magically,” he says “the resin goes through the paper and fixes 100% onto the wood surface of the panel beneath.”

The system works for both high- and low-pressure presses, for MDF or for particleboard. The company’s pilot plant, in Cantù, north of Monza, started up in November 2016 and has been running for over six months now.

“One of the problems was in obtaining a light melamine pressing powder. Now we have one,” says Mr Longoni. “We are working with Chemisol, who will be producing it in quantity.”

The pilot plant can use papers up to two metres wide. “Then, instead of paper, we tested it on veneer. It was an unexpected use for us. Someone said ‘It might work’ – and it did. So now we can use a resin powder on top of fixed veneer to give a smooth, shiny surface, one in which the wood looks like wood but has a protective barrier.”

‘Blue sky thinking’ can produce a series of happy, if unexpected, applications. Another such comes when you use the system on decor paper, as it was originally conceived for. It follows from the fact that that the paper does not get wet, because you are not dipping it into a solution of anything. Consequently, staying dry, it does not expand or change shape. “And that makes it ideal for in-register embossing,” says Mr Longoni.

Wet paper distorts. A major problem with in-register embossing is to keep the pattern that is printed on the impregnated – i.e. wet – decor paper aligned with the pattern that is engraved into the press plates. The wet paper’s expansion can easily distort it so that the part of the image that should be raised can end up in a valley. Dry paper sidesteps that problem. “We tried it with deep embossing also. The result was good.”

So in-register embossing, which in terms of consumer demand is booming, becomes simpler and more accurate.

Another advantage of the technology is that the plant is smaller that its wet-process equivalent: the line can be 20 metres long instead of sixty or seventy. That saves not only space, but also investment cost; and it saves energy.

However, nothing in life is entirely without a down-side.

“There is a disadvantage,” says Mr Longoni. “You have to use melamine powder. Because this is a new application for melamine powder, at the moment the price is a little higher than using the old way. So we are trying to reduce the quantity of dry resin that our method uses.”

And Longoni is succeeding in that endeavour. “Now, for 60-70 grams of raw paper, we use 65-70 grams of dried resin. That is about 10% less than before. And the quality is better. The result is far more glossy, because there is no residual water trapped inside to force its way out as steam. The surface looks smoother and shinier. For matt finishes, the advantage is a shorter cycle.”

Spreading of the powder must be even. Longoni is working with the people who came up with the idea, Mr Cassaghi and Mr Nassati, who are wood technologists and inventors who also thought up the anti-smear surface that we mentioned at the start of this article. “We implement their ideas,” says Mr Longoni, “and develop them together. It is near to commercial production,”’ he adds. “We have sold all the product from our pilot plant. We have agreements with companies in Italy, and in other parts of Europe. ”

Nevertheless, Longoni is not expecting the process to replace the standard one. “Rather, we see it as a niche.” The reason is press speed.

“Our pilot plant is not very high speed.

It runs at five metres per minute. We are confident that we can reach higher speeds, of 30-40 metres a minute, for commercial production at the end of this year. Even so, that compares with mass production where speeds are 70-80 metres per minute. But for high quality, specialised, product in short runs, our process is ideal,” says Mr Longoni. And high-quality, customer-specific, short-run production is of course where an important segment of the panel industry has been heading, in Europe and in the rest of the world.

“We have some new potential clients,” says Mr Longoni. “In Thailand, we have supplied a production line; we have just completed an HPL plant in Saudi Arabia, and we are preparing a line in Pakistan. A client from Indonesia made first contact with us at Ligna. We have the niche for supplying technology and resins outside Europe. “We try to provide something different. Standard technology is supplied by many people. Italy has the technology for new things.”