-_

"PROCESS FOR THE PRODUCTION OF WATER REPELLENT FLAMEPROOF COMPOSITE WOOD BOARDS"

**********

TECHNICAL FIELD

This invention relates to a process for the production of water repellent flameproof composite wood boards . More specifically, the invention relates to a process that has important advantages over similar prior art processes in terms of specifications and quality of the composite boards made.

The advantages of the process according to the invention relate substantially to two aspects: firstly, an ecological aspect, in that it does not involve the use of chemical colours which, as is known, require large installations not only for dyeing but also for treating effluents and which have an extremely high cost in both economic and environmental terms; furthermore, it contributes to stopping, or substantially limiting, deforestation.

Moreover, the process according to the invention overcomes the drawback of prior art composites which have poor water and flame resistance properties.

This invention applies to the field of wooden board production, in particular in the sector of composite wood products to be used for flooring.

BACKGROUND ART

Composite boards are manufactured throughout the world using typically African softwoods such as ayous, okoume, fromager, eyong, ilomba and others. The

manufacturing process involves chemical treatment, gluing and cutting according to specified geometric patterns to make the boards as similar as possible to natural wood.

Once finished, composite or engineered wood, as known and accepted today, comes in the form of boards or panels having specified dimensions and properties.

In order to meet specifications for distribution, softwood products undergo numerous industrial processes, including treatments with colours and pigments, which make it possible to obtain products similar to natural wood.

The reason why softwoods are subjected to such invasive processes is that market demand requires the end products to be imitations of hardwoods. Indeed, hardwood species such as those of the rosewood, ebony and walnut families are in danger of extinction and manufacturers must resort more and more to composite boards to obtain products as near to the natural product as possible. Further, natural wood panels cannot be cut into the large sizes obtainable with composites and this can be a major drawback.

Woods can also be dyed to obtain pastel shades that are extremely rare in nature. A first drawback arising from the use of prior art techniques to make composite boards is the extensive use of chemicals which requires large installations not only for dyeing but also for treating effluents and involving an extremely high cost in both economic and environmental terms. '

What is more, these prior art composites have poor resistance to water and fire. On the other hand, safety in restaurants, hospitals, theatres and other public

places and in private homes would be greatly enhanced by the use of wood that is capable of resisting attack by fire and water.

DESCRIPTION OF THE INVENTION

This invention has for an aim to provide a process for the production of water repellent flameproof composite wood boards that can overcome or at least reduce the above mentioned drawbacks. Another aim of the invention is to provide a process for the production of water repellent flameproof composite wood boards that is simple to implement and has a low impact on the environment basically because it does not involve the use of highly dangerous colouring substances and because the natural woods used as the raw material need not be high quality.

This is accomplished by a process as defined in the main claim, for the production of composite wood boards and panelling. The dependent claims describe advantageous embodiments of the invention.

The main advantages of the invention, besides those deriving from its simplicity thanks to the use of a coating machine that can apply a coat of liquid or semi- liquid product, lie essentially in the fact that the process can provide high-quality composites similar in every way to natural wood and also having the property of being resistant to both water and fire.

In addition, composites manufactured using the process of the invention can be made to look like natural wood obtained from tree species such as fromager, teak, oak, cherry, doussie, wenge, iroko, beech, spruce, poplar and any others desired, according to current taste and

.

4

fashion trends.

The fact that a wood can resist water and fire means that safety specifications can be met in many high-risk situations and environments such as in restaurants, hospitals, theatres and other public places but also in private homes.

The composite manufactured using the process according to this invention aims to avoid all the above mentioned treatments and to prevent the deforestation resulting from growing market demand for products made of wood that is beautiful, free of defects and constant in colour.

The invention provides a cost-effective consumer product affordable by all and having desirable physical and mechanical properties.

For the process according to the invention the raw materials used to make a composite of this kind may be a low-grade material or even recycled scrap which manufacturers, at present, do not even take into consideration. The veneers used in the process according to the invention are of the standard type, for example,

0.6/ 1.0/ 1.5 mm thick, normally available on the market.

The process comprises several steps, including laying up, which involves matching up the colours of the veneers to create a harmonious repeatable stack, transferring the stack of veneers to a coating line where one face of each veneer is coated with a layer of polyurethane glue, pressing in a hydraulic press, and placing on a belt saw, normally of relatively large size, where the block is squared up and end trimmed.

The block is then placed in a hydraulic press again and a quantity of molten plastic is poured over it to form a protective coat that helps hold the ends of the

layered veneers together during the final cutting or sawing operation.

DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will become evident on reading the following description of one embodiment of the invention, given as a non- restricting example, with the help of the accompanying drawing, where Figure 1 schematically illustrates an installation that implements the process according to the invention for the production of water repellent flameproof composite wood boards.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION. With reference to the accompanying drawing, the machine, denoted in its entirety by the numeral 10, consists essentially of a modified adhesive coating machine.

The machine comprises a plurality of workstations, including a first station 11 for receiving the stacks of wooden ^■ sheets or veneers to be processed, a second station 12 for gluing the sheets, a roller transfer device 13 for conveying the stacks to a third, making-up station 14 where the sheets are made up into a single glued block, and a first hydraulic press 15.

The machine ends with an extracting device 16 equipped with rollers or with a belt for conveying the block obtained to other workstations for further processing. The machine is associated with a cutting unit 17 comprising a belt saw, and with a horizontal, hot hydraulic press 18.

Other operating units that can be associated with

_

6

the machine consist of a blanking unit 19, a hot tunnel or dryer 20 and an elevating platform 21 with which personnel can pick up and check the finished product and send it on to a packaging unit . In a first embodiment of the process, typically used to make a composite panel of water repellent, flameproof wood from oak veneers, it is possible to use veneers of the standard type, for example, 0.6/ 1.0/ 1.5 mm thick, normally available on the market. As stated above, the first step in the process is known as laying up and consists in laying the veneers over each other while at the same time matching up their colours to create a harmonious, repeatable whole of specified appearance. The stack thus made up in the first station 11, is passed on to a gluing line 12 where a predetermined quantity of polyurethane glue, for example, 150 grams/sq.m. , is spread on only one face of each veneer.

Once gluing has been completed, the stack is made up once again in the third, making-up station 14, fed into the first, hydraulic press 15 and pressed, for example at a pressure of 20 kg/sq.cm, and then fed out on a roller conveyor 16.

After a predetermined length of time, for example six hours, to allow the glue to dry, the block is ready for processing.

It is then positioned on a carriage forming part of the cutting unit 17, where a belt saw, usually large sized, squares it up and trims the ends. Lastly, the block is placed in a second, horizontal hydraulic press 18 with hot plates at a temperature of 130 ⁰ C and, while subjected to heat and pressure, molten plastic is poured over it to form a protective layer, for

example 1.7 mm thick that helps hold the ends of the sheets during the final blanking operation.

Blanking is performed at the blanking station 19 and the boards are then passed through a hot tunnel or dryer 20.

The process ends at the outfeed station 21 where personnel check the finished product for quality and package it.

The polyurethane glue used in the process according to the invention, and specifically in the coating line, is advantageously of the type marketed under the SUPRASEC ^® 2060 trade name, and consisting of a modified reactivity diphenylmethane diisocyanate prepolymer (MDI) with an NCO isocyanate value of 10-16% corrected for hydrolyzable chlorine.

This material has the property of not emitting formaldehyde gas, that is, it does not contain urea- formaldehyde adhesive, known to be harmful to human health and extremely dangerous for the environment. Hot plates are used to melt the plastic because, on cooling, hot water is produced which can be used for various purposes.

In another embodiment of the process according to the invention, for making teak composites, the initial steps remain substantially the same, that is, laying up, preparation of the stacks, for example of 50 veneers, and gluing each veneer on one face only in the gluing station 12.

Once the operation has been completed, the stack is fed into the hydraulic press and pressed, for example at a pressure of 20 kg/sq.cm.

As in the embodiment already described, after approximately six hours, the boards are ready to be

processed. In this case, the boards are planed and sanded to obtain a smooth surface.

The block is made up by alternating a smooth board with a mesh of fire class 1, recycled rubber glued together at the same workstation, in the same press.

Finally, each block is placed on the belt saw line and, after being trimmed, is cut into boards of desired thickness that look like natural teak but containing a black mesh providing anti-slip properties. This product can be used very advantageously in the construction of boats, quays, transatlantic liners, swimming pool edges or other structures in contact with water.

This composite teak, using teak and other wood species, can be made by recycling materials that cannot normally be used and has properties that are equal to or even better than those of natural teak.

The invention is described above with reference to a preferred embodiment. However, obviously the invention can be modified and adapted in several ways using technically equivalent elements and without thereby departing from the scope of the inventive concept.