GB1568285A

GB1568285A - Method of manufacturing surface treated boards from wood veneer or chips

Info

Publication number: GB1568285A
Application number: GB23654/77A
Authority: GB
Original assignee: Dehn Holding AS
Current assignee: Dehn Holding AS
Priority date: 1976-11-19
Filing date: 1977-06-03
Publication date: 1980-05-29
Also published as: SE7706170L; NO771858L; DK522476A; BE855342A; DE2725218A1; FR2371279A1; NL7706019A; FI771688A

Description

(54) METHOD OF MANUFACTURING SURFACE TREATED BOARDS FROM WOOD VENEER OR CHIPS (71) We, DEHN HOLDING A/S, of Box 30, 4840 Nr.-Alslev, Denmark, a Danish company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : This invention relates to a method of manufacturing surface treated boards from wood veneer or chips.

In known methods of coating of, for example, plywood boards, the coating is usu slyly applied in an operation subsequent to the manufacturing of the board itself. The preparation for such coating usually consists in polishing the surface or surfaces to be coated. This polishing on a grinding belt is necessary to smooth the surface sufficiently, in- order that the finished board may have the right surface smoothness. Besides sllioothing the surface, grinding must often be carried out to remove possible pene rations of glue, which cannot be covered by the coating. In spite of this polishing, the result is often a stained surface, which reduces the value of the finished board.In addition a substantial proportion of the outermost wooden sheet is removed in consequence of this polishing. This leads to a considerable consumption of best quality veneer, which represents the most expensive part of the board. Then follows a staining, a lacquering or a coating of the veneer with a polyester material. This coating requires special precautions for the satisfactory application and hardening of the coating mass.

Xlso the manufacture of chip boards with aye surface coating is based upon a similar coating process. In cases where the coating is of lacquer or paint, this is done in usual known manner by a preliminary polishing and deaning of the chip board, after which tlw coatings applied by spraying of lacquer or paint with a subsequent drying and har dinning. When the chip board is to be coated with a ply of veneer, for example, this can be done by applying a binding agent to the chip board, after which the veneer is-applied and the whole board exposed to pressure and heat.Instead af the veneer- a chip board can be coated with a coat of melamine by a generally known application of a melamine mixture and a woven fabric or paper.

The generally known methods of surface treatment of boards are based upon a connection or joining of a base board, which may be, for example, a hard fibre board, a chip board, plywood, or a gypsum board, with a surface coating in a subsequent operation.

According to the invention, there is provided a method of manufacturing surface treated boards from wood veneer plies - or wood chips, wherein a layer of a particulår liquid glue is spread on a lower glue-repel- lent plate of a press, glued plies or chips, glued with said particular glue, are-plåced on said layer, and before the-glue has hardened, the press is operated to compress the plies or chips and glue to produce a finished surface-treated board.

By this method it is possible to manufacture in one operation a board of wood veneer or chips which is' coated with a hardened coat of glue, which can completely replace conventional coatings. Not only the usual subsequent coating but also the pre- liminary 'surface grinding is made super- fluous, so it becomes possible to manufacture surface treated boards at a price which is considerably lower than that for conven- tionally produced boards.

The invention will be described in detail below with reference to the drawings, in which: Figure 1 shows theraw materials for manufacturing a surface treated chip board placed' in a press before compression; Figure 2 is a sectional view of the finished board made from the material of Figure 1; Figure 3 is a sectional view of the raw inaterials and the press parts on compression of the raw materials for manufacturing a lacquered chip board; and Figure 4 is a sectional view of the press with a form part.

A method of manufacturing lacquered or painted boards of wood veneer will first be described. The veneer is manufactured in the usual manner, viz. by slicing boards of wood from a log, which boards have a predetermined size. A board is chosen which is free from defects or which is of a special type of wood for use as the outermost board.

The glue is then applied to the plies in known manner. Before the glue hardens, the veneer is stacked and placed in a press, which press has a lower plate which has been made glue-repellent and then coated with glue. The stack is then compressed so that the glue is made to harden. The glue between the individual plies of veneer binds the latter together to form a board. The glue on the outside on the other hand hardens to a coating which, depending on the choice of type of glue, can meet the expected requirements of a finish coating. The impurities of the surface, which need not be removed, form part of the coating and are bound by same. Thereby the surface becomes quite smooth - and comparable to a conventional coating. When a coloured surface is wanted, a glue can be used to which have been added dyestuffs or pigments.

A suitable glue for the process is synthetic resin adhesive. A preferred glue is water based urea glue. To this glue can be added melamine to- obtain greater hardness. In using this urea glue, a coating of the board is obtained which is smooth, hard and resistant to both physical and chemical attack.

In addition to - this, the coating is noninflammable, contrary to known coatings of lacquer. Finally there is neo problem with regard to penetration of gleu through the outermost ply of wood, as any such penetration will combine with the coating which-is of the same glue material.

A method of manufacturing surface treated boards from chips will now be described. For the manufacture of chip boards, a raw material consisting of particles of lignocellulose-containing material is used. This material, which will hereafter be referred to as chips,-has usually - a length of 2-25 mm, a width of 0.5-25 mm and a thickness of 0.054.5 mm. The chips are glued i.e they are coated with glue to an extent which normally makes out a share of glue from 8-16%- on the surface and considered as dry glue on dry chips. These glued chips constitute the raw material for the manufacture of chip board.

The method of manufacturing chip boards will be explained with reference to the drawings. In Figure 1 is shown a side view of a common horizontal press for compression of the raw material 3 for a chip board 1.

The horizontal press comprises upper and lower press parts 7 and 6 respectively. The raw material is placed in correct quantity upon a non-stick plate 8, which is coated with a coat of glue 2 on the side facing the chips 3. This non-stick plate can be made for example from aluminium or steel and in a suitable manner is made glue-repellent, so that it can easily be separated from the chip board after compression. If it is wanted to manufacture a chip board with a surface coating on both sides, there must correspondingly be placed a non-stick plate above the chips. For the transportation in to the press of the raw materials on the non-stick plate 8, a base board 9, which is movable to and from the press in generally known manner is employed. When all the parts have been placed in the press they are compressed at a suitable temperature.After compression, the press parts 6, 7 are separated and the base board 9 is drawn out together with the finished chip board. Then the chip board is separated from the nonstick plate 8, and the finished surface treated chip board 1, as shown in Figure 2, has been manufactured.

A suitable non-stick plate 8 is shown in Figure 3. It consists of a ply of aluminium foil 10, which is placed upon a fine-meshed steel network 11, which is in turn placed on a laminated board 12. These plies can be conglutinated with an adhesive e.g. of polyethylene.

Finally, form parts can be used in the press, as shown in Figure 4. The form part 5 shown consists of a rib, which can be attached to the non-stick plate 8. Hereby can be manufactured chip boards which are also surface coated on their lateral faces, as the raw material forming the surface is applied to the form part 5 as well as to the non-stick plate 8. By letting the form part 5 partly extend into the-finished chip board, there can likewise be produced chip boards with weakening ribs, which make it easy to separate the boards into smaller pieces. To this is added the possibility- of producing sectional chip boards, for example for wainscots and doors.

WHAT WE CLAIM IS: 1. A method of manufacturing surface treated boards from wood veneer plies or wood chips. wherein a layer of a particular liquid glue is spread on a lower glue-repellent plate on a press, glued plies or chips, glued with said particular glue, are placed on said layer, and before the glue has hardened, the press is operated to compress the plies or chips and glue to - produce a finished surface-treated board.

2. A method as claimed in claim 1, wherein a layer of liquid glue is spread on the glued plies or chips after they have

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Figure 4 is a sectional view of the press with a form part. A method of manufacturing lacquered or painted boards of wood veneer will first be described. The veneer is manufactured in the usual manner, viz. by slicing boards of wood from a log, which boards have a predetermined size. A board is chosen which is free from defects or which is of a special type of wood for use as the outermost board. The glue is then applied to the plies in known manner. Before the glue hardens, the veneer is stacked and placed in a press, which press has a lower plate which has been made glue-repellent and then coated with glue. The stack is then compressed so that the glue is made to harden. The glue between the individual plies of veneer binds the latter together to form a board. The glue on the outside on the other hand hardens to a coating which, depending on the choice of type of glue, can meet the expected requirements of a finish coating. The impurities of the surface, which need not be removed, form part of the coating and are bound by same. Thereby the surface becomes quite smooth - and comparable to a conventional coating. When a coloured surface is wanted, a glue can be used to which have been added dyestuffs or pigments. A suitable glue for the process is synthetic resin adhesive. A preferred glue is water based urea glue. To this glue can be added melamine to- obtain greater hardness. In using this urea glue, a coating of the board is obtained which is smooth, hard and resistant to both physical and chemical attack. In addition to - this, the coating is noninflammable, contrary to known coatings of lacquer. Finally there is neo problem with regard to penetration of gleu through the outermost ply of wood, as any such penetration will combine with the coating which-is of the same glue material. A method of manufacturing surface treated boards from chips will now be described. For the manufacture of chip boards, a raw material consisting of particles of lignocellulose-containing material is used. This material, which will hereafter be referred to as chips,-has usually - a length of 2-25 mm, a width of 0.5-25 mm and a thickness of 0.054.5 mm. The chips are glued i.e they are coated with glue to an extent which normally makes out a share of glue from 8-16%- on the surface and considered as dry glue on dry chips. These glued chips constitute the raw material for the manufacture of chip board. The method of manufacturing chip boards will be explained with reference to the drawings. In Figure 1 is shown a side view of a common horizontal press for compression of the raw material 3 for a chip board 1. The horizontal press comprises upper and lower press parts 7 and 6 respectively. The raw material is placed in correct quantity upon a non-stick plate 8, which is coated with a coat of glue 2 on the side facing the chips 3. This non-stick plate can be made for example from aluminium or steel and in a suitable manner is made glue-repellent, so that it can easily be separated from the chip board after compression. If it is wanted to manufacture a chip board with a surface coating on both sides, there must correspondingly be placed a non-stick plate above the chips. For the transportation in to the press of the raw materials on the non-stick plate 8, a base board 9, which is movable to and from the press in generally known manner is employed. When all the parts have been placed in the press they are compressed at a suitable temperature.After compression, the press parts 6, 7 are separated and the base board 9 is drawn out together with the finished chip board. Then the chip board is separated from the nonstick plate 8, and the finished surface treated chip board 1, as shown in Figure 2, has been manufactured. A suitable non-stick plate 8 is shown in Figure 3. It consists of a ply of aluminium foil 10, which is placed upon a fine-meshed steel network 11, which is in turn placed on a laminated board 12. These plies can be conglutinated with an adhesive e.g. of polyethylene. Finally, form parts can be used in the press, as shown in Figure 4. The form part 5 shown consists of a rib, which can be attached to the non-stick plate 8. Hereby can be manufactured chip boards which are also surface coated on their lateral faces, as the raw material forming the surface is applied to the form part 5 as well as to the non-stick plate 8. By letting the form part 5 partly extend into the-finished chip board, there can likewise be produced chip boards with weakening ribs, which make it easy to separate the boards into smaller pieces. To this is added the possibility- of producing sectional chip boards, for example for wainscots and doors. WHAT WE CLAIM IS:

1. A method of manufacturing surface treated boards from wood veneer plies or wood chips. wherein a layer of a particular liquid glue is spread on a lower glue-repellent plate on a press, glued plies or chips, glued with said particular glue, are placed on said layer, and before the glue has hardened, the press is operated to compress the plies or chips and glue to - produce a finished surface-treated board.

been placed on the glue layer spread on the press plate and before the glue has hardened.

3. A method as claimed in claim 1 or claim 2, wherein a cover sheet of wood, plastics, fabric or paper is provided as a covering for at least one outer board surface and is coated with glue on the outside.

4. A method of manufacturing surface treated boards, substantially as herein described with reference to the accompanying drawings.

5. A surface treated board manufactured by the method claimed in any preceding claim.

6. A surface treated board substantially as herein described with reference to the accompanying drawings.