METHOD TO ENABLE RECYCLING OF A PANEL

Abstract

The present invention pertains to a method to enable recycling of a panel comprising as a core structural component a polysaccharide fibre based plate at least one side of which is covered with a layer of a non water soluble adhesive, the method comprising immersing the panel in an aqueous liquid at least until the polysaccharide fibre based plate has absorbed an amount of liquid that leads to detachment of the adhesive from the polysaccharide fibres and at least partial detachment of neighbouring polysaccharide fibres from each other, resulting in a mixture of at least partially individualised polysaccharide fibres and separate adhesive, and thereafter removing the adhesive from the mixture.

Claims

1. A method to enable recycling of a panel comprising as a core structural component a polysaccharide fibre based plate at least one side of which is covered with a layer of a non water soluble adhesive, the method comprising immersing the panel in an aqueous liquid at least until the polysaccharide fibre based plate has absorbed an amount of liquid that leads to detachment of the adhesive from the polysaccharide fibres and at least partial detachment of neighbouring polysaccharide fibres from each other, resulting in a mixture of at least partially individualised polysaccharide fibres and separate adhesive, and thereafter removing the adhesive from the mixture.

2. A method according to claim 1, wherein the adhesive is a solid while the panel is immersed, wherein the adhesive is removed using a mechanical method such as sieving, sedimentation or centrifugation.

3. A method according to claim 1, wherein the at least one side of the plate is substantially completely covered with the layer of adhesive.

4. A method according to claim 1, wherein the panel is mechanically broken up into pieces having a volume of at most 100 cm.sup.3 before it is immersed in the aqueous liquid.

5. A method according to claim 1, wherein the panel is mechanically broken up into pieces having a volume of at most 50 cm.sup.3 before it is immersed in the aqueous liquid.

6. A method according to claim 1, wherein the adhesive is a hot melt adhesive.

7. A method according to claim 6, wherein the hot melt adhesive has a melting temperature between 80 C. and 250 C.

8. A method according to claim 6, wherein the hot melt adhesive comprises a polyester polymer.

9. A method according to claim 8, wherein the polyester polymer is a condensation polymer.

10. A method according to claim 8, wherein the polyester polymer has a weight averaged molecular weight (Mw) between 15,000 and 30,000 g/mol.

11. A method according to claim 8, wherein the polyester polymer has a crystallinity of between 5 and 40%.

12. A method according to claim 1, wherein the panel is a multilayer panel comprising multiple stacked sub-panels, wherein each sub-panel comprises as a core structural component a polysaccharide fibre based plate and in that the sub-panels are interconnected using the said non water soluble adhesive.

13. A method according to claim 12, wherein the multilayer panel is provided with a surface coating that is impervious to water.

14. A method according to claim 13, wherein the surface coating is a coating that is formed in situ on the panel using a heat curable one component powder.

15. A method according to claim 14, wherein the powder comprises a thermal initiation system comprising a peroxide, preferably an organic peroxide.

16. A method according to claim 14, wherein the powder comprises a polyester resin and a co-crosslinker chosen from the group of vinylethers, vinylesters, methacrylates, acrylates, itaconates and mixtures thereof.

17. A method according to claim 1, wherein the polysaccharide fibres are cellulosic fibres.

18. A method according to claim 17, wherein the polysaccharide fibres are of plant origin.

19. A method according to claim 1, wherein the polysaccharide fibre based plate contains less than 5% binder, preferably less than 4, 3, 2 or 1% binder up to even no binder.

Description

EXAMPLES

Example 1

[0036] A first experiment was carried out on lab scale wherein small structural plates for use in manufacturing structural panels were coated with an adhesive, in order to test separation of the plate and adhesive using the method of the invention. Three small plates (approximately 106 cm) cut out of so-called ECOR panels (ECOR FlatCOR

[0037] UA Brown, manufactured in Serbia, available via ECOR R&D Center BV, Venlo, Netherlands; polysaccharide fibre based plates from 50% old corrugated containers and 50% virgin papermaking fibre) were coated with a polyester hot melt adhesive. The first two plates were coated on one side with 150 and 170 g/m.sup.2 respectively. The third plate was coated on both sides with about 150 g/m.sup.2. All of the plates were broken up in small pieces by a household blender of 1400 Watt (Bagimex: BL10-powerblender). Of each sample, 150-200 grams of the broken material was immersed in water for 4 consecutive days. During these 4 days the water uptake was about 100% (each gram of panel absorbed about one gram of water). After this, a mixture was obtained resembling pulped paper, clearly indicative of the polysaccharide fibres being at least partially individualised. More importantly, flakes of adhesive separated from the plate material were visible in the resulting mixture. These flakes could be easily removed using a coarse screen. After removal of the adhesive, the remaining mixture was tested for the presence of adhesive by assessing potential phase separation. No such separation could be seen and a homogenous polysaccharide fibre layer was formed through sedimentation. The mixture apparently consisted (mainly) of water and polysaccharide fibres. The mixture was blended and a new plate could be formed using a Bchner funnel and subsequent pressing of the cake in a hot press at 177 C., 209 psi for 5 minutes.

Example 2

[0038] A second experiment was carried out on a larger scale. An ECOR panel of the same type as used in example 1, weighing approximately 4 kg, was coated one sided with a polyester hot melt adhesive (about 100 g/m.sup.2). The panel was sawn into strips having dimensions of about 10 cm120 cm. The strips were immersed in water overnight. After one night of immersion into water, the adhesive could be very easily separated from one of the strips. Thus, it looked like the fibres were detached form the adhesive after this one night of immersion only. To be sure of this, the remaining strips were broken up into smaller pieces (as described under example 1) and immersed again for 10, 20 or 30 minutes respectively. With increasing amount of time, more and more flakes of adhesive (having an approximate size of 1 cm.sup.2) became visible. Actually, the adhesive could almost completely be removed as a film with the same size as the panel pieces. The difference between 20 and 30 minutes was small, thus assuming that after 30 minutes almost all adhesive was separated from the panel pieces. The soaked panels were pulped during 30 minutes in an 80 litre pulper (BI-pulper) as is used for paper at 10% dry solids content. The adhesive flakes could be easily removed from the fibres using a 3 mm screen.

[0039] Microscopic analysis of the remaining mixture revealed that a small amount of tiny pieces of adhesive, having an approximate diameter of 0.3 mm were still present in the aqueous mixture. These pieces could be removed using a screen with 0.2 mm slits. About 8 kg of mixture remained (water plus about 1.6 kg of polysaccharide fibres) which was used to produce a new panel in a hot press. This panel was of a good quality, no traces of the adhesive were visible. Also, the panel did not stick to the metal screens in the press, which confirms that hardly any to no adhesive was present on the surface.

Example 3

[0040] 15 grams of Pattex D2 wood glue was applied onto an ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 18 g) in stripes and distributed into one layer with a spatula. Another ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 29 g) was put onto it. This sandwich was left to dry for 12 days at room temperature with a weight of 1600 grams on top of the sandwich. After that the sandwich was cut axially in two identical circle segments.

[0041] One half of the dry sandwich (24 g) was left in 1 l water for 10 minutes to soak completely. The ECOR platelets could be taken apart at the side and it was clear that the glue could be removed as one continuous film.

[0042] The other half was torn apart by hand. All wet material was repulped with a household blender (Bagimex: BL10-powerblender, 1400 Watt) during 20 s at intensity 4. A thick pulp of about 2.5% dry solids was obtained. White pieces of the glue film were clearly visible. These pieces could be rubbed apart between the fingers. This indicates that the remaining DIP fibers can be separated from the adhesive film particles by gentle screening.

Example 4

[0043] 9.3 grams of Bison D2 wood glue was applied onto an ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 35 g) in stripes and distributed into one layer with a spatula. Another ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 12 g) was put onto it. This sandwich was left to dry for 12 days at room temperature with a weight of 1600 grams on top of the sandwich. After that the sandwich was cut axially in two identical circle segments.

[0044] One half of the dry sandwich (28 g) was left in 1 l water for 10 minutes to soak completely. The ECOR platelets could be taken apart at the side and it was clear that the glue could be removed as one continuous film.

[0045] The other half of the sandwich was subsequently torn apart by hand. All wet material was repulped with a household blender (Bagimex: BL10-powerblender, 1400 Watt) during 20 s at intensity 4. A thick pulp of about 2.5% dry solids was obtained. White pieces of the glue film were clearly visible. These pieces could be rubbed apart between the fingers. This indicates that the DIP fibers can be separated from the adhesive film particles by gentle screening.

Example 5

[0046] 5 grams of Ivana D4 wood glue was applied onto an ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 17 g) in stripes and distributed into one layer with a spatula. In the same way 5 grams of Ivana D4 wood glue was applied to another ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 15 g). After 15 minutes drying, the two platelets were put together and left to dry for 24 hours at room temperature with a weight of 1600 grams on top of the sandwich. After that the sandwich was cut axially in two identical circle segments.

[0047] One half of the dry sandwich (18 g) was left in 1 l water for 10 minutes to soak completely. The ECOR platelets could be taken apart at the side and it was clear that the glue could be removed as one continuous film.

[0048] The other half was subsequently torn apart by hand. All wet material was repulped with a household blender (Bagimex: BL10-powerblender, 1400 Watt) during 20 s at intensity 4. A thick pulp of about 2% dry solids was obtained. White pieces of the glue film were clearly visible. These pieces could not be rubbed apart between the fingers. This indicates that the DIP fibers can be separated from the adhesive film particles by regular screening.

Example 6

[0049] 3 grams of Bison Tix gel glue was applied onto an ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 18 g) in stripes and distributed into one layer with a spatula. In the same way 3 grams of Bison Tix gel glue was applied to another ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 18 g). After about 15 minutes drying, the two platelets were put together and left to dry for 24 hours at room temperature with a weight of 1600 grams on top of the sandwich. After that the sandwich was cut axially in two identical circle segments.

[0050] One half of the dry sandwich (24 g) was left in 1 l water for 10 minutes to soak completely. The ECOR platelets could be taken apart at the side and it was clear that the glue could be removed as one continuous film.

[0051] The other half was subsequently torn apart by hand. All wet material was repulped with a household blender (Bagimex: BL10-powerblender, 1400 Watt) during 20 s at intensity 4. A thick pulp of about 2% dry solids was obtained. Yellow pieces of the glue film were clearly visible. These pieces could not be rubbed apart between the fingers. This indicates that the DIP fibers can be separated from the adhesive film particles by regular screening.

Example 7

[0052] 4 grams of Bison Polymax professional SMP polymer was applied onto an ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 18 g) in stripes and distributed into one layer with a spatula. In the same way 4 grams of Bison Polymax professional SMP polymer was applied to another ECOR 100% deinked pulp (DIP) FlatCOR platelet (12 cm; 20 g). After about 15 minutes drying, the two platelets were put together and left to dry for 24 hours at room temperature with a weight of 1600 grams on top of the sandwich. After that the sandwich was cut axially in two identical circle segments.

[0053] One half of the dry sandwich (18 g) was left in 1 l water for 10 minutes to soak completely. The ECOR platelets could be taken apart at the side and it was clear that the glue could be removed as one continuous film.

[0054] The other half was subsequently torn apart by hand. All wet material was repulped with a household blender (Bagimex: BL10-powerblender, 1400 Watt) during 20 s at intensity 4. A thick pulp of about 2% dry solids was obtained. White pieces of the glue film were clearly visible. These pieces could not be rubbed apart between the fingers. This indicates that the DIP fibers can be separated from the adhesive film particles by regular screening.

Example 8

[0055] Two ECOR FlatCOR UA Brown panels were glued to each other with a polyester hot melt adhesive and one layer of a heat cured one component powder coating was applied to it by hot pressing (150 C., Adkins ASMC 28 Heat Press). This powder coating, which is an adhesive in the sense of the present invention, was based on Uralac P 1021R and Uralac P 1910C (applied together at 240 g/m2) obtained from DSM Resins (Zwolle, The Netherlands). A piece of 64 cm (30 g) of panel was left in 1 l water for 10 minutes to soak completely. The wet panel composition could easily be torn apart by hand.

[0056] All wet material was repulped with a household blender (Bagimex: BL10-powerblender, 1400 Watt) during 20 s at intensity 4. A thick pulp of about 3% dry solids was obtained. Pure white pieces of the powder coating were clearly visible, as well as flakes of the polyester hot melt adhesive. The pieces of the powder coating were visually different from the flakes of adhesive. The powder coating pieces could not be rubbed apart between the fingers.

Example 9

[0057] An untreated MDF Panel having dimensions of 30040018 mm (lwh), weighing 1.366 kg was one sided coated with a polyester hot melt adhesive. An amount of 36 g of the molten hot melt adhesive was applied with a roller. After cooling down, the panel was immersed in water. After 48 hours the thickness of the panel increased to mm. The hot melt adhesive was released from the panel as one intact film. The remainder of the panel was pulverized in a household blender (Bagimex: BL10-powerblender, 1400 Watt).