EP4175803A1

EP4175803A1 - Adhesive composition and method for the manufacture of white or bright-colored eco-efficient fiberboard and particle board

Info

Publication number: EP4175803A1
Application number: EP21739134.1A
Authority: EP
Inventors: Christian-Marie Bols
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-07-02
Filing date: 2021-07-02
Publication date: 2023-05-10
Also published as: BE1028461A1; BE1028461B1; WO2022003173A1

Abstract

The invention relates to an adhesive composition for agglomerating wood fibers or particles to form a light-colored panel, comprising at least one natural glue, the setting temperature of which is below 175°C. The invention also relates to the method for using this adhesive composition to produce light-colored fiberboard or particle board.

Description

Adhesive composition and process for the manufacture of eco-efficient fiber or particle boards with a glossy or white color.

The invention relates to the field of manufacturing fiber or wood particle boards, MDF panel type, having a light or even white color throughout.

The introduction in 1956 of the “dry” fiberboard manufacturing process increased the speed of production, but also reduced the volume of wastewater to be treated (Williams, 1995).

Nowadays, a fiberboard production line typically consists of 14 successive stages shown in the attached Figure 1:

1. Storage (1) of wood logs: logs can be stored in the open air or ensiled and watered.

2. Debarking (2) of wood logs: the bark is removed by a drum or rotor debarker.

3. Shredding (3) into chips: the peeled logs are cut into chips 5 to 25 mm thick.

4. Platelet storage (4): platelets are stored in silos.

5. Cleaning (5) of the pads: the pads are sorted in order to eliminate sizes less than 2 mm and greater than 50 mm. Then, they are washed with water, possibly hot.

6. Preheating (6) of the plates: preheating to 50-60 ° C is an optional step the objective of which is to soften the plates to facilitate the work of the endless screw which feeds the cooker. The addition of oxidizing or reducing chemical reagents can be carried out in order to reduce the energy consumption of the shredder, to modify the properties of the fibers, whose color and whiteness thereof by reducing agents, such as sulphites and / or oxidizing agents such as peroxides ... (Kibblewhite et al, 1980; Allison, 1980; Pynnonen et al., 2004).

7. Cooking (7) of the chips: the chips are treated for 3 to 7 minutes in a pressure cooker with 6 to 10 bars of saturated steam at temperatures of 175 to 195 ° C. The parameters of the cooking step have a significant impact on the final color of the fibers.

8. Defibration (8): the cooked plates feed a shredder under a pressure of 8 to 10 bars of saturated steam. An adjustable valve adjusts the pressure and flow of fiber at the outlet.

9. Sizing (9) in the blowline: the fibers and saturated steam pass through a pipe 80 to 120 mm in diameter towards the dryer. The speed of the fibers of the order of 100 m / s and the strong turbulence make it possible to disperse the bundles of fibers. The resin, generally a urea-formaldehyde (UF) glue and the additives (water repellents, flame retardants, dyes, catalysts, etc.) are injected in aqueous solutions and under pressure into the blowline. An important limit for the solutions to be injected is the viscosity of the liquid, generally less than 150 centipoise. In general, the dry matter present in the solution is at least 50% to limit the water supply.

10. Drying (10): firstly, the fibers pass through a flash dryer with a diameter of 1 to 3 m, sometimes a length greater than 100 m at a speed of about 30 m / s and a temperature above 200 ° C. After cycloning, the fibers are exposed to a temperature below 100 ° C., favorable to the polymerization of the resin. A second cycloning allows the fibers containing 8 to 12% moisture to be directed to the former. 11. The formation (11) of the mattress: the dry fibers pass through a sieve in order to eliminate the aggregates and form a homogeneous mattress on a conveyor belt whose speed will allow the thickness and the final density of the panel to be fixed. . The company Dieffenbacher Gmbh obtained a patent on glue and additives by spraying, just before the formation of the mattress in order to reduce the need for energy for drying, but also to avoid the pre-hardening of the glue occurring during drying (EP2213431B1).

12.Pre-pressing (12): the formed mat undergoes pre-pressing in order to reduce the amount of air between the fibers and to avoid the dislocation of the fiber mat during hot pressing.

13. Hot pressing (13): the mattress is hot pressed between 175 and 190 ° C continuously or during a cycle of 1 to 5 minutes with a pressure between 0.5 and 10.0 megapascals.

14. The panel is then allowed to cool (14) and harden.

15. Finishing (15): the panel is finally sanded, cut, and possibly adorned (melamine coating, etc.).

Although wood is intrinsically a source of emission of volatile organic compounds, it is undeniable that the use of resins, and the volatile monomers they contain, poses a serious environmental problem, but especially of human health. This is why resins without added formaldehyde, such as those based on phenols, methanodiphenyl diisocyanate, polyethylene polyamines, etc., are also problematic. In addition, the high temperatures to which these resins are subjected during the conventional production process increase the vapor pressure of these highly reactive products. Finally, the hot pressing induces the entrainment of other chemical compounds by water vapor (Wang et al, 2003).

More recently, in addition to toxicity, interest has focused on the entire life cycle of industrial production. Current resins all come from petrochemicals and have difficulty meeting the sustainability and circular economy expectations sought by our society (Netravali and Pastore, 2015). Attempts to use resins based on algae in aqueous solution (US 2019/0367787) or based on vegetable proteins (US2004 / 0062920) in the formation of wood fiber boards have so far not made it possible to '' lead to a reliable or profitable industrial process.

During the 1990s, mass-dyed MDF panels were developed and are now widely used in furnishings, children's games, decoration, fittings and construction.

In order to obtain brighter colors and in order to develop a white panel in the mass, the bleaching of fibers by chemical means, the addition of white pigment and brightening agents have been considered and patented (BASF, EP1817145B1). However, the range of colors that could be developed remains limited: light gray, vanilla, light blue ...

In fact, the compounds present in the resins, together with the high pressures and / or temperatures required on the line, and particularly during baking / defibration, drying and hot pressing, provide a significant yellow component to the color of the product. panel (Nicewicz and Kowaluk, 2015). This explains why mass-tinted white has never been marketed until now.

The present invention seeks to provide a solution to several industrial problems relating to fiber panels and OSB, MDF, LDF, HDF wood particles and other lignocellulosic composites.

Solution of the invention

A first aspect of the invention relates to an adhesive composition for agglomerating fibers or wood particles to form a clear panel, comprising at least one natural glue at low temperature.

A natural low-temperature glue is a polymer (or resin) or a mixture of polymers of natural origin, the curing temperature of which is less than 175 ° C, preferably a curing temperature of between 80 and 150 ° C, of more preferably between 90 and 140 ° C.

Preferably, the composition of the invention is a powder.

The composition of the invention also comprises at least one peroxide.

The peroxide preferably represents from 0.1 to 10% by weight of the composition, preferably from 0.5 to 5% and more preferably from 1 to 4% by weight of the composition and makes it possible to confer two properties on the composition. :

- a bleaching effect on wood fibers, and

- catalysis of the agglomeration of fibers through the formation of free radicals.

This catalysis makes it possible to reduce the pressing temperature below the 175 ° C. usually used, and at the same time to limit yellowing of the fibers.

The invention also makes it possible, by limiting the pressing temperature:

- reduce energy consumption during panel production, - reduce the emission of volatile organic compounds,

- to increase the brightness of the panels and to obtain brilliant colors or a white in the mass, and

- increase the durability of the product.

The polymers of natural origin can be of animal or plant origin. These are, for example, glues based on animal proteins (milk, feathers, fish, etc.) or vegetables (soya, corn, rapeseed, wheat, etc.), native or modified cellulose, native or modified starch. , or their mixture (grains, cake, and other agro-industrial by-products, etc.).

The composition of the invention may also comprise other glues (or crosslinkers) or additives such as, for example, pigments, dyes, flame retardants, water repellents, plasticizers, absorbing and anti-UV agents, etc.

Preferably, all the adhesives of the composition of the invention have a curing temperature of less than 175 ° C, preferably a curing temperature of between 80 and 150 ° C, more preferably between 90 and 140 ° C.

A peroxide denotes a chemical compound containing a functional group of the general formula R-O-O-R '.

For example, peroxides which can be used in the invention are hydrogen peroxide, sodium peroxide, calcium peroxide, magnesium peroxide, sodium percarbonate, dialkyl peroxides, diacyl peroxides such as sodium peroxide. benzoyl or peracetals such as TMC and other organic peroxides.

In a second aspect, the invention relates to a clear panel of fibers or agglomerated wood particles, characterized in the L * a * b * CIE 1976 color space by a lightness value L greater than 70, preferably greater than 75, more preferably greater than 80.

Preferably, the values of a * and b * are each between -20 and +20, preferably between -10 and +10, more preferably between -5 and +5.

The invention consists in adding all or part of the glues, peroxides, additives, pigments, bleaching agents, etc., in the form of a solid powder dispersed and distributed by suitable equipment. The invention therefore also relates to a method of manufacturing panels made of fibers or wood particles according to which: the composition of the invention is added to the fibers or particles at one or more places of the production line of the panels situated from the drying phase fibers or wood particles and up to the formation of the mattress.

Thus, the composition, preferably in powder form, is mixed with the fibers or wood particles during a turbulent phase, during a process similar to that described with reference to FIG. 1, with the difference that the addition of glues or adhesive substances is done between steps 10 and 11 instead of being done in step 8.

Preferably, the fibers or wood particles contain between 7% and 15% moisture when they are mixed with the adhesive composition of the invention, preferably between 8 and 14%, more preferably between 9 and 13% d 'humidity. If the fibers or particles are too wet, the steam released during the pressing of the panel, in particular, risks degrading the structure of the panel. If the humidity is too low, the composition will not adhere to the fibers or wood particles. According to the method of the invention, after the addition of the adhesive composition, the steps of pressing the mattress formed are carried out at a temperature below 175 ° C.

This low temperature is made possible by the use of natural glues with low curing temperature. This significantly reduces the energy consumption of the clear panel manufacturing process and limits yellowing of wood fibers or particles.

The incorporation of the adhesive composition according to the invention, in the form of a solid powder, is carried out for a proportion of 2 to 50% (w / w) of fibers or dry particles, and preferably of 5 to 20%.

The invention makes it possible to reduce the amount of water added to the flow of fiber after defibration, which makes it possible to reduce the amount of heat required for drying, as a corollary, the invention makes it possible to reduce the temperature of the drying gases for an equivalent fiber flow rate, the reduction is 5 to 60 ° C, and preferably 5 to 20 ° C.

The use of glue at low curing temperature makes it possible to reduce the pressing temperature to temperatures of the order of 100 to 175 ° C, and preferably from 105 to 145 ° C. This temperature reduction reduces on the one hand the emission of volatile organic compounds, and on the other hand, reduces the yellowing of the formed panels allowing the production of panels of brilliant colors or white in the mass.

The invention will be better understood with the aid of the examples below as well as the drawings in which: FIG. 1 illustrates a process according to the prior art; FIG. 2 illustrates the method according to the invention; FIG. 3 illustrates an injection system for the composition according to the invention in the form of powders; Figure 4 illustrates a variant of the position of injection of the adhesive composition in the process of the invention, and Figure 5 illustrates another variant of the position of injection of the adhesive composition in the process of the invention.

With reference to FIG. 2, the process for forming a panel of fibers or of wood particles according to the invention uses the same steps as those described with reference to FIG. 1. The sizing (step 9) is not required. however no longer takes place between defibration 8 and drying 10. Instead, a step 16 of adding the composition comprising glues and additives, here in powder form, is inserted between step 10 of drying the fibers and step 11 mattress formation. The powder composition is added in the form of a cloud at the level of the cycloning of the fibers or particles. Thus, a cloud of powders mixes with a cloud of fibers or particles under very turbulent conditions to optimize homogenization.

With reference to FIG. 2, the addition of the powder composition can be done using equipment 16 which integrates a powder storage system 21, a powder transport and metering system 22, and finally a powder blowing system 23 to incorporate them into the flow of fibers or particles suspended in the air in the production line.

This equipment 16 can be incorporated on a production line just after the drying step as illustrated in FIG. 2, at the step of forming the mattress as illustrated in FIG. 4, or, and preferably, at the outlet of the mattresses. fibers of the last cyclone of the drying as illustrated in figure 5. The invention allows, when the composition is in the form of powders, to integrate into the glue polymers, natural or not, solid pigments and / or other additives, and overcomes the limit posed by the viscosity too high for the adhesive. addition in liquid form to the blowline or to the formation of the mattress (as proposed in patent EP2213431B1).

Examples

Wood fibers from a shredder were mixed in a rotating drum with several solid powder compositions comprising a natural glue and optionally additives, before forming a mattress, then hot pressed. 40X40 cm panels with a thickness of 9 mm were formed, then tested after 48 h.

Example 1:

Composition of the mattress (% W / W, as a percentage of the weight of dry matter on the weight of dry fiber)

Glue Milk protein: 8%

Cross-linker CA1130 - Solenis: 4.4%

Pigments: titanium dioxide: 4.2%

Fiber moisture: 10.2%

Pressing cycle:

Temperature of the trays: 140 ° C.

Maximum pressure / max pressing time : 9.5 MPa / 46 seconds.

Time to reach 100 ° C at the heart of the panel: 2 min 26 sec. Tests on the finished panel:

Density (kg / m3): 942 ± 23

Bending (N / mm2): 34 ± 3.3

Humidity-24h (%): 7.79 ± 0.34 Example 2:

Composition of the mattress (% W / W, as a percentage of the weight of dry matter on the weight of dry fiber):

Glue Milk protein: 8%

Cross-linker CA1130 - Solenis: 4.4%

Fiber moisture: 10.4%

Pressing cycle:

Pressing time: 6 min 26 sec.

Temperature of the trays: 150 ° C.

Maximum pressure / max pressing time : 9, lMPa / 106 seconds.

Time to reach 100 ° C at the heart of the panel: 2 min 40 sec. Tests on the finished panel:

Density (kg / m3): 870 ± 27

Bending (N / mm2): 35 ± 5.1

Humidity-24h (%): 8.02 ± 0.56

Example 3:

Glue Milk protein: 15%

Sodium percarbonate catalyst: 0.4%

Fiber moisture: 10.1%

Pressing cycle:

Pressing time: 6 min 5 sec.

Temperature of the trays: 120 ° C.

Maximum pressure / max pressing time : 7.1 MPa / 45 sec.

Time to reach 100 ° C at the heart of the panel: 2 min 07 sec. Tests on the finished panel:

Density (kg / m3): 833 ± 14

Bending (N / mm2): 32 ± 2.8

Humidity-24h (%): 7.16 ± 0.26 Example 4:

Soy protein glue: 15%

0.6% sodium percarbonate catalyst

Linseed oil: 2%

Fiber moisture: 9.3%

Pressing cycle:

Pressing time: 7 min 30 sec.

Temperature of the trays: 105 ° C.

Maximum pressure / max pressing time : 7.2 MPa / 75 sec.

Time to reach 100 ° C at the heart of the panel: 3 min 25 sec. Tests on the finished panel:

Density (kg / m3): 1002 ± 33

Elasticity (N / mm2): 3076 ± 56

Humidity-24h (%): 7.89 ± 0.44

Swelling-24h (%): 10.88 ± 0.24

CIELAB color: L * = 75; a * = 2.6; b * = 7.5

Example 5:

Glue Milk protein: 19%

Fiber moisture: 10.2%

Pressing cycle:

Pressing time: 6 min 55 sec.

Tray temperature: 115 ° C

Maximum pressure / max pressing time : ll, 9MPa / 48 sec.

Time to reach 100 ° C at the heart of the panel: 2 min 22 sec. Tests on the finished panel:

Density (kg / m3): 1097 ± 71

Elasticity (N / mm2): 3220 ± 846

Humidity-24h (%): 10.44 ± 5.56 Example 6:

Sodium peroxide: 0.6%

Calcium peroxide: 1.6%

Titanium dioxide: 4%

Zinc dioxide: 4%

Casein glue: 7%

Fiber moisture: 13%

Pressing cycle:

Pressing time: 2 min 38 sec.

Temperature of the trays: 115 ° C.

Maximum pressure / max pressing time : ll, 9MPa / 48 sec.

Color measurement on the finished panel:

L: 81.85 a: -2.64 b: 2.07

Example 7:

Sodium peroxide: 2.3%

Potato starch: 7.2%

Methyl cellulose: 12%

Zinc dioxide: 18%

Fiber moisture: 13%

Pressing cycle

Pressing time: 2 min 38 sec.

Temperature of the trays: 105 ° C.

Maximum pressure / max pressing time : ll, 9MPa / 48 sec. Color measurement on the finished panel:

L: 70.05 a: -1.88 b: 5.48

Example 8:

Sodium peroxide: 2.3%

Potato starch: 7.2%

Zinc dioxide: 22%

Fiber moisture: 13%

Pressing cycle:

Pressing time: 1 min 05 sec.

Temperature of the trays: 105 ° C.

Maximum pressure / max pressing time : ll, 9MPa / 48 sec.

Color measurement on the finished panel:

L: 75.6 a: -1.29 b: 1.52

In summary, the invention consists in adding all or part of the glues, additives, pigments, bleaching agents, etc., preferably in the form of a solid powder dispersed and distributed by suitable equipment on a production line of the same. step of drying to that of the formation of the mat, and preferably at the exit of the fibers from the last cyclone of the drying. The equipment integrates a powder storage system, a powder transport and dosing system, and finally a powder blowing system to incorporate them into the flow of fiber suspended in the air.

The invention makes it possible to reduce the temperature of the drying gases for an equivalent fiber flow rate, the reduction is from 5 to 60 ° C., and preferably from 5 to 20 ° C. The use of glue at low curing temperature makes it possible to reduce the temperature of the press to temperatures of the order of 100 to 175 ° C, and preferably from 105 to 145 ° C. The above combined characteristics allow, on the one hand, the production of panels of brilliant colors or white in the mass.

Bibliography Williams, W. The panel pioneers: an historical perspective. Wood Based Panels International 17 (September) 6 (1995).

Kibblewhite, R.P. Brookes, Diane and Allison, R.W. Effect of ozone on the fiber characteristics of thermomechanical pulp. Tappi. 63 (4): 133 (1980).

Allison, R.W. Low Energy Pulping Through Ozone Modification. Appita J. 34 (3): 197-204 (1980). Pynnonen T., Hiltunen E., Paltakari J., Laine J.E. and Paulapuro H. Good bonding for low-energy HT-CTMP by press drying, Pulp & Paper Canada T 57105: 3 (2004).

Claims

1. Adhesive composition for bonding fibers or wood particles to form a clear panel, comprising at least one natural glue, the curing temperature of which is less than 175 ° C.

2. Composition according to claim 1, in powder form.

3. Composition according to one of claims 1 and 2, comprising at least one peroxide.

4. Composition according to claim 3, in which the peroxide represents between 0.1 and 10% by mass, preferably from 0.5 to 5% and more preferably from 1 to 4% by mass of the composition.

5. Composition according to one of claims 1 to 4, wherein the hardening temperature of the natural glue is between 80 and 150 ° C, more preferably between 90 and 140 ° C.

6. Composition according to one of claims 1 to 5, wherein the natural glue is based on natural polymers.

7. Fibreboard or chipboard, characterized in the L * a * b * CIE 1976 color space by an L lightness value greater than 70.

8. Panel according to claim 7, in which the values of a * and b * in the L * a * b * CIE 1976 color space are each between -20 and +20, preferably between -10 and +10.

9. Panel according to one of claims 7 and 8, comprising 2 to 50% by mass of the adhesive composition according to one of claims 1 to 5 relative to the mass of fibers or dry particles, and preferably from 5 to 20 % by mass.

10. Manufacturing process for fiber or wood particle boards according to which:

- The composition according to one of claims 1 to 6 is added to the fibers or particles in one or more places of the production line of the panels located from the drying of the fibers or particles of wood and until the formation of the mattress.

11. The method of claim 10, wherein the fibers or wood particles contain between 7% and 15% moisture when mixed with the adhesive composition.

12. Method according to one of claims 10 and 11, wherein the steps of pressing the formed mat are carried out at a temperature below 175 ° C.

13. Method according to one of claims 10 to 12, wherein the composition is added at the outlet of the fibers or particles of the last cyclone of the drying.

14. Method according to any one of the claims

10 to 13, in which one uses an equipment (16) integrating a storage system (21) of the powders, a system (22) for transporting and dosing the powders, and finally a blowing system (23) of the powders for the powders. incorporating into the stream (24) fibers or particles suspended in the air.

15.Process according to any one of claims 10 to 14, in which the incorporation of the powdered adhesive composition is carried out in a proportion of 2 to 50% (w / w) of dry fiber.

16.Procédé according to one of claims 10 to 15 wherein the glue used is a glue based on one or more natural polymers, of animal or plant origin such as for example animal or plant proteins, native or modified cellulose, native or modified starch, or a mixture thereof.