[0001] The present invention relates to a process for the production composite boards and resulting composite boards. Composite boards are widely used today and have a fixed place in every-days life. Most of the boards used are made of wood and bound by adhesives based on formaldehyde resins such as urea-formaldehyde (UF), melamine-formaldehyde (MF), melamine- urea-formaldehyde (MUF) or phenol-formaldehyde (PF), which have a certain formaldehyde emission. Due to the recent development in formaldehyde legislation formaldehyde was reclassified by European Commission, and the emission of formaldehyde in boards and furniture undergo wide discussion among scientists and legislative bodies, pushing the interest of consumers for non-formaldehyde emitting solutions. With respect to board products the emission of formaldehyde is restricted by various legal regulations. Recently in this respect there has been a resin solution based on an enzymatic crosslinked protein adhesive for several applications like foundry and wooden boards. According to the general properties of enzymes as temperature- sensitive agents, an adjusted process of pressing boards has to be established.

[0002] The present invention relates to a process of board pressing at very low temperatures. The pressing of composite board types like particle boards, panel boards, DF, OSB, plywood etc. are well known; however they are without exception manufactured by pressing the mass consisting of filler, resin and - if appropriate - additives at temperatures above 110°C in a continuous or discontinuous press.

[0003] According to the invention, a process is disclosed, wherein the pressing temperature of boards is directed to the main working temperature of enzymes used.

[0004] The problem of formaldehyde emissions has nowadays popped up again after a period of quietness. Recently Formaldehyde as a substance was re-evaluated into a higher class of health hazard which may be accompanied by more stringent occupational health measures and emission levels for the consumer products.

[0005] However there is a continuous desire to further reduce the formaldehyde emissions, or to avoid formaldehyde as such in a resin. Recently developed formaldehyde free resins have shown some disadvantages in the technical performance of the products. In order to obtain Formaldehyde free resins with good technical properties, the recent developments provided a formaldehyde free resin composition that has no formaldehyde emission from the binder, during application and curing and from the final cured product.

[0006] As a basis of the present invention, this objective has been achieved by use of enzymatic cross-linked protein matter, which can be used as a binder for wooden particles, sand and other types of fillers. Description of Related Prior Art

[0007] EP2424886 DYNEA OY discloses a patent where transaminase is used for crosslinking proteinous material as a binder for certain types of filler. The document mentions the use of this technology for sand-binding for casts and board pressing but does not depict any procedure examples for the board pressing at low temperature.

[0008] According to HOLZWERKSTOFFE UND LEI E, Dunky M., Niemz P., Springer Verlag 2002 page 122ff a temperature for pressing of particle boards at 100°C has to be maintained for water evaporation in the middle of the board during pressure maintenance phase. Multi floor press has an average press temperature of 180°C.

[0009] WO2010057787 EGGER (2010) discloses an elevated pressing temperature of 155- 205°C, wherein the temperature is typically reduced during pressing, for producing a sheet, at elevated pressure of 15-23 I Pa.

[0010] US8397456 KAINDL (2013) teaches a high temperature resistant board insulation material, wherein the pressing temperature of the panel is typically higher than 200°C, preferably between 230°C and 250°C to achieve a short pressing time.

[0011] US20140216628 KRONOTEC (2014) discloses a hot pressing device for board pressing, consisting of a temperature control device, a pressure control system, heat generator and a transfer fluid. This device is dedicated to control a heat output to the pressing device, wherein the heat is transferred from a first circuit to a second circuit with variable output. However in the patent no experimental temperature range is disclosed, it is clear that this device is used for high temperature control.

[0012] EP1615575 KRONOPLUS TECHNICAL AG (2003) discloses a pressing device for continuous production of chip on fiber boards, comprising a device for addition of additional heat in form of a vapour transfer area.

[0013] EP2451655 EGGER (2011) teaches a device for a composite board in a hot press discloses an elevated pressing temperature of at least 130°C -150°C, for producing a sheet, at elevated pressure of 15-23 MPa.

[0014] EP1412147 KRONOPLUS TECHNICAL AG (2001) discloses production of an MDF board, wherein the application of glue to the fibres is done at a temperature of lower than 100°C and the pressing at 140°C.

[0015] EP1414629 KRONOPLUS TECHNICAL AG (2002) discloses a process where the pressing of boards is maintained at temperatures below 60°C with UF and MF resins. Although the patent is silent about real pressing temperatures, it can be derived from general knowledge that pressing at those low temperatures is not leading to boards, which fulfil technical requirements. Further the patent does not disclose examples, where real boards are pressed insofar the description may only be of theoretical interest. [0016] Also, EP1414629 does not disclose any information on other adhesives more as UF and MF, especially not about protein crosslinking resins. The low temperatures depicted in the patent are only regarding gluing of flakes or fibres at below 60°C, the pressing is maintained here at 150°C. Summarily, EP1414629 cannot be taken as technology anticipating against the present invention.

[0017] A processing method for Particleboard pressing is described in EP0956936, which is commonly known as the Werzalit Process, wherein this process uses hot steam for the curing of the wood or fiber containing form mass, mixed with a heat-cured binder, which is put into the form parts and pressed and cured by steam. The Werzalit process is using heat-curing resins and does not take low temperature curing into account.

[0018] According to prior art analysis, pressure of boards is performed at higher temperatures, at least at 130-160°C. There is no prior art existing, which teaches a board pressing with enzymatic crosslinked protein matter, at temperatures below 50°C.

Detailed Description of the Invention

[0019] Boards are classified according to their type, manufacturing conditions; especially resin content varies with the type that is to be produced. Different designs and layouts exist for board manufacturing plants. The process itself can be divided into several steps. Although there are a variety of machinery producers for this industry, the basic process steps are more or less constant.

[0020] The present invention is directed to a process for the production of a composite board wherein :

a) filler is provided,

b) the filler is combined with a binder, which comprises a crosslinking enzyme and a proteinous material

c) a board is shaped, and

d) the board pressed at a pressing temperature between 25°C and 120°C, preferably between 28 and 80°C, more preferably between 30 and 60 °C.

[0021] Composite boards comprise particle boards, a panel boards, MDF( Medium Density Fibre board), OSB (Oriented Strand Board) or plywood.

THE FILLER

[0022] The usual board making process starts with providing the filler. This means the preparation of wooden chips or particles in a chipper, or fibres in a refiner. For manufacture of plywood, veneers are produced by certain types of lamination cutters. [0023] After the filler material has been produced the material and the binder are blended together in a mechanical blender, or in case of plywood, the veneers are glued with the binder and prepared for the assembly in the plywood board. The board materials are not limited to wooden materials, also organic material, comprising but not limited to straw, biological residues, or wool, cellulose etc., as well as inorganic material, comprising but not limited to sand, gypsum, ceramics, stones etc. can be used for boards or board-like products.

[0024] Concerning the present invention, the filler, of inorganic or organic nature and in the form of fibres, particles, or sheets, which amount is between 80 and 99.9 wt%, and which can be wooden chips, fibres, laminates, particles and wooden material in many other shapes and sizes.

THE BINDER

[0025] In the process according to the invention, the binder comprises a proteinous material and a crosslinking enzyme. Proteinous material is organic material that comprises proteins and/or poly peptides. With polypeptides both oligopeptides (2-20 amino acids) and polypeptides are meant (molecular weight varying from 10 kD to 180 kD).

[0026] The proteinous material used is from vegetable (including algal), animal, fungal, and/or microbial (bacteria, yeast) sources, it can be enriched by at least partially separating the proteins and/or polypeptides from other source substances like polysaccharides or is hydrolysed to give polypeptides.

[0027] Suitable crosslinking enzymes are those that are able to create covalent bonds between proteins and thus are able to crosslink proteins to form a network. The advantage of enzymes is that enzymes are reactive under relatively mild reaction conditions such as low temperature and neutral pH. Further their crosslinking activity can be controlled by adjusting the temperature, pH or ionic strength. Suitable enzymes are transferases, hydrolases, oxidoreductases, laccases and lysyl oxidases, more particularly transglutaminase [EC 2.3.2.13], sortase A [EC 3.4.22.70], tyrosinase [EC 1.14.18.1], laccase [EC 1.10.3.2], lysyl oxidase [1.4.3.13] and amine oxidase [EC 1.4.3.6]. The most preferred enzyme is transglutaminase because it readily reacts with all types of proteins, is active over a wide pH range, is relatively temperature stabile and is readily commercially available, for instance under the name ACTIVA ® ex Ajinomoto. Oxidoreductase also readily crosslinks diverse proteins.

[0028] The enzyme activity is preferably between 0.5 and 50 Units per gram of proteinous material. More preferably, the enzyme activity is between 1 and 25 Units per gram of proteinous material. Hence, the amount of enzyme can be less than 1 wt% or even less than 0.1 wt%.

Generally, the enzyme is diluted to a certain standard activity, and it will be understood that if an enzyme composition is used with high activity, less of that composition can be used and visa versa. [0029] Optionally, also one or more amino resin is present in the binder in addition to the proteinous material and the crosslinking enzyme. It is also possible to have a phenolic resin present in the binder. It is for instance possible to add one or more resins of the group UF (Urea- formaldehyde), MF (Melamine-formaldehyde) MUF (Melamine-urea-formaldehyde) PF (Phenol- formaldehyde), PUF (Phenol-urea-formaldehyde), PMF (Phenol-melamine-formaldehyde) resin and MUPF (Melamine-urea-phenol-formaldehyde) resin to the binder.

[0030] Conventional resin and hardener for boards usually react only at elevated temperatures. This means some time is available until resin and hardener react, which is needed in process steps up to the hot press. Water is mainly added in face layer where it is needed for the creation of steam from the hot press plates.

[0031] Resin loads vary mostly with the type of board that is to be produced. Other influence factors on required resin load are the used wood material, general layout of the line or chips quality.

COMBINING THE FILLER AND BINDER

[0032] After the filler material has been produced, the material and the binder are blended together in a mechanical blender, or in case of plywood, the veneers are glued with the binder and prepared for the assembly in the plywood board.

[0033] The filler is mixed with the binder until the effective binder load has been applied. It is possible to combine the filler with a blend of proteinous material and enzyme, but it is also possible to add the binder components sequentially to the filler. The enzyme can be added as a solution or in solid form .

SHAPING AND PRESSING

[0034] After combination of the filler and binder, the mixture is put in shape and subjected to a pressing step by pressing, platening, form pressing at low temperatures between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C.

[0035] Optionally water is added prior to or during the shaping step. Also further additives may be added to the water such as releasing agents and additives that improve the physical properties of the resulting board.

[0036] In a particle board producing line, the mat forming is performed in the forming station. For a good density profile of a three-layer Particleboard, exact forming is very important. The face layers are much higher in density (maximum around 900 kg/m3) than the core layer which is slightly above 600 kg/m3. For internal bond strength minimum density in core layer mainly determines the breaking load of the board. This means that steady and consistent forming is absolutely crucial for board quality. In the case shown there is a density minimum of roughly 550 kg/m3 around 9 mm inside of the board. [0037] Conventionally the core- and face layers are prepared separately. The surface particles are brought to the forming belt in two wind forming chambers. The first in the beginning of the forming area (bottom surface) and the second after the core formers in the end of the forming area (top surface). Because of the wind/gravity forming there is an additional separation of the particles with in the surface layers. Depending on the through put of the line there are one or two core forming machines. These are mechanical formers which should give a homogenous distribution of the core material.

[0038] After the forming station the mat still has poor integrity and is quite thick. Before the pre-press a mat will have up to 10 times the thickness of the final pressed board. This very much depends on the wood species used, chips geometry, target density etc. In the pre-press the mat thickness will be reduced by around 50-70%. Without pre-pressing the mat would be likely to break during transport from one conveyor belt section to another.

[0039] After the pre-press are often times spraying devices are mounted that add water and/or release agent on and below the mat. Moisture sprayed on the outer mat layers increases the heat transfer in the hot-press and can boost pressing speed. Release agents can counteract problems with sticking on the press plates / belts.

[0040] In particle board preparation several pressing systems are used : multi-opening presses, single opening presses, continuous hot presses, calendar presses, extrusion presses and the so- called Werzalit Presses. Presses are considered the main components of Particleboard lines. They have evolved a lot in the history of particleboard production. These presses are also suitable for use in the preparation of other types of boards such as panel boards, MDF( Medium Density Fibre board), OSB (Oriented Strand Board) or plywood and can be used in the process according to the invention.

[0041] Multi-opening presses: Those presses are normally used as hot plate press. These devices may also be used at low temperatures between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C. Mats are then transported by several conveyor belts into the press. The press has several press plates, but it is not necessary to heat them more than the desired heat, any heat needed can be transferred by heat transfer oil.

[0042] A multi-opening press closes with hydraulic pressure until sufficient curing of the boards is achieved and then opens again for emptying. A drawback of multi opening presses is that the mats rest inside loading cage for the time interval that is needed for filling each single mat into it. When using this type of press it may be opportune to adjust the reaction conditions to ensure that cross-linking takes place during pressing.

[0043] Single opening presses : These hot-press types were introduced mainly after the usage of multi-opening presses. These devices may also be used at low temperatures between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C. Yet very few of these presses still exist today because they were replaced by continuous presses. The layout is quite simple: The mat is cut into pieces as long as the press-length. [0044] These pieces are then moved into the single opening press that closes, compresses, and cures the board. Especially due to very high press lengths of up to 50 meters these presses allowed higher output than multi-opening presses. Press temperatures are around 25-60°C. The press may be heated up to 60°C by heat transfer oil usually.

[0045] Continuous hot presses are the most common type for particleboard production today. A continuous press consists of two steel belts that are guided in a loop above and below the pressed board. Continuous presses have lengths up to 70 m. The longer the press is, the faster the production speeds can be. The belt can be heated in several segments by thermal oil and can be opened or closed by a series of hydraulic cylinders. In a special embodiment the continuous hot press can also be used at low temperatures between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C . The use of a continuous hot press in the process according the invention has several advantages:

A rapid densification of the face layers can be ensured. Upon fast curing this creates a dense surface. This can be reached by applying a very high pressure but with out any heating being applied by the hydraulic cylinders.

After that initial densification, the distance is wider in the middle section of the continuous press. At the end of the press the distance is set to the required target thickness.

The segmented layout of this press type also makes the application of a low temperature profile possible, if needed.

[0046] An inventive detail for the low temperature pressing in continuous pressing by enzymatic driven crosslinking reactions is the absence of steam. The creation of steam can cause problems at the press exit when hot steam suddenly expands due to the sudden reduction of pressure. This steam outburst reduces the quality of the resulting board. With the process according to the invention steam outbursts can completely be avoided resulting in boards with higher quality.

[0047] There are some other hot press types that are used for special types of particleboards. These special hot presses can also be used at low temperatures between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C and thus are suitable to be used in the process according to the invention.

[0048] The calendar press is in use for the production of thin Particleboards, not thicker than 8 mm. It is a continuous press type, but instead of two steel belts the boards is pressed with one steel belt against a rotating and heated drum. The cylinders have diameters of three to five meters. The boards are wrapped around the press cylinders, which is only possible because of the low board thickness. The mat must have very good cold tack because the cohesion of the particles is stressed a lot by the wrapping.

[0049] A very special type of Particleboard production process is extrusion. This process is only feasible for manufacturing of boards for special use, not for furniture application. The process is quite similar to extrusion of thermoplasts. The extrusion press can also be used at low temperatures between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C . The mix from the blender is brought into a screw transport system that squeezes the particles mixed with the proteinous material and enzymes into a low temperature press mold at 25-60°C. The densification in the screw does not create heat, and the curing happens in the non-heated mold where an "endless" board is squeezed out.

[0050] The generated strand is cut into pieces to give boards of appropriate length. This production method is regularly used for the production of pallet blocks. Another application is the manufacturing of tubular Particleboards. These are lighter than full boards and can be used for doors. The process can be performed technically easier because the process state of the art requires heated tubes inside of the press mold, which can also be used for heat transfer, but are not necessary with the invention.

[0051] Another processing method for Particleboard pressing is described in EP0956936 (2004). The patent describes the production and pressing of Particleboards for special use in molds. Main area of application for these products is outside use, like in garden furniture, window seats or fagade elements. The method is commonly known as "Werzalit process". The press as described in EP0956936 is referred to here as the Werzalit Press. The Werzalit Press can also be used at low temperatures between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C with enzymatic crosslinking technology.

COOLING/STACKING

[0052] Conventional boards leaving a hot press are still very warm with temperatures slightly below 100°C. If those were put in a stack immediately the high temperatures would cause hydrolysis of the cured resins. For the different Formaldehyde-based resin types, the resistance against thermal degradation is worst for UF, slightly better for MUF and best for PF resins. Therefore it has become usual to cool down freshly produced Particleboards to temperatures below 60°C. In the classical process this is performed in a cooling wheel which is a very large star formed device where panels are stacked and stored for some time. The device is rotating slowly, so that each board has enough time to cool down to stack temperature.

[0053] The advantage of the process according to the present invention is that a cooling wheel is no longer necessary, because the temperature of the boards when leaving the press is inherently below 60°C.

[0054] In the classical process the finished boards are put into stacks of up to several meters in height where they are stored for some time to help even low formaldehyde containing resins to cure further. Stack temperature should not exceed 60°C because of the danger of hydrolysis of the used resins. During this period, the board moisture increases until it reaches an equilibrium condition that is depending on air temperature and relative air humidity. This is typically between 6-10% moisture content.

[0055] In the present invention, stacks are no longer necessary, because the temperature of the boards when leaving the press is inherently below 60°. FIBRE BOARD PRODUCTION

[0056] The production of fiberboards from fibers has a high similarity of the process to Particleboard production. In the following detailed process description the term DF (medium Density Fibre board) is used as synonym for all Fiberboards produced in dry-process, as usual in industry.

[0057] The typical process steps are: From the refiner the fibers are brought into the blowline where the further transport is done by steam pressure only. According to the invention, an air flow would be sufficient, which reduces the cost for the process. The blowline is a relatively thin pipe of only 8 to 20 cm inner diameter, where the whole amount of fiber is put through. Reason for the small diameter is, that a turbulent air flow must be created inside the tube in order to achieve good mixing of fiber and resin. The speed of the fibers inside the blowline may be up to 100 m/s.

[0058] The proteinous material and the enzyme can be premixed in a static mixer like in Particleboard process or in a receiver tank. In that case the mix is brought into the blowline via only a few nozzles where it is pumped in with high pressure to overcome the inward pressure of the blowline.

[0059] In the classical process, resinated fibers are blown through the blowline towards the dryer to be dried. According to the invention procedure, the temperature sensitive enzyme must either be added after the drying in a separate addition step, or an alternative resination process (e.g. dry-blending) at lower temperatures is used.

[0060] In the forming station a uniform fiber mat is created to achieve boards of consistent mechanical properties. It is necessary to move the dried fibers through a system of sifters and filters to remove any clumps that would cause density fluctuations and damages to the subsequent equipment. The fibers are then laid by mat formers on a conveyor belt.

[0061] Normal MDF boards have only one layer with only one sort of fibers. From the forming station on, the processes for MDF and Particleboard manufacture are quite similar again. Differences apply in pre-pressing stage due to the much higher densification and resulting reduction of mat thickness. The pressing temperature is between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C.

[0062] Oriented strand board (OSB) are engineered wood particle board formed by adding binder and then compressing layers of wood strands (flakes) in specific orientations. OSB may have a rough and variegated surface with the individual strips of around 2.5 x 15 cm lying unevenly across each other and comes in a variety of types and thicknesses.

[0063] Oriented strand board is manufactured in wide mats from cross-oriented layers of thin, rectangular wooden strips compressed and bonded together with proteinous material and enzyle solution. The layers are created by shredding the wood into strips, which are sifted and then oriented on a belt or wire cauls. The mat is made in a forming line, wherein the wood strips on the external layers are aligned to the panel's strength axis, while internal layers are perpendicular. [0064] The number of layers placed is determined partly by the thickness of the panel but is limited by the equipment installed at the manufacturing site. Individual layers can also vary in thickness to give different finished panel thicknesses (typically, a 15 cm layer will produce a 15 mm panel thickness).

[0065] In the classical process the mat is placed in a thermal press to compress the flakes and bond them by heat activation and curing of a resin that has been coated on the flakes. In the process according to the invention, the pressing temperature is between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C, heat activation may not be necessary. Individual panels are then cut from the mats into finished sizes.

PLYWOOD PRODUCTION

[0066] Plywood is a sheet material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured boards which includes medium- density fibreboard (MDF) and particle board (chipboard).

[0067] All plywoods bind adhesive and wood fiber sheets to form a composite material. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent across all directions. There are usually an odd number of plies, so that the sheet is balanced— this reduces warping.

[0068] Plywood production requires a good log, called a peeler, which is generally straighter and larger in diameter than one required for processing into dimensioned lumber by a sawmill The log is laid horizontally and rotated about its long axis while a long blade is pressed into it, causing a thin layer of wood to peel off. An adjustable nosebar, which may be solid or a roller, is pressed against the log during rotation, to create a "gap" for veneer to pass through between the knife and the nosebar. The nosebar assists in keeping the veneer being peeled to an accurate thickness. The sheets are then patched, graded, glued together and then in the classical process baked in a press at a temperature of at least 140 °C and at a pressure of up to 1.9 MPa to form the plywood panel.

[0069] Plywood for indoor use conventionally uses the less expensive urea-formaldehyde glue, which has limited water resistance, while outdoor and marine-grade plywood are designed to withstand rot, and use a water resistant phenol-formaldehyde glue to prevent delamination and to retain strength in high humidity. In the process according to the invention a binder comprising proteinous material and a crosslinking enzyme is used, optionally in addition with UF or PF resins as described above.

[0070] In a process according to the invention the sheets are patched, graded, and mixed with a proteinous material, combined with an enzyme solution and pressed together in a press at a temperature between 25 and 120°C, more preferably between 28 and 80°C, most preferably between 30 and 60°C and at a pressure of up to 1.9 MPa to form the plywood panel.

Description of illustrative embodiments

[0071] The following paragraphs show examples for four important wood board types - Particleboard, OSB, MDF and Plywood- in respect of low pressing procedure.

Comparative Example 1 - PB Particle Board

[0072] As comparative example a standard UF resin (emission class El) for particleboard

application was used. Particleboards were produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out in a way to simulate the industrial production process as closely as possible.

[0073] The following parameters were used :

[0074] For determining board quality the following parameters were tested according to the appropriate EN norm for P2 boards. Parameter Unit Norm Sample

A B C D

Internal bond N/mm2 >0,35 0,38 0,42

Bending strength N/mm2 ≥11 12, 1 13,0

Modulus of Elasticity I\|/mm2 > 1600 2080 2300

Surface Soundness N/mm2 > 1,1 1,2 1,4

Formaldeyhde (Perforator) mg/lOOg dry board <8 6,9 7,2

Table 1 : Board characteristics of the comparative example 1.

Inventive Example 1 - PB Particle Board

[0075] As inventive example an enzyme crosslinked protein resin according to Inventive

Example A was used. Particleboards were produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out using the following parameters:

Board Length 450 mm

Board Width 450 mm

Board Thickness 16 mm

Core layer chip content 66 %

Face layer chip content 34 %

Initial chip moisture 2%

Target density 690 kg / m3

Press plate temperature 60 °C

Core Resin Load 10% (solids per dry wood)

Face Resin Load 15% (solids per dry wood)

Core Moisture after blending 7%

Face Moisture after blending 10%

Specific press time 25 s/mm [0076] For determining board quality of the inventive samples the following parameters were tested according to the appropriate EN norm for P2 boards.

Table 2: Board characteristics of the inventive example 1.

Comparative Example 2 - OSB Oriented Strand Board

[0077] As comparative example a standard MUF resin (emission class El) for OSB application was used. OSB boards were produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out in a way to simulate the industrial production process as closely as possible.

[0078] The following parameters were used :

Board Length 600 mm

Board Width 500 mm

Board Thickness 12 mm

Core layer strand content 50 %

Face layer strand content 50 %

Initial strand moisture 2%

Target density 650 kg / m3

Press plate temperature 220 °C

Core Resin Load 7% (solids per dry wood)

Face Resin Load 7% (solids per dry wood) Core Moisture after blending 6%

Face Moisture after blending 12%

Specific press time 12 s/mm

[0079] For determining board quality of the inventive samples the following parameters were tested according to the appropriate EN norm for OSB/2 boards.

Table 3 : Board characteristics of comparative example 2.

Inventive Example 2 - OSB Oriented Strand Board

[0080] As inventive example an enzyme crosslinked protein resin according to Inventive

Example A was used. OSB boards were produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out using the following parameters:

Board Length 600 mm

Board Width 500 mm

Board Thickness 12 mm

Core layer strand content 50 %

Face layer strand content 50 %

Initial strand moisture 2%

Target density 610 kg / m3 Press plate temperature 60 °C

Core Resin Load Sample A 10% (solids per dry wood)

Face Resin Load Sample A 10% (solids per dry wood)

Core Resin Load Sample B 12% (solids per dry wood)

Face Resin Load Sample B 12% (solids per dry wood)

Core Moisture after blending 8%

Face Moisture after blending 8%

Specific press time 35 s/mm

[0081] For determining board quality of the inventive samples the following parameters were tested according to the appropriate EN norm for P2 boards.

Table 4: Board characteristics of the inventive example 2.

Comparative Example 3 - MDF Medium Density Fiberboard

[0082] As comparative example a standard UF resin (emission class El) for MDF application was used. MDF boards were produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out in a way to simulate the industrial production process as closely as possible.

Board Length 450 mm Board Width 450 mm

Board Thickness 16 mm

Target density 760 kg / m3

Press plate temperature 220 °C

Resin Load 10% (solids per dry wood)

Moisture after blending 10%

Specific press time 8 s/mm

[0083] For determining board quality of the inventive samples the following parameters were tested according to the appropriate EN norm for general purpose MDF boards used in dry surroundings.

Parameter Unit Norm Sample

A B C D

Swelling 24h % < 12 11,5 11,3

Internal bond N/mm2 ≥0,55 0,65 0,67

Bending strength N/mm2 >20 22,6 21,5

Modulus of Elasticity N/mm2 >2200 1990 2250

Formaldeyhde (Perforator) mg/lOOg dry board <8 1,5 1,6

Table 5 : Board characteristics of the comparative example 3.

Inventive Example 3 - MDF Medium Density Fiberboard

[0084] As inventive example an enzyme crosslinked protein resin according to Inventive

Example A was used. I DF boards were produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out using the following parameters:

[0085] For determining board quality of the inventive samples the following parameters were tested according to the appropriate EN norm for general purpose MDF boards used in dry surroundings. Parameter Unit Norm Sample

A B C D

Swelling 24h % < 12 16,5 11,9

Internal bond N/mm2 >0,55 0,45 0,56

Bending strength N/mm2 >20 10,6 20,7

Modulus of Elasticity N/mm2 >2200 1560 2260

Formaldeyhde (Perforator) mg/lOOg dry board <8 1,9 1,9

Table 6: Board characteristics of the inventive example 3.

Comparative Example 4 - Plywood

[0086] As comparative example a standard UF resin (emission class El) for plywood application was used, plywood boards were produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out in a way to simulate the industrial production process as closely as possible.

[0087] For determining board quality of the inventive samples the following parameters were tested according to the appropriate EN norm for class 1 plywood (for use in dry surroundings). Parameter Unit Norm Sample

A B C D

Shear strength after 24h immersion in water N/mm2 ≥1 2,0 1,8

Formaldeyhde (Gas analysis) mg/m3 <3,5 2, 1 2,3

Table 7: Board characteristics of the comparative example 4.

Inventive Example 4 - Plywood

[0088] As inventive example an enzyme crosslinked protein resin according to Inventive

Example A was used. Plywood was produced in lab-conditions and tested out for various physical properties and also for Formaldehyde emission characteristics. All tests were carried out using the following parameters:

Table 8: Board characteristics of inventive example 4. [0089] Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art.

[0090] Further modifications in addition to those described above may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.

Inventive Example A: Preparation of enzyme crosslinked protein resin.

[0091] Protein extract was produced in the following manner: Emvital E 7 (pea protein, Emsland Starke GmbH) was suspended in water and after sedimentation of the non soluble matter, the supernatant was centrifuged for further purification. The obtained clear protein solution was mixed with acetone (technical grade, 95 %) in a volume ratio of 1 : 2 (protein solution/ acetone) for precipitation of the protein. The suspension was again centrifuged to obtain the precipitated protein. This protein fraction was washed again with acetone and after sedimentation the overlaying acetone was removed. The remaining acetone was evaporated by storing the precipitated protein on a teflon foil at room temperature. After drying, the protein was ground to a fine powder and was ready to use. Then buffer solution (Tris/HCI, pH 7, 20 mM) containing 0.25 % transglutaminase was added to the protein mix just prior to the addition to the filler of Inventive examples 1-4.