BE1030248B1 - Glue for plates - Google Patents

Abstract

A board comprising cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, and an adhesive that connects these cellulosic materials together, wherein the adhesive is an adhesive based on highly branched polyamides, method of making such boards and a glue for such plates.

Description

1 BE2022/5071

Glue for plates

This invention concerns a board comprising cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, and an adhesive that connects these cellulosic materials together.

This invention also concerns a method for making such a plate and also an adhesive for such plates.

This invention relates to plates comprising cellulosic materials.

These cellulosic materials can include one or more of the following materials: wood fibers, wood chips, wood chips, wood layers, wood waste from, among other things, the recycling of chipboards/wood fiber boards, flax fibers, bamboo fibers, hemp fibers, etc. These cellulosic materials can therefore include, for example, lignocellulosic materials. are. The boards are, for example, wood fiber boards, such as MDF -Medium Density Fiberboard- and HDF -High Density

Fiberboard, other wood-based boards such as chipboard, OSB (oriented strand board), plywood boards, etc. and non-wood-based fiber boards. These plates may or may not be partially or completely formed from recycled material, such as recycled lignocellulosic material. For example, the cellulosic materials can also include recycled materials from the recycling of, for example, chipboards, wood fiber boards or panels comprising such chipboards and wood fiber boards. For example, chipboards can include particles of recycled chipboards or wood fiber boards can include particles of recycled wood fiber boards.

The most common adhesive used in producing such boards is an aminoplast polymer, produced via a polycondensation reaction from urea and formaldehyde to form a urea-formaldehyde resin (UF resin). Optionally, melamine is added and a melamine urea formaldehyde resin (MUF resin) is obtained, or melamine and phenol are added (MUPF resins: melamine urea phenol formaldehyde). The great advantages of such adhesives are their low cost - because of it

2 BE2022/5071 use of generally available and cheap raw materials in their preparation -; and their high reactivity. Such adhesives can emit formaldehyde during and after polymerization under the influence of temperature or PH change. More and more efforts are being made to limit formaldehyde emissions from panels or even reduce them to zero. Therefore, formaldehyde-free adhesives were and are being sought for producing the above-mentioned plates.

US2006/0163769 describes the use of water glass as an adhesive in the production of derived wood products that are fire resistant.

A known formaldehyde-free adhesive for use in the production of derived wood products consists of polymeric methylene diphenyl diisocyanate (pMDI).

CA2019382A1 describes a mixture of isocyanate and a sufficient amount of metal soap for use as an adhesive in derived wood products. The metal soap is used as a locking compound to prevent reaction between water and isocyanate, therefore a sufficient amount of metal soap is needed. Describes further

CA2019382A1 that water glass can also be added to the mixture of isocyanate and a sufficient amount of metal soap to form an emulsion.

An additional disadvantage of all these adhesives mentioned above is that they are based on fossil raw materials.

Bio-based adhesives for panels already exist, but the production of panels using these adhesives is less simple. Disadvantages include too low reactivity, rapid prepolymerization, limited adhesive power, poor wetting properties, compared to current aminoplast adhesives containing formaldehyde. Examples of bio-based adhesives are adhesives based on lignin, plant flour such as soy, or sugars.

3 BE2022/5071

The present invention primarily contemplates an alternative sheet comprising cellulosic materials and an adhesive and a method for forming such alternative sheets, providing, according to various embodiments, solutions to the problems with such prior art sheets.

The invention concerns a board comprising cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, and an adhesive that connects these cellulosic materials, wherein the adhesive is an adhesive based on highly branched polyamides. These cellulosic materials are preferably lignocellulosic materials. The vegetable fibers are, for example, wood fibers.

These wood fibers may or may not be present in the form of wood fiber bundles.

Surprisingly, it was found that adhesives based on highly branched polyamides are useful for bonding cellulosic materials such as vegetable fibers, for example wood fibers and flax fibers, wood-containing parts, such as wood chips, wood chips, and wood layers, and recycled wood-containing parts and that, in addition, this glue provides particularly good adhesive strength. Moreover, the production of plates using this glue can be done in a similar way to the production of such plates with conventional urea formaldehyde glues (UF glues). One can therefore switch to an adhesive based on highly branched polyamides without significantly changing the production process. These plates are obtained, for example, by providing the cellulosic materials with the glue and then pressing the cellulosic materials provided with glue into plate-shaped material, whereby this plate-shaped material is, for example, sawn into plates or already forms a plate with the desired dimensions. Pressing preferably takes place at an elevated temperature, where temperatures can reach more than 200°C.

Even more surprisingly, it was found that boards comprising cellulosic materials bonded together with an adhesive based on highly branched polyamides exhibit better technical characteristics than such boards comprising conventional UF adhesives. This allows higher stiffness (N/mm?) and transverse tensile strength (N/mm?) and/or higher water resistance.

4 BE2022/5071

An adhesive based on highly branched polyamides refers to an adhesive whose dry substance largely consists of highly branched polyamides, for example of at least 50% by weight of highly branched polyamides on the total weight of the dry substance, preferably at least 70% by weight and even more. preferably at least 80 percent by weight.

Highly branched polyamides are highly branched three-dimensional macromolecules. High/strong branching indicates that the polyamides are not linear and also indicates that there are a significant number of branches. This means that there are more than 3, preferably more than 5 and even more preferably more than 10 branches present in the polyamide macromolecule.

Such polyamides can be bio-based. An adhesive comprising highly branched polyamides can, for example, be based on polycondensed amino acids, whereby these amino acids are produced, for example, with the help of bacteria.

Bacteria, such as Corynebacterium (gram positive) or Escherichia coli (gram negative), can chemically convert amino acids via fermentation into, for example, mainly lysine and some glutamine. Such adhesives therefore contribute to the durability of the panels mentioned. In addition, this glue does not have to contain formaldehyde and preferably does not contain formaldehyde, so that there is no problem with any formaldehyde emissions. When the highly branched polyamides are based on polycondensed amino acids, it is not necessary that they are based only on one type of amino acid. For example, when using bacteria that mainly produce lysine and a small portion of other amino acids such as glutamine, both lysine and glutamine can be used for the production of the highly branched polyamides, making an additional purification step of the amino acids unnecessary and the production of these adhesives can take place in an ecological manner.

An additional advantage is that plates containing glue based on highly branched polyamides can be recycled and serve as raw material to form such plates again.

Preferably, only one first type of adhesive is used to form the plates, namely adhesives based on highly branched polyamides, but the plates can also comprise other types of adhesives. For example, use can be made of an adhesive mixture comprising the first type of adhesive and one or more other types of adhesives, 5 and/or the plate can be multi-layered, whereby the first type of adhesive is used for one layer and a different type of adhesive is used for another layer. type of glue is used.

Examples of other adhesives include conventional UF adhesives, MUF adhesives, MUPF adhesives, pMDI adhesives, polyurethane adhesives, polyvinyl butyral adhesives, polyacrylate adhesives, etc. Polyurethane adhesives can, for example, be used to increase water resistance and/or flexibility. It is also possible for a plate to be formed with different glues from the first type of glue. For example, the plate can be multi-layered, with different adhesives, but for example all adhesives based on highly branched polyamides, being used for the different layers. These latter different adhesives can differ in all kinds of areas. Below is a non-exhaustive list of possible differences, whereby these differences can be combined with each other as long as this is not contradictory: dry matter content, the average molecular weight of the highly branched polyamides, auxiliary substances such as solvents, auxiliary substances such as potassium or sodium hydroxide, cross-linkers, catalysts , chemical composition of the polyamides, etc. The glue used to form the plates can include several components. All components of the adhesive can already be pre-mixed and stored that way. However, prior to forming the panels, it is not necessary that all components of the adhesive have already been mixed and stored. It is therefore possible that the components are only combined prior to gluing and/or during gluing to form the panel. The formed plate then contains the glue based on highly branched polyamides. It is not necessary that all components of the adhesive used to form the panel can be found in the panel. Certain components of the adhesive used may have reacted with each other in such a way that they are no longer (separately) visible in the panel. For example, the adhesive used can be one-piece, with all components already assembled and stored together. The glue used can also be two-part or multi-part. For example, the glue used can comprise a first part and a second part, with these two parts only preceding

6 BE2022/5071 when gluing the cellulosic materials together, or where these two parts are added separately to the cellulosic materials, whether or not simultaneously, in order to arrive at a panel comprising the aforementioned glue based on highly branched polyamides .

In a preferred embodiment, the said highly branched polyamides are obtained by polycondensation of amino acids, wherein these amino acids are preferably selected from the group containing arginine, glutamine, asparagine and lysine. The highly branched polyamides are obtained here via peptide bonds, with no preference given to functional groups of the amino acids. This results in a complex network of polyamides that can serve well as an adhesive for cellulosic materials. The highly branched polyamides are obtained, for example, from the polycondensation of mainly lysine. Lysine is a basic amino acid that is cationic in a neutral medium. Lysine is, for example, obtained via fermentation using bacteria, such as Corynebacterium or Escherichia coli bacteria. During the production of lysine, smaller amounts of other amino acids such as glutamine can also be formed. By choosing the bacteria, nutrients and fermentation conditions, the desired amino acids can be specifically formed. Multiple carbohydrate sources can be used for this fermentation, such as sucrose, glucose, cellulose, hemicellulose or lignin. Mixtures of ammonium salts, such as ammonium sulphate or diammonium phosphate, are often used as an ammonium source for fermentation. Ammonium sulphate can be obtained as a by-product during manure processing or after stripping ammonia-containing gases. In other words, the production of amino acids, such as lysine, can be completely or largely based on bio-based raw materials and/or waste materials.

In a specific embodiment, the highly branched polyamides comprise a first group of highly branched polyamides with a molecular weight between 500 and 100,000 g/mol, preferably between 5000 and 50,000 g/mol and even more preferably between 10,000 and 25,000 g/mol. mol, with the first group of highly branched polyamides preferably at least 60% by weight, even more preferably at least

7 BE2022/5071 65 percent by weight, even more preferably at least 70 percent by weight, even more preferably at least 75 percent by weight and most preferably at least 80 percent by weight of the highly branched polyamides. The reactivity of the hyperbranched polyamides is optimal if the molecular weight is higher than 5000 g/mol and the gluing can be done very well when the molecular weight is lower than 50000 g/mol. This also allows good production of the plates.

In a preferred embodiment, the plate comprises one or more layers, wherein at least one said layer comprises said cellulosic materials and said glue, whereby preferably in this layer the weight ratio of highly branched polyamides to cellulosic materials is between 0.03 and 0.15. . At this weight ratio, the cellulosic materials are preferably dried cellulosic materials. Here, only 1 layer, or only a number of layers, can comprise cellulosic materials and a mentioned glue based on highly branched polyamides, while other layers then comprise, for example, a different glue.

Preferably, all mentioned layers comprise cellulosic materials and an adhesive based on highly branched polyamides. This weight ratio is, for example, roughly calculated as the percentage of dry matter of glue on dry matter of cellulosic materials, for example on dry wood containing no residual moisture.

In a specific embodiment, the plate comprises three or more layers, being two outermost covering layers, and one or more central layers, wherein at least one central layer comprises said cellulosic materials and said adhesive, and wherein the covering layers each comprise cellulosic materials and an adhesive on based on highly branched polyamides, whereby the weight ratio of highly branched polyamides to cellulosic materials in the covering layers is higher than the weight ratio of highly branched polyamides to cellulosic materials in the latter central layer. For example, the weight ratio of highly branched polyamides to cellulosic materials in the covering layers can be between 0.06 and 0.12 and the weight ratio of highly branched polyamides to cellulosic materials in a mentioned central layer can be between 0.03 and 0.10. preferably between 0.035 and 0.05. The glue used for the coatings can be the same glue as the glue used for

8 BE2022/5071 the one or more central layers mentioned. However, it is possible that different adhesives are used for the different layers, but for example always adhesives based on highly branched polyamides. The board can, for example, be a 3-layer chipboard comprising two outer covering layers with less coarse wood chips and a central layer with coarser wood chips, wherein the outer covering layers comprise 8% by weight highly branched polyamides on dry wood chips and the central layer 4.5% by weight highly branched polyamides. on dry wood chips. Dry wood chips here refer to wood chips without residual moisture. The central layer may include recycled wood chips. Such chipboards can be manufactured using, for example, press plates at temperatures between 170°C and 245°C, at a pressure between 2 and 5 N/mm? and this for at least 3 seconds, preferably at least 5 seconds, per mm of sheet thickness. The composition of the cellulosic materials can differ per layer. The one or more central layers and/or the covering layers can, for example, comprise recycled cellulosic materials.

In a special embodiment, the highly branched polyamides comprise a first group of highly branched polyamides and a second group of highly branched polyamides, wherein the average molecular weight of the first group of highly branched polyamides is at least 3 times higher, preferably at least 5 times higher than the average. molecular weight of the second group of highly branched polyamides and/or wherein the average molecular weight of the first group of highly branched polyamides is at most 15 times higher, preferably at most 10 times higher, than the average molecular weight of the second group of highly branched polyamides. The first group of highly branched polyamides form the high molecular weight highly branched polyamides and the second group of highly branched polyamides form the low molecular weight highly branched polyamides. The combination of high molecular weight highly branched polyamides and low molecular weight highly branched polyamides improves the performance of the adhesive, in terms of both reactivity and technical characteristics. The mentioned high molecular weight highly branched polyamides, for example, have an average molecular weight of at least 5000 and preferably at least 10000 g/mol, for example an average molecular weight between 5000 and 50000 g/mol, preferably between 10000 and 25000 g/mol. The low molecular weight polyamides, for example, have a

9 BE2022/5071 average molecular weight between 500 and 5000 g/mol. With the help of this combination, the further polymerization of the adhesive during pressing of the plate is accelerated. We are talking here about groups of highly branched polyamides with an average molecular weight. Not all macromolecules from the same group have the same molecular weight. This is, for example, the result of the production of these highly branched polyamides. In the polycondensation of amino acids, not all amino acids will obtain the same reactions, i.e. the same branches, resulting in the obtained highly branched polyamides having different molecular weights. The highly branched polyamides from the same group are obtained, for example, by the same production, where, for example, for the first group of highly branched polyamides the polycondensation takes place for a longer time than for the second group of highly branched polyamides, such that the average molecular weight of the first group highly branched polyamides is higher than the average molecular weight of the second group of highly branched polyamides.

Furthermore, preferably the second group of highly branched polyamides comprises between 5 and 30 weight percent of the total weight of the highly branched polyamides, preferably between 10 and 20 weight percent.

In a preferred embodiment, the adhesive comprises crosslinkers, whereby preferably these crosslinkers are selected from the group comprising polyketones, polyesters, isocyanate dispersions, epoxides, glyoxal and other dialdehydes.

The crosslinkers mentioned are or include, for example, polyesters, whereby these polyesters are preferably dispersed and/or unsaturated polyesters. For example, these unsaturated polyesters are highly branched, making them easily soluble and not adversely affecting the viscosity of the glue used to form the plates. During the production of the plates, where pressing is used, the acidity of the polyesters is preferably brought or stabilized towards the acidity of the polyamides, so that no acid/base reactions or prepolymerization take place prior to pressing.

10 BE2022/5071

The adhesive may comprise one or more types of crosslinkers. During the pressing of the plates, these crosslinkers ensure better and faster bonding between the cellulosic materials, so that the resulting plate has the necessary strength and strength and the connection between the cellulosic materials does not break unintentionally.

In addition, with the help of these crosslinkers, the pressing time can be further shortened and the technical characteristics of the end product, such as chipboard, OSB or

MDF. The technical characteristics include bending strength, tensile strength, compressive strength and water resistance.

The crosslinkers mentioned are or include, for example, epoxides. Excellent results are achieved using epoxides, such as di-epoxides. These epoxides can, for example, be produced via bio-based routes from lignin or aniline, such as glycerol diglycedyl ether, and/or ethylene glycol diglycedyl ether. Epoxides are known to react with amines. However, it is exceptional that epoxides can be added to highly branched polyamides without prepolymerization during gluing of the cellulosic material and prior to pressing the sheet. The epoxide only becomes active when pressure and temperature are added in the press.

This does not make pressing the plate difficult and the bond between the cellulosic materials can be achieved very well. These crosslinkers can already be pre-mixed with the highly branched polyamide components of the adhesive used and stored that way. However, the crosslinkers can also be combined with the highly branched polyamide components of the adhesive used shortly before gluing. The glue used is then, for example, two-part, comprising a first part comprising the highly branched polyamides and a second part comprising cross-linkers, whereby these two parts are only joined before gluing or during gluing of the cellulosic materials. The crosslinkers mentioned can also be regarded as separate ingredients, regardless of the glue used in the production of plates, where the glue used, together with the crosslinkers, forms the glue present in the plate based on highly branched polyamides.

Furthermore, preferably the weight ratio of crosslinkers on the highly branched polyamides is between 0.02 and 0.15. For example, there can be between 3 and 6

11 BE2022/5071 weight percent epoxides are present on highly branched polyamides. A higher proportion of crosslinkers contributes to the water resistance of the glue and therefore of the plate containing this glue. The content of the crosslinkers should also not be too high, as this can cause prepolymerization of the adhesive prior to pressing the plate. This weight ratio ensures optimal technical characteristics, in particular better tensile strength, bending strength and compressive strength and better water resistance. Such panels are therefore not only suitable for applications in dry indoor conditions (service class 1), but also extremely suitable in more humid areas, such as humid indoor areas such as bathrooms (service class 2).

This invention also concerns a method for forming plates comprising cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, wherein cellulosic materials are provided and a glue is applied to these cellulosic materials, after which these glued cellulosic materials are pressed. are formed into a plate-shaped material for forming plates in this way, wherein the glue is an glue based on highly branched polyamides.

Using this method, a plate is obtained as described above.

All advantages and embodiments described above also apply to this method. Surprisingly enough, pressing into plates can be done in a similar way to pressing glued cellulosic materials into plates, where the glue is a conventional UF glue.

The cellulosic materials, such as wood chips, wood chips, wood layers, wood fibers or other vegetable fibers, are provided with glue, i.e. glued, by, for example, spraying/pouring glue onto these cellulosic materials. The cellulosic materials can be on a vibrating conveyor belt or in a mixing vessel in order to glue the cellulosic materials as homogeneously as possible. The glued cellulosic materials are then pressed together in, for example, a continuous press or a discontinuous press, under a certain pressure, for example a pressure between 2 and 6 N/mm', preferably between 2 and 4 N/mm', at a certain temperature, for example a temperature

12 BE2022/5071 between 160°C and 245°C, preferably 200°C and 245°C, and for a certain time, for example at least 4 seconds per mm sheet thickness. The glue will bond here with the cellulosic materials to obtain a sturdy panel. This adhesive can be one-part, where the adhesive is kept in its entirety and applied in its entirety to the cellulosic materials. The adhesive can also be two-part or multi-part, where the adhesive comprises two or more different parts that are kept separately, where these parts are joined together prior to gluing and thus applied as one whole to the cellulosic materials, or where these parts are joined without prior joining. are applied to the cellulosic materials, either simultaneously or separately.

Preferably, the highly branched polyamides of the adhesive are obtained by polycondensation of amino acids, whereby these amino acids are preferably selected from the group containing arginine, glutamine, asparagine and lysine.

In a preferred embodiment, the highly branched polyamides comprise a first group of highly branched polyamides with a molecular weight between 500 and 100,000 g/mol, preferably between 5000 and 50,000 g/mol and even more preferably between 10,000 and 25,000 g/mol. mol, and wherein, preferably, the highly branched polyamides comprise a second group of highly branched polyamides, wherein the average molecular weight of the first group of highly branched polyamides is at least 3 times higher, preferably at least 5 times higher than the average molecular weight of the second group of highly branched polyamides and/or wherein the average molecular weight of the first group of highly branched polyamides is at most 15 times higher, preferably at most 10 times higher, than the average molecular weight of the second group of highly branched polyamides and wherein furthermore preferably, the second group of highly branched polyamides constitutes between 5 and 30 weight percent of the total weight of the highly branched polyamides, preferably between 10 and 20 weight percent.

In a specific embodiment the plate comprises one or more layers, wherein these layers are pressed together if there are multiple layers, and wherein at least one

13 BE2022/5071 said layer comprises said cellulosic materials and said glue, wherein in this layer the weight ratio of highly branched polyamides to cellulosic materials is preferably between 0.03 and 0.15, and where in a specific embodiment the plate consists of three or more layers comprising outermost covering layers, and one or more central layers, wherein at least one central layer comprises the said cellulosic materials and the said adhesive, and wherein the covering layers each comprise cellulosic materials and an adhesive based on highly branched polyamides, wherein the weight ratio of highly branched polyamides to cellulosic materials in the covering layers is higher than the weight ratio of highly branched polyamides to cellulosic materials in the latter central layer. The adhesives for the mentioned covering layers and central layer can all be the same or they can also be different, but always based on highly branched polyamides.

In a specific embodiment, the adhesive comprises crosslinkers and/or crosslinkers are applied to the cellulosic materials, whereby preferably these crosslinkers are selected from the group comprising polyketones, polyesters, isocyanate dispersions, epoxides, glyoxal and other dialdehydes and whereby also preferably the weight ratio of crosslinkers on the highly branched polyamides is between 0.02 and 0.15. If the adhesive itself does not contain the crosslinkers, the application of crosslinkers to the cellulosic materials can take place after gluing or during gluing. For example, the crosslinkers can be mixed with the adhesive prior to gluing the cellulosic materials. Preferably, pressing takes place after the crosslinkers have been applied to the cellulosic materials. With the help of crosslinkers, polymerization is accelerated during pressing and the cellulosic materials are therefore connected more quickly. The pressing time can therefore be less than 10 seconds per mm sheet thickness. These crosslinkers may or may not be part of the adhesive. For example, the glue can be a one-part glue, where all components of the glue have already been added together and the glue is thus preserved. The glue can also be a two- or multi-part glue, wherein the glue comprises two or more parts that are joined together prior to gluing, or are applied together or successively to the cellulosic materials. For example, the glue can comprise a part with the crosslinkers and a part with the highly branched polyamides.

14 BE2022/5071

This prevents the crosslinkers from reacting with the highly branched polyamides prior to pressing the plate. The crosslinkers can also be regarded as separate components that are not part of the adhesive. The crosslinkers are or include, for example, polyesters, whereby these polyesters are preferably dispersed and/or unsaturated polyesters. The crosslinkers are or include, for example, epoxides. Excellent results are achieved using epoxides, such as di-epoxides. These epoxides can, for example, be produced via bio-based routes from lignin or aniline, such as glycerol diglycedyl ether, and/or ethylene glycol diglycedyl ether.

Furthermore, preferably, the glue used is at least two-part with a first part comprising said highly branched polyamides and a second part comprising said cross-linkers, wherein, prior to gluing the cellulosic materials, said parts are first joined together and then the glue is applied. applied to the cellulosic materials. The crosslinkers are well distributed here compared to the highly branched polyamides, allowing the adhesive to perform its function well over the entire plate.

In a very preferred embodiment, the adhesive comprises water as a solvent and the adhesive thus forms an aqueous solution that preferably comprises between 50 and 70 weight percent highly branched polyamides. When the glue is two or more parts, this aqueous solution forms, for example, the above-mentioned first part of the glue or this aqueous solution is obtained by joining the parts of the glue together. During the gluing of the cellulosic materials, the water causes the cellulosic materials to become wet and there is even a slight penetration of the cell wall. With the help of this glue, the cellulosic materials can be connected very well to each other due to the good contact between the glue and the cellulosic materials. Using water as a solvent, contact between the adhesive and the cellulosic materials is possible on almost the entire outer surface of the cellulosic materials.

15 BE2022/5071

Also preferably, the adhesive has a viscosity of at most 20,000 mPa.s, preferably at most 2,000 mPa.s, at 20°C and 1.013 bar. If the glue is two or more parts, the above refers, for example, to the above-mentioned first part of the glue, or to the glue after the parts have been joined. This low viscosity ensures that the adhesive makes good contact with the cellulosic materials and also ensures good pressability of the glued cellulosic materials. This low viscosity can be achieved, for example, with the help of water, where this water serves as a solvent for the highly branched polyamides.

In a preferred embodiment, pressing takes place at a temperature between 150°C and 250°C, with a pressing pressure between 1.5 and 5 N/mm? and this for at least 3 seconds per mm of sheet thickness. The pressing time can be, for example, 5 to 7 seconds per mm of sheet thickness. These are ideal conditions to produce 3-layer chipboards. A continuous or discontinuous press can be used. Preferably, surfaces at the top and bottom are covered with water, for example between 10 and 50g/m². water, sprayed, so as to favor heat transfer to the center of the plate and reduce the total pressing time.

In a specific embodiment, the cellulosic material is covered with glue by atomization, by friction between the wood particles or a combination of both techniques. This ensures good adhesion of the cellulosic material. This concerns a similar or the same adhesive that is applied when using current UF adhesives, as a result of which an existing adhesive step of an existing production process does not have to be adapted or only to a limited extent to the adhesive according to the invention.

This invention also concerns glue for connecting cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, into plates where the glue is based on highly branched polyamides. This glue is the glue used to manufacture plates according to the method described above. The advantages and embodiments of the plate shown and described above in the method according to the invention also apply to this glue. Surprisingly, it was found that such an adhesive is extremely suitable for cellulosic

16 BE2022/5071 to glue materials, such as wood fibers or other vegetable fibres, wood chips, wood layers and wood chips together to form panels by pressing.

The highly branched polyamides are preferably obtained by polycondensation of amino acids, whereby these amino acids are preferably selected from the group containing arginine, glutamine, asparagine and lysine.

In a preferred embodiment, the highly branched polyamides comprise a first group of highly branched polyamides with a molecular weight between 500 and 100,000 g/mol, preferably between 5000 and 50,000 g/mol and even more preferably between 10,000 and 25,000 g/mol. mol, and wherein preferably the highly branched polyamides comprise a second group of highly branched polyamides, wherein the average molecular weight of the first group of highly branched polyamides is at least 3 times higher, preferably at least 5 times higher than the average molecular weight of the second group of highly branched polyamides and/or wherein the average molecular weight of the first group of highly branched polyamides is at most 15 times higher, preferably at most 10 times higher, than the average molecular weight of the second group of highly branched polyamides and wherein furthermore preferably , the second group of highly branched polyamides constitutes between 5 and 30 percent by weight of the total weight of the highly branched polyamides, preferably between 10 and 20 percent by weight.

In a specific embodiment the adhesive comprises crosslinkers, wherein these crosslinkers are preferably selected from the group comprising polyketones, polyesters, isocyanate dispersions, epoxides, glyoxal and other dialdehydes and wherein the weight ratio of crosslinkers on the highly branched polyamides is also preferably between 0. 02 and 0.15. The adhesive can be a one-part adhesive in which all components have already been pre-mixed and are therefore stored as one whole. The adhesive can also be at least two-part, wherein the adhesive comprises a first part with the highly branched polyamides and a second part with the crosslinkers, and wherein the different parts are mixed together, for example, before gluing. The crosslinkers are or include, for example, polyesters, where these polyesters are preferably dispersed

17 BE2022/5071 and/or unsaturated polyesters. The crosslinkers are or include, for example, epoxides. Excellent results are achieved using epoxides, such asdiepoxides. These epoxides can, for example, be produced via bio-based routes from lignin or aniline, such as glycerol diglycedyl ether, and/or ethylene glycol diglycedyl ether.

In a preferred embodiment, the adhesive comprises water as a solvent, thus forming an aqueous solution that preferably comprises 50 to 70 percent by weight highly branched polyamides. When the glue is two or more parts, this aqueous solution forms, for example, the above-mentioned first part of the glue or this aqueous solution is formed by joining the said parts.

The adhesive preferably has a viscosity of at most 20,000 mPa.s, preferably at most 2,000 mPa.s, at 20°C and 1.013 bar. If the glue is two or more parts, the above refers, for example, to the above-mentioned first part of the glue or the above refers to the glue obtained by joining the above-mentioned parts.

An alternative embodiment of the invention concerns an adhesive for connecting insulating materials, such as glass wool, rock wool, etc., for example to form mats, wherein the adhesive is an adhesive based on highly branched polyamides. The preferred embodiments of the adhesive as shown above also apply to this alternative embodiment. Insulating material such as glass wool, rock wool, etc. is then formed with the help of this glue. The invention therefore concerns an insulating material, such as glass wool or rock wool, comprising an adhesive based on highly branched polyamides and also a method for manufacturing insulating material, such as glass wool or rock wool, wherein an adhesive based on highly branched polyamides is provided.

According to a different variant, the invention concerns a method for producing a basic raw material comprising amino acids, wherein this basic raw material can be used for producing highly branched polyamides, preferably by

18 BE2022/5071 polycondensation of the amino acids of the basic raw material.

The basic raw material is preferably obtained by fermentation, whereby this fermentation is preferably carried out by bacteria.

This basic raw material is then used to form hyperbranched polyamides by, for example, allowing polycondensation of the amino acids present to take place at a certain temperature, for example between 120°C and 180°C, for a number of hours, for example in the presence of any catalysts and/or a strong base, such as KOH.

Specific embodiments of the deviating variant are shown in the non-exhaustive list below.

Combinations of features from this non-exhaustive list are possible, as long as they do not contradict each other:

e Bacteria are provided that are capable of producing targeted amino acids via fermentation.

For example, bacteria can be provided that are able to produce mainly lysine and, for example, in smaller quantities one or more other amino acids such as glutamine,

wherein the percentage of other amino acids preferably amounts to at most 20%, preferably at most 10% of the total amount of amino acids produced.

These bacteria then produce a basic raw material comprising amino acids, whereby this basic raw material can be referred to as an industrial quality lysine source.

The standards for an industrial grade lysine source are lower than those for a food or feed lysine source;

e The basic raw material includes amino acids from the group containing arginine, glutamine, asparagine and lysine.

The basic raw material can comprise one, a combination of 2, a combination of 3 or all amino acids from the above group;

e The basic raw material comprising amino acids is produced via fermentation by bacteria, whereby one or more carbohydrate sources and one or more ammonium sources are provided for the fermentation.

The one or more ammonium sources include, for example, one or more ammonium salts, such as ammonium sulphate or diammonium phosphate.

The one or more carbohydrate sources include, for example, sucrose, glucose, cellulose, hemicellulose or lignin.

The carbohydrate sources are, for example, molasses,

19 BE2022/5071 starch hydrolysates, wood-containing sources, recycled sources such as recycled MDF or recycled chipboard; e The basic raw material comprising amino acids is produced via fermentation by bacteria. These bacteria can be, for example, Corynebacterium and/or

E. coli bacteria are; e The basic raw material is produced using L-Lysine producing bacterial strains. These bacterial strains can be, for example, Corynebacterium and/or E. coli bacteria; e The fermentation takes place at a pH between 7 and 8, preferably between 7.3 and 7.7 and/or at a temperature between 28°C and 35°C, preferably between 30°C and 33°C ; e The fermentation takes place in a reactor with agitator 'stirred tank reactor' e The fermentation takes place in batch, fed batch mode or continuously; e Additives are added to increase the yield of a certain amino acid, such as L-Lysine, during fermentation.

With the aim of better demonstrating the features of the invention, some preferred embodiments are described below, by way of example without any limitation.

A first example of a panel according to the invention is a 3-layer chipboard comprising two outer covering layers and a central layer. The central layer comprises coarse wood chips that may or may not originate from wood waste and/or recycled chipboards and the top layers comprise finer wood chips. The wood chips are connected here using an adhesive based on highly branched polyamides.

A second example of a panel according to the invention is a wood fiber board, such as an MDF or HDF board. This wood fiber board is single-layered and contains wood fibers and an adhesive based on highly branched polyamides.

These adhesives have the following properties:

20 BE2022/5071 - the highly branched polyamides are obtained by polycondensation of amino acids that mainly include lysine. For example, in addition to lysine, which is preferably L-lysine, a small amount of glutamine is present. For example, glutamine makes up a maximum of 5% by weight of the amino acids present. The amino acids mentioned come from a basic raw material comprising amino acids.

This basic raw material is obtained, for example, by the fermentation of bacteria, in which these bacteria specifically form lysine; - the highly branched polyamides comprise a first group of highly branched polyamides that make up between 80 and 90 percent by weight of the highly branched polyamides and a second group of highly branched polyamides that make up the remaining percent by weight of the highly branched polyamides. The first group of highly branched polyamides have an average molecular weight between 10,000 and 25,000 g/mol and the second group of highly branched polyamides have an average molecular weight that is between 5 and 10 times lower than the average molecular weight of the first group. branched polyamides; -the adhesive comprises crosslinkers, such as epoxides, where the weight ratio of crosslinkers on the highly branched polyamides is between 0.02 and 0.15;

In the 3-layer chipboard, the glue is the same glue for the different layers, and furthermore, in the central layer the weight ratio of highly branched polyamides to cellulosic materials is between 4 and 5 weight percent, in the case of the covering layers the weight ratio is highly branched polyamides to cellulosic materials. located between 7.5 and 8.5 percent by weight. So more glue is used for the covering layers here than for the central layer. In this way it is ensured that the cellulosic materials at the level of the coating layers do not undesirably separate from each other. The use of more glue for the covering layers is not superfluous, as covering layers consist of finer particles, which greatly increases the total surface area to be glued.

This chipboard can be formed as follows. The wood chips are glued in a drum gluer with a rapidly rotating rotor, where the glue is not added by atomization. The glue used is, for example, a two-part glue comprising a first part containing the highly branched polyamides and a second part comprising the

21 BE2022/5071 crosslinkers. These two parts are mixed prior to gluing, so that the glue comprises the crosslinkers mentioned and the highly branched polyamides. This adhesive is an aqueous solution containing 50 to 70 percent by weight highly branched polyamides. This adhesive has a viscosity of maximum 2,000 mPa.s, at 20°C and 1.013 bar. After gluing, the glued wood chips are pressed together at 200°C and the pressure is off

A4N/mm? during the initial phase, reducing to 2N/mm? and this for about 5 to 9 seconds/mm plate thickness. This pressing is done using a continuous press to form plate-shaped material. This plate-shaped material is sawn into plates with the desired dimensions.

Claims (23)

22 BE2022/5071 Conclusions 1.- A board comprising cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, and an adhesive that connects these cellulosic materials, characterized in that the adhesive is an adhesive based on highly branched polyamides. 2. - A plate according to claim 1, wherein said highly branched polyamides are obtained by polycondensation of amino acids, wherein these amino acids are preferably selected from the group containing arginine, glutamine, asparagine and lysine. 3. - A sheet according to any of the preceding claims, wherein the highly branched polyamides comprise a first group of highly branched polyamides with a molecular weight between 500 and 100,000 g/mol, preferably between 5000 and 50,000 g/mol and even more preferably between 10,000 and 25,000 g/mol and wherein the first group of highly branched polyamides preferably constitutes at least 60 percent by weight of the highly branched polyamides, more preferably at least 80 percent by weight. 4.- A plate according to any of the preceding claims, wherein the plate comprises one or more layers, wherein at least one said layer comprises said cellulosic materials and said glue, wherein preferably in this layer the weight ratio of highly branched polyamides to cellulosic materials lies is between 0.03 and 0.15. 5.- A plate according to claim 4, wherein the plate comprises three or more layers, being two outermost covering layers, and one or more central layers, wherein at least one central layer comprises said cellulosic materials and said glue, and wherein the covering layers each comprise cellulosic materials and an adhesive based on highly branched polyamides, where the weight ratio of highly branched polyamides to cellulosic materials in the covering layers is higher than the weight ratio high 23 BE2022/5071 branched polyamides on cellulosic materials at the latter central layer. 6. Sheet according to any of the preceding claims, wherein the highly branched polyamides comprise a first group of highly branched polyamides and a second group of highly branched polyamides, wherein the average molecular weight of the first group of highly branched polyamides is at least 3 times higher, preferably is at least 5 times higher than the average molecular weight of the second group of highly branched polyamides and/or where the average molecular weight of the first group of highly branched polyamides is at most 15 times higher, preferably at most 10 times higher, than the average molecular weight of the second group of highly branched polyamides. 7. Sheet according to claim 6, wherein the second group of highly branched polyamides constitutes between 5 and 30 weight percent of the total weight of the highly branched polyamides, preferably between 10 and 20 weight percent. 8. Plate according to any of the preceding claims, wherein the adhesive comprises crosslinkers, wherein preferably these crosslinkers are selected from the group comprising polyketones, polyesters, isocyanate dispersions, epoxides, glyoxal and other dialdehydes. 9. Plate according to claim 8, wherein the weight ratio of crosslinkers on the highly branched polyamides is between 0.02 and 0.15. 10.- Method for forming plates comprising cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, wherein cellulosic materials are provided and a glue is applied to these cellulosic materials, after which these glued cellulosic materials are pressed into a plate-shaped material for forming plates, characterized in that the adhesive is an adhesive based on highly branched polyamides. 11. - Method according to claim 10, wherein said highly branched polyamides of the adhesive are obtained by polycondensation of amino acids, wherein these 24 BE2022/5071 amino acids are preferably selected from the group containing arginine, glutamine, asparagine and lysine. 12. - Method according to claim 10 or 11, wherein the highly branched polyamides comprise a first group of highly branched polyamides with a molecular weight between 500 and 100,000 g/mol, preferably between 5000 and 50,000 g/mol and even more preferably between 10,000 and 25,000 g/mol and that preferably the highly branched polyamides comprise a second group of highly branched polyamides, wherein the average molecular weight of the first group of highly branched polyamides is at least 3 times higher, preferably at least 5 times higher than the average molecular weight of the second group of highly branched polyamides and/or wherein the average molecular weight of the first group of highly branched polyamides is at most times higher, preferably at most 10 times higher, than the average molecular weight of the second group of highly branched polyamides , and wherein further preferably, the second group of highly branched polyamides constitutes between 5 and 30 weight percent of the total weight of the highly branched polyamides, preferably between 10 and 20 weight percent. 13. - Method according to any one of claims 10 to 12, wherein the plate comprises one or more layers, wherein these layers are pressed together and wherein at least one said layer comprises said cellulosic materials and said glue, wherein the weight ratio of this layer is high branched polyamides on cellulosic materials is between 0.03 and 0.15, and wherein the plate preferably consists of three or more layers comprising outermost covering layers, and one or more central layers, wherein at least one central layer comprises the said cellulosic materials and the said adhesive, and wherein the covering layers each comprise cellulosic materials and an adhesive based on highly branched polyamides, wherein the weight ratio of highly branched polyamides to cellulosic materials at the covering layers is higher than the weight ratio of highly branched polyamides to cellulosic materials at the latter central low. 14. - Method according to any one of claims 10 to 13, wherein the adhesive comprises crosslinkers and/or wherein crosslinkers are applied to the cellulosic 25 BE2022/5071 materials, whereby these crosslinkers are preferably selected from the group comprising polyketones, polyesters, isocyanate dispersions, epoxides, glyoxal and other dialdehydes and whereby the weight ratio of crosslinkers on the highly branched polyamides is also preferably between 0.02 and 0 ,15. Method according to any one of claims 10 to 14, wherein the adhesive comprises water as a solvent, thus forming an aqueous solution comprising, preferably, between 50 and 70% by weight highly branched polyamides. Method according to any one of claims 10 to 15, wherein the adhesive has a viscosity of at most 20,000 mPa.s, preferably at most 2,000 mPa.s, at 20°C and 1.013 bar. Method according to any one of claims 10 to 16, wherein the pressing takes place at a temperature between 150°C and 250°C, with a pressing pressure between 1.5 and 5 N/mm? and this for at least 3 seconds per mm of sheet thickness. 18.- Glue for connecting cellulosic materials, such as vegetable fibers and/or wood chips and/or wood parts, into panels, characterized by the fact that the glue is based on highly branched polyamides. 19. - Glue according to claim 18, wherein the highly branched polyamides are obtained by polycondensation of amino acids, wherein these amino acids are preferably selected from the group containing arginine, glutamine, asparagine and lysine. 20.- Glue according to claim 18 or 19, wherein the highly branched polyamides comprise a first group of highly branched polyamides with a molecular weight between 500 and 100,000 g/mol, preferably between 5000 and 50,000 g/mol and even more preferably between 10,000 and 25,000 g/mol and that preferably the highly branched polyamides comprise a second group of highly branched polyamides, wherein the average molecular weight of the first group of highly branched polyamides is at least 3 times higher, preferably at least 5 times higher than the average molecular weight of the second group of highly branched polyamides and/or where the average molecular weight of the first group of highly branched polyamides is not more than 15 times 26 BE2022/5071 is higher, preferably at most 10 times higher, than the average molecular weight of the second group of highly branched polyamides and whereby, preferably, the second group of highly branched polyamides accounts for between 5 and 30 weight percent of the total weight of the highly branched polyamides, preferably between 10 and 20 percent by weight. 21. - Glue according to any one of claims 18 to 20, wherein the glue comprises crosslinkers, wherein preferably these crosslinkers are selected from the group comprising polyketones, polyesters, isocyanate dispersions, epoxides, glyoxal and other dialdehydes and wherein also preferably the weight ratio of crosslinkers on the highly branched polyamides is between 0.02 and 0.15. 22. - Glue according to any one of claims 18 to 21, wherein the glue comprises water as a solvent and thus forms an aqueous solution comprising, preferably, between 50 and 70% by weight highly branched polyamides. 23. - Glue according to any one of claims 18 to 22, wherein the glue has a viscosity of at most 20,000 mPa.s, preferably at most 2,000 mPa.s, at 20°C and 1.013 bar.