FI127961B

FI127961B - A method of forming a binder composition

Info

Publication number: FI127961B
Application number: FI20185379A
Authority: FI
Inventors: Harri Lepistö; Seppo Havuaho; Marko Lindgren; John Quibuyen; Peter Lingenfelter
Original assignee: Prefere Resins Finland Oy
Priority date: 2018-04-20
Filing date: 2018-04-20
Publication date: 2019-06-14
Also published as: FI20185379A1; FI20185379A

Abstract

According to an example aspect of the present invention, there is provided a binder composition suitable for the production of composite lignocellulose products, comprising an aldehyde based resin and a catalyst, combined into dry grains which are capable of being dissolved in water to provide a liquid binder.

Description

A method of forming a binder composition

FIELD [0001] The present invention relates to binder compositions that are suitable for the production of composite lignocellulose products, such as composite wood panels. Particularly, the present invention relates to aldehyde based resins.

BACKGROUND [0002] Traditionally liquid phenol-formaldehyde resin products have been used to produce exterior grade wooden panels e.g. plywood and laminated veneer lumber (LVL). In Europe the current state of the art glue systems are 3-component systems where liquid resole resin, powder hardener and water are mixed to a usable glue mixture. The purpose of using powder hardeners is to improve the gluing efficiency by lowering the gluing costs and to improve glue behavior during panel production. Hardener mixtures may include extenders, e.g. starches, wheat flours, wood flours; fillers, e.g. inorganic fillers such as calcium carbonate (CaCCU); and catalysts, e.g. potassium carbonate (K2CO3). Water addition is done to adjust the glue viscosity to a suitable gluing level. Water addition may be changed on a daily basis due to viscosity variation. Main cause for viscosity variation in 20 the glue mixture is the fact that liquid resole resins have a limited storage stability and that the viscosity will increase every day due to resin condensation reactions. Normal storage stability at 20 °C degrees for plywood and LVL resins with formaldehyde to phenol molar ratio (F/P) 1.5 to 2.8, solids content 30 to 70%, and alkalinity 3 to 12% is between 2 to 5 weeks. For plywood and LVL resins the storage stability has traditionally been measured 25 by measuring resin viscosity (in a selected temperature). Due to the moderately short storage stability and the low solids content (high transportation costs), resin producers are serving only local panel producers.

[0003] As discussed above, in the prior art the common practice is to combine the phenolic resin with water, hardeners and other additives to prepare a glue mixture for 30 application to sheet material, such as wood veneer, by means of conventional roll coating

20185379 prh 23 -01- 2019 or spray coating processes. Glue mixtures of this type are usually of advanced viscosity and cannot be held for any appreciable time in storage at normal room temperatures without setting up. It has been the practice therefore to mix this type of resin adhesive at the manufacturing plant in relatively small quantities since it could not be premixed and 5 shipped in bulk.

[0004] In the prior art, besides roll coating and spray methods, also curtain coating has been used as a method for spreading a ready glue mixture on the surface of wood veneers. Curtain coating is a process that creates an uninterrupted curtain of fluid that falls onto a substrate. The substrate is transported on a conveyor belt at a regulated speed 10 through the curtain to ensure an even coat. The curtain is created by using a slit at the base of the holding tank, allowing the liquid to fall upon the substrate.

[0005] US 3451374 A describes a gravity-type curtain coating apparatus for applying a thin coat of thermosetting resin adhesive, such as phenolic or phenolic derivative base resin, to sheet laminate material.

[0006] During recent years exterior wooden panel producers have been demanding more output capacity from their own production units and this has forced also resin producers to develop more reactive glue systems. Degree of condensation, F/P-molar ratio, resin solids content, and alkalinity are the main four parameters which define the resin behavior and physical properties, e.g. storage stability and reactivity. Traditionally 20 reactivity increase has been reached by optimizing resin parameters but normally by losing the storage stability. Therefore, this has even more localized the panel resin markets.

[0007] In the phenol-formaldehyde market, there are alternative glue systems for plywood and LVL production compared to 3-component glue systems: Ready to Use (RTU) glues and powder resins. RTU glues are liquid binder compositions containing 25 small amounts of extenders, e.g. flours and starches. Challenges are therefore similar to those present in plain resole resins and 3-component glue systems, such as limited storage stability and high transportation costs due to high water content.

[0008] Powder resins are produced in similar batch reactors as liquid resole resins. In the final production step of a powder resin, a liquid resin is thermally dried by a spray 30 method to produce a dry powder. In a typical spray drying process for manufacturing a powder resin, a liquid resin is atomized to fine droplets and mixed with hot air to evaporate

20185379 prh 23 -01- 2019 the water from the resin droplets. The temperature of the resin is usually close to the boiling water temperature or higher, usually up to 150 - 200 °C. A thermal drying unit that is used has a moderately high investment cost, but also operational costs are high due to the use of thermal energy. Thermal energy is used when sprayed resin droplets are dried by 5 using air. All these factors affect the price of the powder resins.

[0009] Powder resin production is challenging due to difficulties in optimizing the process parameters and controlling the particle size distribution. The composition or properties (such as F/P-molar ratio, solids content, alkalinity, degree of condensation, presence of additives or hardeners) of the liquid mixture to be dried can only be varied 10 within rather strict limits. Spray drying necessitates that the liquid mixture have a low viscosity and low alkalinity in order to generate small enough droplets. If the droplets are too large, they will accumulate and form deposits on the walls of the spray drying chamber. Such undesired deposit of resin is severely detrimental to the spray drying operation by reducing powder resin yield, increasing fire hazard, frequently shutting down 15 operation for cleaning, and undesirably increasing particle size.

[0010] Powder resin technology is frequently used by panel producers with remote locations due to its long storage stability. Preparation of glue from a powder resin requires that the remaining components of the glue are obtained separately and mixed with the resin in suitable proportions.

[0011] Spray drying of binder compositions has been studied previously to some extent. For example, the publication US 2013/0085211 Al describes preparation of particulates from mixtures of an aqueous phenol-formaldehyde resin together with fillers and extenders (for example peanut shells or corn flour) by spray-drying at temperatures in the range 80 to 160 °C.

[0012] There are obvious challenges in the currently available aldehyde based glue systems particularly with regard to ease of use, storage stability, and transportation costs.

[0013] US 4961795 describes a composition and a process for bonding lignocellulosic material under heat and pressure. According to the process, a curing agent is combined with a binder which is an alkaline phenol-formaldehyde resin.

[0014] US 3998906 describes an aldehyde condensation copolymer which is formed by co-condensing 90% - 10% by weight of an essentially linear non-crosslinkable aldehyde

20185379 prh 23 -01- 2019 condensation prepolymer with 10% - 90% by weight of a highly thermosettable and crosslinkable aldehyde condensation prepolymer.

[0015] In GB 1404042, granular phenol-formaldehyde resin is produced by spraying a liquid material containing an initial condensation product of a phenol-aldehyde resin into 5 an atmosphere heated to a temperature higher than the melting point of the initial resin and bringing the liquid resin particles thus produced into contact with a gas, e.g. air, at a temperature lower than the melting point of said initial resin to solidify the particles.

[0016] US 5637658 describes a process for the production of a modified phenolaldehyde resin which may form a binder system when combined with a curing agent which 10 includes an additional source of an aldehyde, e.g., a phenol-formaldehyde resin.

[0017] US 4046734 describes aminoplast or phenoplast compositions that are manufactured by drying an aqueous solution of a phenol-formaldehyde resin, a ureaformaldehyde resin or an optionally phenol-modified melamine-formaldehyde resin in a thin layer evaporator or roller drier. The compositions are used for the manufacture of 15 crockery, household articles and technical components for the electrical industry.

[0018] Ullmann’s Encyclopedia of Industrial Chemistry (Weinheim, Wiley-VCH,

2005) provides an overview of phenolic resins, written by Wolfgang Hesse (pages 1-16).

[0019] In the article written by M. Gupta et al., “Shelf Life of Phenolic Resole Resins” (Polymer Engineering and Science, 1987, Vol. 27, No. 13, pages 976-978), the 20 viscosity, number-average and weight-average molecular weights (measured by gel permeation chromatography), and carbon-13 nuclear magnetic resonance (NMR) were used to monitor the changes in phenolic resoles as a function of time and pH.

[0020] Handbook of Industrial Drying (3rd edition, Taylor & Francis Group, LLC,

2006) provides information about drum dryers and drum dried products in a chapter 25 written by Wan Ramli Wan Daud (pages 203-211).

[0021] GB 2030587 A describes a flake-like, particulate mass consisting essentially of flakes having a dry thickness in excess of about 25 microns, said flakes consisting essentially of a solid, non-toxic, biodegradable, water soluble essentially hexahydric alcohol matrix which is essentially free of chemically unassociated water, and entrapped 30 within and uniformly distributed through the matrix, solid particles having an average

20185379 prh 23 -01- 2019 particle size less than 5% of the thickness of the flakes, the particles being generally inert towards water and hexahydric alcohols and generally water-insoluble and having a melting point greater than 100 °C.

SUMMARY OF THE INVENTION [0022] There is a need for providing or a glue mixture with high reactivity and high viscosity and at the same time with extended storage stability.

[0023] There is a further need for providing a plain resin or a resin mixture with high reactivity and high viscosity and at the same time with extended storage stability.

[0024] There is a further need for simplifying the process of glue preparation that needs to be done by the user near the point of usage.

[0025] There is a further need for providing more compact forms of resins and glues in order to reduce transportation costs.

[0026] We have observed that at least some of these problems can be solved by the 15 present invention.

[0027] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0028] According to a first aspect of the present invention, there is provided a binder composition suitable for the production of composite lignocellulose products, comprising 20 an aldehyde based resin, and a catalyst, combined into dry grains which are capable of being dissolved in water to provide a liquid binder.

[0029] According to a second aspect of the present invention, there is provided a binder composition obtained by providing a liquid mixture of an aldehyde based resin, a catalyst, and optionally one or more components selected from fillers, extenders and 25 additives; forming a layer of the liquid mixture on a substrate; drying the layer; and disintegrating the layer at least partly into the form of grains.

[0030] According to a third aspect of the present invention, there is provided a method of forming a binder composition suitable for the production of composite

20185379 prh 23 -01- 2019 lignocellulose products, comprising the steps of forming a liquid mixture of an aldehyde based resin and a catalyst; depositing said liquid mixture on a substrate so as to form a film thereon; drying said film; and disintegrating said film to form flakes which are capable of being dissolved in water to provide a liquid binder.

[0031] According to a fourth aspect of the present invention, there is provided a liquid binder comprising an aqueous solution of the binder composition according to the invention.

[0032] According to a fifth aspect of the present invention, there is provided use of curtain coating in combination with film drying for forming a dry shelf-stable resin or a 10 dry shelf-stable binder composition from a liquid resin or from a liquid mixture of an aldehyde based resin and a catalyst, respectively, suitable for the production of composite lignocellulose products.

[0033] According to a further aspect of the present invention, there is provided a resin suitable for the production of composite lignocellulose products, in the form of dry 15 grains or flakes which are capable of being dissolved in water to provide a liquid resin that can be used for the production of a liquid binder.

[0034] According to an aspect of the present invention, there is provided a binder composition suitable for the production of composite lignocellulose products, comprising an aldehyde based resin, and a catalyst, formed into dry grains which are capable of being 20 dissolved in water to provide a liquid binder.

[0035] The present invention provides considerable advantages. Particularly, by using the present invention it is possible to produce dried resin dried glue which can be dispersed to water in order to prepare a liquid resin or a glue mixture (a liquid binder) that is directly applicable to a gluing process.

[0036] An advantage is that the present invention provides a method for extending the shelflife of reactive resins and glue mixtures.

[0037] A further advantage is that the present invention provides an effective method for drying resins, optionally together with hardener mixtures or any other components needed in a particular glue mixture. Such hardener mixtures may contain 30 fillers, extenders and/or catalysts.

20185379 prh 23 -01- 2019 [0038] The binder compositions according to the present invention are bulk transportable, easy to use, and suitable for bulk storage in silos or big bags. Further, they can serve the purposes of both small-scale and large-scale companies or industries that utilize resin-based glue mixtures.

[0039] The binder compositions according to the present invention provide improved glue systems with optimized gluing costs.

BRIEF DESCRIPTION OF THE DRAWINGS [0040] FIGURE 1 illustrates dried glue of Example 1 after 4 weeks storing time;

[0041] FIGURE 2 illustrates a production process for dried glue according to one embodiment.

EMBODIMENTS [0042] DEFINITIONS [0043] In the present context, the term “glue” or “glue mixture” refers to a liquid binder composition that is ready to be used as a liquid binder in a gluing process.

[0044] In the present context, the term “dried glue” or “dried glue mixture” refers to a binder composition the moisture content of which has been decreased.

[0045] Tn the present context, the term “hardener” or “hardener mixture” refers to 20 compounds and/or compositions that can be added to a glue mixture in order to improve gluing efficiency, glue structure or glue behaviour.

[0046] The present invention is directed to a dried binder composition in the form of grains that can be dissolved to water, and to a method for drying or reducing the moisture content of an aqueous glue mixture, or part of its components, temporarily, for example for 25 storage or transport purposes, without impairing its gluing properties as a consequence of the drying step. In the present invention, it has been observed that the reactivity of the glue mixture, particularly the ability of the glue mixture to bond, can be maintained: the gluing

20185379 prh 23 -01- 2019 strength of the solubilized grains is comparable to the gluing strength of the glue mixture before the drying.

[0047] According to an embodiment, the composition to be dried comprises an aldehyde based resin and a catalyst. However, drying of a plain aqueous aldehyde based 5 resin is also possible by using the present invention, in which case drying should preferably be carried out by a curtain coater.

[0048] According to an embodiment, the grains have a smallest dimension of 0.01 to 20 mm, in particular 0.5 to 10 mm, for example 0.8 to 5 mm, and a largest dimension greater than the smallest dimension and up to 100 mm.

[0049] According to an embodiment, the dried binder composition has a solids content of at least 60%, for example at least 80 %, in particular at least 95 % or more calculated from the weight of the composition. High solids content increases the storage stability of the binder composition.

[0050] According to an embodiment, the grains are essentially in the form of flakes 15 obtained by disintegrating a film comprising the aldehyde based resin and the catalyst.

[0051] According to an embodiment, the grains are essentially in the form of flakes obtained by disintegrating a film having a thickness of 0.001 to 2 mm, in particular 0.5 to 10 mm, for example 0.8 to 5 mm.

[0052] According to an embodiment, the grains have an alkalinity of 0.5 to 18 %, in 20 particular 4 to 9 %, for example 6 to 8 %. High alkalinity is advantageous as it enables polymer molecules in the resin to have a high molecular weight.

[0053] According to an embodiment, the bulk density of the grains is in the range of 0.1 to 2.5 g/cm³.

[0054] According to an embodiment, the catalyst is an alkaline component. The 25 alkaline component may be selected from the group of alkali and earth alkali metal hydroxides and carbonates and bicarbonates. For example, the alkaline component may be Na₂CO₃, K₂CO₃ or NaOH.

[0055] According to another embodiment, particularly if the aldehyde based resin contains urea, the catalyst is an acidic component.

20185379 prh 23 -01- 2019 [0056] According to an embodiment, the aldehyde based resin is selected from the group of urea-aldehyde resins, melamine-aldehyde resins, phenol-aldehyde resins, melamine-urea-aldehyde resins, phenol-urea-aldehyde resin, resorcinol-aldehyde resins, phenol-resorcinol-aldehyde resins, and combinations thereof [0057] According to an embodiment, the aldehyde based resin is selected from the group of urea-formaldehyde resins, melamine-formaldehyde resins, urea-melamineformaldehyde resins, resorcinol-formaldehyde resins and phenol-resorcinol-formaldehyde resins.

[0058] According to an embodiment, the aldehyde based resin is a phenol10 formaldehyde resin, in particular a phenol-formaldehyde resin having a formaldehyde to phenol molar ratio of about 1:1 to 5:1, for example 2.2 to 2.85.

[0059] According to an embodiment, the binder composition comprises further components selected from the group of fillers and extenders and combinations thereof.

[0060] According to an embodiment, the binder composition comprises 300 to 700 parts by weight of aldehyde based resin; and 100 to 300 parts by weight of alkaline components and fillers, and optionally extenders, based on the dry weight of the composition.

[0061] According to an embodiment, the binder composition further comprises additives selected from the group of thickeners, tack promoters, foaming agents and 20 surfactants.

[0062] According to an embodiment, the binder composition comprises an aldehyde based resin and a powder hardener. The powder hardener preferably comprises an alkaline component, for example Na2CO3, K2CO3 or NaOH, as a catalyst.

[0063] According to an embodiment, the binder composition has a shelf life, when 25 stored at room temperature at a relative humidity of less than 80 % and in the presence of air, of more than 5 weeks, in particular at least 6 weeks.

[0064] According to an embodiment, the binder composition exhibits essentially no visual change or hygroscopic behavior during more than 5 weeks, in particular during at least 6 weeks.

20185379 prh 23 -01- 2019 [0065] According to an embodiment, the binder composition is capable of being dissolved in water to provide a liquid binder composition containing 30 to 40 % of aldehyde-based resin and having an alkalinity of at least 0.5 %, for example at least 5 %. A liquid binder composition with these properties is particularly suitable for use as an 5 adhesive in the production of composite wood panels.

[0066] Upon dissolving the dry binder composition into water, it is possible to finetune the structure and properties of the final glue mixture by adding hardeners, fillers, extenders, catalysts or other additives or combinations thereof. In this way the user of the glue mixture is able to benefit from the storage stability of the dry binder composition 10 while still being able to tailor the glue mixture for different purposes.

[0067] The binder composition according to the present invention can be prepared for example by the following method: providing a liquid mixture of an aldehyde based resin, a catalyst and optionally one or more components selected from fillers, extenders and additives; forming a layer of the liquid mixture on a substrate; drying the layer; and 15 disintegrating the layer at least partly into the form of grains.

[0068] According to an embodiment, the layer is disintegrated together with the substrate upon which it has been deposited. The substrate can be selected so that it can serve the function of filler or other additive in the glue mixture. For example, a paperbased substrate with a sufficient wet strength can be used as the substrate, disintegrated 20 together with the dried film, and in this way included as a filler in the glue mixture.

[0069] The present invention also provides a method of forming a binder composition suitable for the production of composite lignocellulose products, comprising the steps of: forming a liquid mixture of an aldehyde based resin and a catalyst; depositing said liquid mixture on a substrate so as to form a film thereon; drying said film; and 25 disintegrating said film to form flakes which are capable of being dissolved in water to provide a liquid binder.

[0070] According to an embodiment, the liquid mixture of the aldehyde based resin and a catalyst, optionally together with at least one of fillers, extenders and additives, is deposited on a substrate by curtain coating. Preferably, the catalyst is an alkaline 30 component.

20185379 prh 23 -01- 2019 [0071] According to an embodiment, the viscosity of the aldehyde based resin is in the range of 220 to 500 cP, for example 250 to 450 cP.

[0072] According to an embodiment, the alkalinity of the aldehyde based resin is in the range of 5.0 to 9.0 %, for example 6.0 to 8.5 %.

[0073] According to an embodiment, the solids content of the aldehyde based resin is in the range of 30 % to 70 %, for example 48 to 54 %.

[0074] According to an embodiment, the liquid mixture is deposited upon a substrate selected from the group of metal bands, bands of polymeric bands, fibrous sheets and fibrous webs.

[0075] According to an embodiment, the liquid mixture is deposited on a substrate to form a film having a surface weight of 20 to 500 g/m², in particular 80 to 250 g/m², for example 90 to 150 g/m². A film with a low surface weight can be dried quickly even at moderate temperatures.

[0076] According to an embodiment, the liquid mixture layer is dried at a temperature of about 15 to 100 °C, in particular 20 to 80 °C, preferably for a period of time ranging from 1 minute to 300 minutes. By using a relatively low drying temperature for removing the most part of moisture, it is possible to avoid undesired irreversible chemical reactions, such as hardener gelatinization or resin condensation, which could impair gluing properties.

[0077] According to an embodiment, the dried or drying film is peeled off the substrate to provide flakes preferably having a greatest dimension of 0.01 to 50 mm.

[0078] According to an embodiment, the substrate is a fibrous sheet or web, and the film is disintegrated together with the fibrous sheet or web to provide film flakes containing fibrous material obtained from the sheet or web.

[0079] According to an embodiment, the solids content of the dried film or flakes is at least 80 %, preferably at least 85 %, for example 85 to 95 % by weight or even more. In the dried flakes with a low solids content, the chemical reactivity is low, which makes it possible to store the flakes for extended periods of time. When a sufficiently high solids content, for example 85 %, has been reached, it becomes possible to apply higher drying temperatures as a second drying step, as the reactivity of the binder composition is low. In

20185379 prh 23 -01- 2019 one embodiment, a second drying step is carried out in the temperature of 90 to 180 °C, for example 100 to 110 °C, preferably for a period of time ranging from 1 minute to 60 minutes.

[0080] According to an embodiment, the flakes are dissolved in water, and optionally at least one component selected from the group of aldehyde based resin, formaldehyde, alkaline agents and mixtures thereof is added in order to prepare a liquid binder.

[0081] The present invention also provides a liquid binder which comprises an aqueous solution of the binder composition.

[0082] The present invention introduces a new use of curtain coating in combination with film drying for forming a dry shelf-stable binder composition from a liquid mixture of an aldehyde based resin and a catalyst, which binder composition is suitable for the production of composite lignocellulose products.

[0083] The present invention also introduces a new use of curtain coating in combination with film drying for forming a dry shelf-stable resin from a liquid resin, which dry shelf-stable resin is suitable for the production of composite lignocellulose products.

[0084] In a preferred embodiment, curtain coating is used for spreading the liquid mixture on a support before drying it.

[0085] Advantages of curtain coating include: extremely even and accurate spreading particularly lengthwise; possibility to spread low dosing levels accurately (e.g. 50 - 100 g/m²), which increases the drying rate; and possibility to spread glue mixtures which have a low water amount included in the glue mixture (less water improves drying/evaporation of water). Curtain coating is applicable to liquid mixtures with a high viscosity.

[0086] If curtain coating is applied for spreading the liquid mixture on a support, it is advantageous to include a small amount of catalyst in the liquid mixture to be spread in order to obtain a smoother film and to further speed up the drying process.

[0087] Alternative systems for spreading the liquid mixture (preferably spreading on 30 a support), are liquid extruder, spray-application, roller spreader or foam extruder. In the foam extruder technique, the bulk density of the spread film is low and drying takes place quickly.

[0088] Drying of the film of the liquid mixture can be carried out by using for example a float oven, a heat furnace, a microwave heater or a rotating kiln.

[0089] By using the present invention, dried glue can be prepared with different sized and shaped grains, such as flakes, sheets, or particles. The bulk density of the dry glue can be adjusted for example by milling the dried glue or by compacting the material by any suitable method.

[0090] The binder composition is suitable for the production of composite 10 lignocellulose products, for example composite wood panels, such as particleboard (PB), medium density fibreboard (MDF), oriented strand board (OSB), plywood (PW), glued laminated timber (glulam), laminated veneer lumber (LVL), cross-laminated timber (CLT), parallel strand lumber (PSL), structural composite lumber (SCL), laminated strand lumber (LSL), oriented strand lumber (OSL), finger-joint lumber, I-joists, wood I-beams, roof 15 trusses, floor trusses.

[0091] In the following we present examples describing the production and use of binder compositions according to the invention.

[0092] Example 1 [0093] Raw materials and glue systems [0094]

Drying tests were executed for a 3-component glue mixture where phenol20185379 prh 23 -01- 2019 formaldehyde resin, powder hardener and water were mixed together (see Table 1). Prefere

15J573, Prefere 25J648, and water were used during the laboratory tests. These Prefere products were produced according to the production recipes and the products fulfilled their product specifications. Resin-% was 34.6 %. Resin viscosity (FC6/20C) was 16.3 s.

[0095] Table 1: Recipe for a glue mixture that was dried in Example 1.

Component	(g)
Prefere 15J573	1000
Prefere 25J648	175
Water	170
Total	1345

[0096] Drying and storing [0097] The glue mixture was mixed for 2 hours before curtain coater application to ensure that the glue system was stable during the tests. The glue mixture was prepared by 5 mixing the powder hardener and the resin, after which water was added to the mixture.

Viscosity measurement results from one of the experiments are shown in Table 2. According to the viscosity measurements, all the glue mixtures used during the laboratory tests behaved normally.

[0098] Table 2: Viscosity measurement results.

20185379 prh 23 -01- 2019

Time (h)	Viscosity FC6/25C (s)
0	35.6
1	36.2
2	37.2	Drying of the glue with curtain coater
4	40.3
24	58.8

[0099] The obtained 3-component glue mixture was spread (100 - 120 g/m²) on a plastic support (40 cm x 250 cm), and drying was carried out at 25 - 30 °C for about 60 to 120 minutes. A long drying time was selected to ensure sufficient drying. During drying, the glue peeled off from the plastic support as glue flakes having a largest dimension in the

20185379 prh 23 -01- 2019 range 2 mm to 45 mm. After drying, the dried glue was collected and stored (see Fig. 1). In total 2.5 kg of dried glue flakes were collected during the laboratory tests.

[00100] Drying tests were executed during 17.4. - 30.4.2015. Dried glue flakes were stored in an open plastic container in the Hamina laboratory and thus exposed to temperature and moisture variation. The shortest storage time for the dried glue was about 6 weeks (30.4. - 12.6.2015). No visual change or hygroscopic behavior was observed during the storage time. The bulk density of the prepared dried glue was only 0.3 g/cm³, and with slight milling the density was increased to 0.5 g/cm³. It would be possible to further increase the bulk density by milling the dried glue or by slightly compacting it.

[00101] Depending on the measurement method, the solids content of the dried glue was in the range of 85 to 90 %. Moisture content was measured with 105 °C/2g/3h and with a microwave moisture content analyzer. The solids content of the dried glue is crucial for the overall feasibility of the glue system, for example due to fact that even a small increase in solids content will decrease transportation costs. Due to this fact, additional tests were executed. During laboratory work, a small amount of already dried glue was further dried at elevated temperatures (105 °C) for about 15 minutes to remove remaining water. After the temperature treatment, the dried glue could be solubilized into water.

[00102] During the laboratory tests, the production of dried glue was carried out by utilizing a curtain coater, but glue can also be spread, preferably on a support, with liquid 20 extrusion, a spray unit or a foam spreader. Curtain coating was selected as the spreading method to be used in the tests due to fact that with a curtain coater it was possible to reach a low spreading amount and the drying time was short.

[00103] Gluing with dried glue and gluing results [00104] Softwood plywood panels were glued with a glue mixture that was prepared by mixing dried glue flakes and water. Roller application was used to glue the veneers. Roller application required less glue than any other glue application method available in the Hamina laboratory, and therefore it was selected to produce the test panels. The detailed glue recipe is shown in Table 3, the viscosity measurement results in Table 4, the solids content measurement results in Table 5, and the test panel parameters in Table 6. The

0 resin-% was 3 4.6 %.

[00105] Table 3: Glue recipe.

Glue recipe	Solids (%)	Dried glue
Dried glue flakes (17.4.-30.4.2015)	86%	450
Water		550
Total		1000

[00106] Table 4: Viscosity measurement results.

Time (h)	FC6/25 °C (s)
0	51.0
1	39.5
2	38.3	Gluing

[00107] Table 5: Solids content measurement results for the dried glue produced during 17.4.-30.4.2015.

Solids content for PLW resin (105C/2g/3h)	86.0 %
Micro wave oven (CEM)	89.40 %

20185379 prh 23 -01- 2019 [00108] Table 6: Test panel parameters.

Panel	7 mm x 3.2 mm softwood (Pellos), 21 mm
Veneer moisture	3.6 to 3.8 %
Spreading amount	200 g/m²
Lay up + open time	5 to 25 min
Pre-press	7 min / 0.7 MPa
Time between presses	about 20 to 40 min
Hot pressing
Temperature	140 °C
Time	15 min
Pressure	1.5 MPa (1.5-1.0-0.2)
Panels (stc)	4
QC-test (EN314)	1-surface and core / CLASS 1

20185379 prh 23 -01- 2019 [00109] Glue preparation was started by measuring the required amount of water into a plastic container, after which the mixer unit was started. The required amount of dry glue 5 was measured with a laboratory scale. Dry glue was gradually introduced into water. After all dry glue had been added into the mixture, the prepared glue mixture was mixed for about 10 minutes. After mixing, the viscosity of the glue mixture was measured with Ford Cup 6 at 25 °C. Before the viscosity measurement, the glue sample was adjusted precisely to 25 °C by using a warm water bath.

[00110] Glue mixing was as easy as with any traditional 3-component glue system.

Glue flakes solubilized into water easier than conventional powder resins. Probably due to high speed mixing, the glue contained some air. The prepared glue mixture was used in roller application and no difficulties were observed during the gluing process. Technically the solubilized dried glue behaved in the same way as it did before the drying process.

Gluing quality and pre-press tack were normal. The gluing results are presented in Table 7.

[00111] Table 7: Gluing results.

Panel samples	Lay up + open time	Time between presses	QC-Test (EN314)	Strength	Wood failure (dry)	Pre-press tack before hot pressing
X	Sx	X	Sx
U1-U2	5 min	20 min	1-surface	0.92	0.30	99	3	5
core	1.29	0.42	76	32
U3-U4	25 min	27 min	1-surface	1.34	0.43	93	9	5
core	1.20	0.42	97	6

[00112] Example 2 [00113] Production method for dried glue [00114]

In the following, with reference to Fig. 2, we describe a process for preparing dried glue according to an embodiment.

[00115] Production of dried glue is started by mixing resin, powder hardener and water in a glue mixing unit 21. The prepared glue mixture is then spread on a continuous plastic support 23 by means of a curtain coater 22.

20185379 prh 23 -01- 2019 [00116] After the glue has been spread on the plastic support, the water in the glue mixture starts to evaporate in the evaporation zone 24. Optionally, evaporation can be speeded up by increasing the drying temperature and/or by using circulated air. When enough water has been evaporated, the plastic support enters into a float oven 27 for drying.

[00117] Inside the float oven 27, in the drying zone 25, most of the water is evaporated and most of the glue is dried and stabilized. To avoid sticking problems, the final part of the float oven contains a short cooling zone 26. After the cooling zone, the dried glue is peeled off in the form of flakes 28 from the support for example with an air knife. The flakes are collected into a storage silo 29.

[00118] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for

20185379 prh 23 -01- 2019 the purpose of describing particular embodiments only and is not intended to be limiting.

[00119] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present 5 invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[00120] As used herein, a plurality of items, structural elements, compositional 10 elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, 15 various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[00121] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In this description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or 25 more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[00122] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary 30 skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[00123] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, that is, a 5 singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY [00124] At least some embodiments of the present invention find industrial application in the manufacturing of composite wood panels.

20185379 prh 23 -01- 2019

REFERENCE SIGNS LIST

21	glue mixing unit
22	curtain coater
23	continuous line with plastic support
24	evaporation zone
25	drying zone
26	chill (cooling) zone
27	float oven
28	dried glue flakes
29	storage silo

Patent Literature

Claims

CLAIMS:

A process for preparing a binder composition, which is suitable for making composite lignocellulosic products, comprising the steps of:

- forming a liquid mixture of an aldehyde-based resin and a catalyst, preferably a basic component;

- depositing said liquid mixture on the substrate to form a film thereon;

drying said film to disintegrate said film into chips which can be dissolved in water to provide a liquid binder, characterized in that the substrate is a fiber sheet or web, the method comprising disintegrating the film with a fiber sheet or web to provide film chips containing .

The process of claim 1, wherein the liquid mixture of the aldehyde-based resin and catalyst, optionally together with at least one of a plurality of fillers, extenders, and additives, is deposited on the substrate by a curtain coating process, and wherein the catalyst is a basic component.

The method of claim 1 or 2, wherein the liquid mixture is deposited on a substrate selected from the group consisting of metal strips, polymeric strips, fiber sheets and fiber webs.

The method according to any one of claims 1 to 3, wherein the liquid mixture is deposited on a substrate to form a film having a basis weight of 20,500 g / m ² , in particular 80-250 g / m ² , for example 90-150 g / m ² .

The method according to any one of claims 1 to 4, wherein the layer of the liquid mixture is dried at a temperature of 15 to 100 ° C, in particular 20 to 80 ° C, for 1 to 300 minutes.

The method of any one of claims 1 to 5, wherein the dried or drying film is peeled from the substrate to provide binder composition chips having a maximum dimension of 2 to 50 mm.

The method according to any one of claims 1 to 6, wherein the dried film or chips have a solids content of at least 80%, preferably at least 85%, most preferably 85-95% by weight or more.

The method according to any one of claims 1 to 7, wherein the chips are dissolved in water and optionally added at least one component selected from the group consisting of an aldehyde-based resin, formaldehyde, basic substances and mixtures thereof to form a liquid binder.