SE1951516A1 - Process for the preparation of a bonding resin - Google Patents

Abstract

The present invention relates to a process for preparing a bonding resin, wherein lignin is provided in the form of a solution in ammonia and/or an organic base and mixed with one or more crosslinkers and optionally one or more additives. The bonding resin is useful for example in the manufacture of laminates, mineral wool insulation and wood products such as plywood, oriented strandboard (OSB), laminated veneer lumber (LVL), medium density fiberboards (MDF), high density fiberboards (HDF), parquet flooring, curved plywood, veneered particleboards, veneered MDF or particle boards. The bonding resin is also useful for example in composites, molding compounds and foundry applications.

Description

PROCESS FOR THE PREPARATION OF A BONDING RESIN Field of the invention The present invention relates to a process for preparing a bonding resin,wherein lignin is provided in the form of a solution in ammonia and/or anorganic base and mixed with one or more crosslinker selected from glyceroldiglycidyl ether, polyglycerol diglycidyl ether, polyglycerol polyglycidyl ether,glycerol triglycidyl ether, sorbitol polyglycidyl ether, alkoxylated glycerolpolyglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolpropanediglycidyl ether, polyoxypropylene glycol diglycidylether, polyoxypropyleneglycol triglycidyl ether, diglycidylether of cyclohexane dimethanol, resorcinoldiglycidyl ether, isosorbide diglycidyl ether, pentaerythritol tetraglycidyl ether,ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether having 2-9ethylene glycol units, propylene glycol diglycidyl ether having 1-5 propyleneglycol units, diglycidyl-, triglycidyl- or polyglycidyl- ether of a carbohydrate,diglycidyl-, triglycidyl- or polyglycidyl-ester of a carbohydrate, diglycidyl-etheror diglycidyl ester of salicylic acid, vani||ic acid, or 4-hydroxybenzoic acid, anepoxidized or g|ycidy| substituted plant-based phenolic compound (such astannin, cardanol, cardol, anacardic acid) or epoxidized plant-based oil (suchas rapeseed oil, linseed oil, soy bean oil), tris(4-hydroxyphenyl) methanetriglycidyl ether, N,N-bis(2,3-epoxypropyl)aniline, p-(2,3-epoxypropoxy-N,N-bis(2,3-epoxypropyl)aniline, diglycidyl ether of bis-hydroxymethylfuran, and/ordiglycidyl ether of terminal diol having a linear carbon chain of 3-6 carbonatoms, and a crosslinker having functional groups selected from g|ycidy|amine, diglycidyl amine, triglycidyl amine, polyglycidyl amine, g|ycidy| amide,diglycidyl amide, triglycidyl amide, polyglycidyl amide, g|ycidy| ester, diglycidylester, triglycidyl ester, polyglycidyl ester, g|ycidy| azide, diglycidyl azide,triglycidyl azide, polyglycidyl azide, g|ycidy| methacrylate, diglycidylmethacrylate, triglycidyl methacrylate or polyglycidyl methacrylate; andoptionally one or more additives. The bonding resin is useful for example in the manufacture of Iaminates, mineral wool insulation and wood productssuch as plywood, oriented strandboard (OSB), laminated veneer lumber(LVL), medium density fiberboards (MDF), high density fiberboards (HDF),parquet flooring, curved plywood, veneered particleboards, veneered MDF orparticle boards. The bonding resin is also useful for example in composites, molding compounds and foundry applications.

Background Lignin, an aromatic polymer is a major constituent in e.g. wood, being themost abundant carbon source on Earth second only to cellulose. ln recentyears, with development and commercialization of technologies to extractlignin in a highly purified, solid and particularized form from the pulp-makingprocess, it has attracted significant attention as a possible renewablesubstitute to primarily aromatic chemical precursors currently sourced from the petrochemical industry.

Lignin, being a polyaromatic network has been extensively investigated as asuitable substitute for phenol during production of phenol-formaldehydeadhesives. These are used during manufacturing of laminate and structuralwood products such as plywood, oriented strand board and fiberboard. Duringsynthesis of such adhesives, phenol, which may be partially replaced bylignin, is reacted with formaldehyde in the presence of either basic or acidiccatalyst to form a highly cross-linked aromatic resins termed novolacs (whenutilizing acidic catalysts) or resoles (when utilizing basic catalysts). Currently,only limited amounts of the phenol can be replaced by lignin due to the lower reactivity of lignin.

One problem when preparing resins comprising lignin is the use offormaldehyde, when the lignin is used in formaldehyde-containing resins,such as lignin-phenol-formaldehyde resins. Formaldehyde based resins emitformaldehyde, which is a toxic volatile organic compound. The present and proposed Iegislation directed to the Iowering or elimination of formaldehydeemissions have led to the development of formaldehyde free resin for woodadhesive applications.

Jingxian Li R. et al. (Green Chemistry, 2018, 20, 1459-1466) describespreparation of a resin comprising glycerol diglycidyl ether and lignin, whereinthe lignin is provided in solid form. One problem with the technologydescribed in the article is a long pressing time and high pressing temperature.The 3 plies plywood sample was pressed at 150°C temperature for 15 minutes to fully cure the resins.

Engelmann G. and Ganster J. (Holzforschung, 2014, 68, 435-446) describespreparation of a biobased epoxy resin with low molecular weight kraft ligninand pyrogallol, wherein the lignin component consists of an acetoneextraction from Kraft lignin.

Summary of the invention lt has now surprisingly been found that it is possible to easily prepare abonding resin in which the use of formaldehyde can be avoided. lt has alsobeen found that an improved bonding resin can be achieved by providinglignin in the form of an aqueous solution comprising ammonia and/or anorganic base. By providing the lignin in the form of an aqueous solutioncomprising ammonia and/or an organic base, the step of milling of ligninparticles can be avoided, avoiding lignin lump formation and the use ofdispersing agent. lt has been found that when lignin is provided in form of an aqueous solutioncomprising ammonia and/or organic base, the phenolic hydroxyl groups in thelignin structure are deprotonated and free to react with the epoxide groups.This improves the reactivity and performance of the binder. Therefore, providing the lignin in the form of a an aqueous solution comprising ammonia and/or an organic base speeds up the reaction significantly and hencereduces the pressing time and enables the use of a lower pressingtemperature for curing the bonding resin, when manufacturing for examplelaminates, mineral wool insulation and wood products such as piywood,oriented strandboard (OSB), laminated veneer lumber (LVL), medium densityfiberboards (MDF), high density fiberboards (HDF), parquet flooring, curvedplywood, veneered particleboards, veneered MDF or particle boards. Thebonding resin is also useful for example in composites, molding compounds and foundry applications.

Furthermore, by providing lignin in the form an aqueous solution of lignincomprising ammonia and/or an organic base the risk of degrading for example glass wool and mineral wool fibers is minimized.

The present invention is thus directed to a method for preparing a bondingresin, wherein an aqueous solution of lignin comprising ammonia and/or anorganic base is mixed with one or more crosslinker selected from glyceroldiglycidyl ether, polyglycerol diglycidyl ether, polyglycerol polyglycidyl ether,glycerol triglycidyl ether, sorbitol polyglycidyl ether, alkoxylated glycerolpolyglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolpropanediglycidyl ether, polyoxypropylene glycol diglycidylether, polyoxypropyleneglycol triglycidyl ether, diglycidylether of cyclohexane dimethanol, resorcinoldiglycidyl ether, isosorbide diglycidyl ether, pentaerythritol tetraglycidyl ether,ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether having 2-9ethylene glycol units, propylene glycol diglycidyl ether having 1-5 propyleneglycol units, diglycidyl-, triglycidyl- or polyglycidyl- ether of a carbohydrate,diglycidyl-, triglycidyl- or polyglycidyl-ester of a carbohydrate, diglycidyl-etheror diglycidyl ester of salicylic acid, vanillic acid, or 4-hydroxybenzoic acid, anepoxidized or glycidyl substituted plant-based phenolic compound (such astannin, cardanol, cardol, anacardic acid) or epoxidized plant-based oil (suchas rapeseed oil, linseed oil, soy bean oil), tris(4-hydroxyphenyl) methanetriglycidyl ether, N,N-bis(2,3-epoxypropyl)aniline, p-(2,3-epoxypropoxy-N,N-bis(2,3-epoxypropyl)aniline, diglycidyl ether of bis-hydroxymethylfuran, and/or diglycidyl ether of terminal diol having a linear carbon chain of 3-6 carbonatoms, and a crosslinker having functional groups selected from glycidylamine, diglycidyl amine, triglycidyl amine, polyglycidyl amine, glycidyl amide,diglycidyl amide, triglycidyl amide, polyglycidyl amide, glycidyl ester, diglycidylester, triglycidyl ester, polyglycidyl ester, glycidyl azide, diglycidyl azide,triglycidyl azide, polyglycidyl azide, glycidyl methacrylate, diglycidylmethacrylate, triglycidyl methacrylate, or polyglycidyl methacrylate.

One aspect of the present invention is a method for preparing a bondingresin, wherein an aqueous solution of |ignin comprising ammonia and/or anorganic base is mixed with one or more cross-Iinkers and/or one or moreglycidyl ethers, wherein the cross-linker has an epoxy index above 4 eq/kg.The epoxy index can be determined according to ISO 3001. Preferably, thecross-linker has an epoxy index above 5 eq/kg. The cross-linker is analiphatic or, preferably, aromatic glycidyl ether. Preferably, the cross-linker isaliphatic.

The glycidyl ethers may be polyfunctional epoxides and the method accordingto the present invention may use a mixture of epoxides, such as monofunctionai, di-functional, tri-functional and/or tetra-functional.

The present invention is thus also directed to the bonding resin obtainableusing the method described herein and to the use of the bonding resin in themanufacture of laminates, mineral wool insulation and wood products such asplywood, oriented strandboard (OSB), laminated veneer lumber (LVL),medium density fiberboards (MDF), high density fiberboards (HDF), parquetflooring, curved plywood, veneered particleboards, veneered MDF or particleboards. The present invention is also directed to such laminates, mineral woolinsulation and wood products such as plywood, oriented strandboard (OSB),laminated veneer lumber (LVL), medium density fiberboards (MDF), highdensity fiberboards (HDF), parquet flooring, curved plywood, veneeredparticleboards, veneered MDF or particle boards manufactured using the bonding resin. The bonding resin according to the present invention may also be used in the manufacture of composites, molding compounds and foundry applications.

Detailed description lt is intended throughout the present description that the expression "lignin"embraces any kind of lignin, e.g. lignin originated from hardwood, softvvood orannu|ar p|ants. Preferably the lignin is an a|ka|ine lignin generated in e.g. theKraft process. Preferably, the lignin has been purified or isolated before beingused in the process according to the present invention. The lignin may beisolated from black liquor and optionally be further purified before being usedin the process according to the present invention. The purification is typicallysuch that the purity of the lignin is at least 90%, preferably at least 95%. Thus,the lignin used according to the method of the present invention preferablycontains less than 10%, preferably less than 5% impurities. The lignin maythen be separated from the black liquor by using the process disclosed inWO2006031175. The lignin may then be separated from the black liquor byusing the process referred to as the LignoBoost process. The lignin may beprovided in the form of particles, such as particles having an average particlesize of from 50 micrometers to 500 micrometers.

The glycerol diglycidyl ether, polyglycerol diglycidyl ether, polyglycerolpolyglycidyl ether, glycerol triglycidyl ether, sorbitol polyglycidyl ether,alkoxylated glycerol polyglycidyl ether, trimethylolpropane triglycidyl ether,trimethylolpropane diglycidyl ether, polyoxypropylene glycol diglycidylether,polyoxypropylene glycol triglycidyl ether, diglycidylether of cyclohexanedimethanol, resorcinol diglycidyl ether, isosorbide diglycidyl ether,pentaerythritol tetraglycidyl ether, ethylene glycol diglycidyl ether,polyethylene glycol diglycidyl ether having 2-9 ethylene glycol units,propylene glycol diglycidyl ether having 1-5 propylene glycol units, diglycidyl-,triglycidyl- or polyglycidyl- ether of a carbohydrate, diglycidyl-, triglycidyl- or polyglycidyl-ester of a carbohydrate, diglycidyl-ether or diglycidyl ester ofsalicylic acid, vanillic acid, or 4-hydroxybenzoic acid, an epoxidized orglycidyl substituted plant-based phenolic compound (such as tannin,cardanol, cardol, anacardic acid) or epoxidized plant-based oil (such asrapeseed oil, linseed oil, soy bean oil), tris(4-hydroxyphenyl) methanetriglycidyl ether, N,N-bis(2,3-epoxypropyl)aniline, p-(2,3-epoxypropoxy-N,N-bis(2,3-epoxypropyl)aniline, diglycidyl ether of bis-hydroxymethylfuran, and/ordiglycidyl ether of terminal diol having a linear carbon chain of 3-6 carbonatoms, and a crosslinker having functional groups selected from glycidylamine, diglycidyl amine, triglycidyl amine, polyglycidyl amine, glycidyl amide,diglycidyl amide, triglycidyl amide, polyglycidyl amide, glycidyl ester, diglycidylester, triglycidyl ester, polyglycidyl ester, glycidyl azide, diglycidyl azide,triglycidyl azide, polyglycidyl azide, glycidyl methacrylate, diglycidylmethacrylate, triglycidyl methacrylate, or polyglycidyl methacrylate usedaccording to the present invention acts as a cross-linker. Glycidyl ethers withmore functional epoxide groups can be used such as glycerol diglycidyl ether,glycerol triglycidyl ether and sorbitol polyglycidyl ether. Other glycidyl ethershaving two to nine alkylene glycol groups (such as 2-4 alkylene glycol groupsor 2-6 alkylene glycol groups) can be used, such as diethylene glycoldiglycidyl ether, triethylene glycol diglycidyl ether, dipropylene glycol diglycidylether and tripropylene diglycidyl ether. As the chain lengths between twoglycidyl ether groups gets longer, the resin becomes more flexible, which maynegatively influence its performance. lt results in an adhesive during curing.Other suitable crosslinkers include crosslinkers having functional groupsselected from glycidyl amine, diglycidyl amine, triglycidyl amine, polyglycidylamine, glycidyl amide, diglycidyl amide, triglycidyl amide, polyglycidyl amide,glycidyl ester, diglycidyl ester, triglycidyl ester, polyglycidyl ester, glycidylazide, diglycidyl azide, triglycidyl azide, polyglycidyl azide, glycidylmethacrylate, diglycidyl methacrylate, triglycidyl methacrylate and polyglycidylmethacrylate. Typically, the bonding resin according to the present inventionis and applied to the surfaces of for example veneers, such as in themanufacture of plywood. When the veneers are pressed together under heating, the cross-linking in the bonding resin takes place, resulting in anadhesive.

An aqueous solution of lignin comprising ammonia and/or an organic basecan be prepared by methods known in the art, such as by mixing lignin andammonia and/or organic base with water. The pH of the aqueous solution oflignin comprising ammonia and/or an organic base is preferably in the rangeof from 10 to 14. Examples of organic bases include amines, such as primary,secondary and tertiary amines and mixtures thereof. Preferably, the organicbase is selected from the group consisting of methylamine, ethylamine,propylamine, butylamine, ethylenediamine, methanolamine, ethanolamine,aniline, cyclohexylamine, benzylamine, dimethylamine, diethylamine,dipropylamine, dibutylamine, dimethanolamine, diethanolamine,diphenylamine, phenylmethylamine, phenylethylamine, dicyclohexylamine,piperazine, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, 2- phenylimidazole, 2-methylimidazoline, 2-phenylimidazoline, trimethylamine, triethylamine,dimethylhexylamine, N-methylpiperazine, dimethylbenzylamine, aminomethylpropanol, tris(dimethylaminomethyl)phenol and dimethylaniline or mixturesthereof. The total amount of ammonia and/or organic base in the aqueoussolution is preferably in the range of from 0.1 wt-% to 20 wt-%, preferably 0.1wt-% to 10 wt-%, of the total weight of the aqueous solution comprising water,lignin and ammonia and/or an organic base. The amount of lignin in theaqueous solution of lignin comprising ammonia and/or an organic base ispreferably from 1 vvt-% to 60 wt-% of the solution, such as from 10 vvt-% to 30vvt-% of the solution. The aqueous solution of lignin comprising ammoniaand/or an organic base does not comprise alkali.

The weight ratio between lignin (dry weight) and the total amount ofcrosslinker is preferably in the range of from 1:10 to 10:1. The amount oflignin in the bonding resin is preferably from 5 wt-% to 50 vvt-%, calculated as the dry weight of lignin and the total weight of the bonding resin.

The bonding resin may also comprise additives, such as urea, tannin,surfactants, dispersing agents and fillers.

The amount of urea in the bonding resin can be 0-40% preferably 5-20%calculated as the dry weight of urea and the total weight of the bonding resin.

A filler and/or hardener can also be added to the bonding resin. Examples ofsuch fillers and/or hardeners include limestone, cellulose, sodium carbonate,and starch.

The reactivity of the lignin with the glycidyl ether can be increased bymodifying the lignin by glyoxylation, etherification, esterification or any othermethod where lignin hydroxyl content or carboxylic content or amine content or thiol content is increased.

The aqueous solution of lignin comprising ammonia and/or an organic base ispreferably mixed with the glycidyl ether at room temperature, such as at atemperature of from 15°C to 30°C. The mixing is preferably carried out forabout 5 seconds to 2 hours. Preferably, the viscosity of the mixture ismonitored during mixing, either continuously or by taking samples and determining the viscosity thereof. ln the production of mineral wool insulation, curing of the bonding resin toform an adhesive takes place when the components used for the preparation of the mineral wool insulation are exposed to heating.

Examples Example 1 Lignin solution was prepared first by adding 243 g of powder lignin (solidcontent 95%) and 619 g of water were added to a 1 L glass reactor atambient temperature and were stirred until the lignin was fully and evenly dispersed. Then, 138 g of 28-30% ammonia solution was added to the lignin dispersion. The composition was stirred for 60 minutes to make sure that thelignin was completely dissolved.

Example 23-Aminopropyl trimethoxysilane was diluted to 1% solution in water. Binder composition was prepared by weighing 31.2 g of lignin-ammonia solution fromthe example 1, 7.8 g of polyglycerol polyglycidyl ether and 3 g of 1% of 3-Aminopropyl trimethoxysilane into a 250ml plastic container and was stirredwith a wooden stick for 2 minutes. Silica sand was weighed into a bowl andthe lignin mixture were poured on top of the sand and mixed with an electrichand mixer for 2 minutes. Then, the sand bars were prepared by putting thesand-binder mixture into a mould for baking in an oven at 200°C for 2 hours.All sand bars were hard and stable after curing in the oven. The size of thebar for each test is height x thickness x length: 23mm x 22mm x 84mm.

Sand bars were conditioned in a water bath at 80°C for 2 hours. Sand barswere post-cured for 24 hours and soaked in a water bath at 80°C for 2 hours.The sand bars were evaluated with 3 point bending test. The flexural strengthbefore and after water soaking is given in the Table 1.

Example 3 Binder composition was prepared by weighing 37.8 g of lignin-ammoniasolution from the example 1, 7.6 g of polyglycerol polyglycidyl ether and 3 g of1% of 3-aminopropyl trimethoxysilane into a 250ml plastic container and wasstirred with a wooden stick for 2 minutes. Silica sand was weighed in to abowl and the lignin mixture were poured on top of the sand and mixed with anelectric hand mixer for 2 minutes. Then, the sand bars were prepared byputting the sand-binder mixture into a mould for baking in an oven at 180°Cfor 2 hours. All sand bars were hard and stable after curing in the oven.

Sand bars were conditioned in a water bath at 80°C for 2 hours. Sand barswere post-cured for 24 hours and then soaked in a water bath at 80°C for 2hours. The sand bars were evaluated with 3 point bending test. The flexuralstrength before and after water soaking is given in the Table 1. 11 Flexural Strength without conditioning Flexural Strength after conditioning Example 3 [MPa] [MPa]Sand bars from the 8.8 3.0Example 2Sand bars from the 7.1 2.5 Table 1. Flexural Strength of the sand bars with and without conditioning ln view of the above detailed description of the present invention, other modifications and variations will become apparent to those skilled in the art.

However, it should be apparent that such other modifications and variations may be effected without departing from the spirit and scope of the invention.

Claims (1)

1. 1. Claims 12 A method for preparing a bonding resin, wherein an aqueoussolution of lignin comprising ammonia and/or an organic base ismixed with one or more crosslinker selected from glyceroldiglycidyl ether, polyglycerol diglycidyl ether, polyglycerolpolyglycidyl ether, glycerol triglycidyl ether, sorbitol polyglycidylether, aikoxyiated glycerol polyglycidyl ether, trimethyioipropanetriglycidyl ether, trimethyioipropane diglycidyl ether,polyoxypropyiene glycol diglycidylether, polyoxypropyiene glycoltriglycidyl ether, diglycidylether of cyclohexane dimethanol,resorcinol diglycidyl ether, isosorbide diglycidyl ether,pentaerythritol tetraglycidyi ether, ethyiene glycol diglycidyl ether,poiyethyiene glycol diglycidyl ether having 2-9 ethylene glycolunits, propyiene glycol diglycidyl ether having 1-5 propyieneglycol units, diglycidyl-, triglycidyl- or polyglycidyl- ether of acarbohydrate, diglycidyl-, triglycidyl- or polyglycidyl-ester of acarbohydrate, diglycidyl-ether or diglycidyl ester of salicylic acid,vani||ic acid, or 4-hydroxybenzoic acid, an epoxidized or g|ycidy|substituted plant-based phenolic compound or epoxidized plant-based oil, tris(4-hydroxyphenyl) methane triglycidyl ether, N,N-bis(2,3-epoxypropyl)aniline, p-(2,3-epoxypropoxy-N,N-bis(2,3-epoxypropyl)aniline, diglycidyl ether of bis-hydroxymethylfuran,and/or diglycidyl ether of terminal diol having a linear carbonchain of 3-6 carbon atoms, and a crosslinker having functionalgroups selected from g|ycidy| amine, diglycidyl amine, triglycidylamine, polyglycidyl amine, g|ycidy| amide, diglycidyl amide,triglycidyl amide, polyglycidyl amide, g|ycidy| ester, diglycidylester, triglycidyl ester, polyglycidyl ester, g|ycidy| azide, diglycidylazide, triglycidyl azide, polyglycidyl azide, g|ycidy| methacrylate,diglycidyl methacrylate, triglycidyl methacrylate, or polyglycidylmethacrylate; and optionally one or more additives. A method according to claim 1, wherein the crosslinker ispolyglycerol polyglycidyl ether. 10. 13 A method according to claim 1 or 2, wherein the aqueous solutionof lignin comprising ammonia and/or an organic base comprisesat least 5% by weight of lignin. A method according to any one of claims 1-3, wherein the weightratio between lignin, calculated on the basis ofdry lignin, and thetotal amount of crosslinker is from 1:10 to 10:1. A method according to any one of claims 1-4, wherein theadditive is urea, tannin, surfactant, dispersing agent, and/or afiller. A method according to any one of claims 1-5, wherein the lignin ismodified by glyoxylation, etherification, esterification or any othermethod where lignin hydroxyl content or amine content or thiolcontent is increased. A method for preparing a bonding resin, wherein an aqueoussolution of lignin comprising ammonia and/or an organic base ismixed with one or more cross-linkers and/or one or more glycidylethers, wherein the cross-linker has an epoxy index above 4eq/kg. A bonding resin obtainable by the method of any one of claims 1-7. Use of a bonding resin according to claim 8 in the manufacture ofa laminate, mineral wool insulation, wood product such asplywood, oriented strandboard (OSB), laminated veneer lumber(LVL), medium density fiberboards (MDF), high densityfiberboards (HDF), parquet flooring, curved plywood, veneeredparticleboards, veneered MDF or particle boards. Use of a bonding resin according to claim 8, wherein the bondingresin is provided to a surface in the preparation of a laminate,mineral wool insulation, wood product such as plywood, orientedstrandboard (OSB), laminated veneer lumber (LVL), mediumdensity fiberboards (MDF), high density fiberboards (HDF),parquet flooring, curved plywood, veneered particleboards, 11. 14 veneered MDF or particle boards, and wherein curing of thebonding resin to form an adhesive takes place when the surfaceis exposed to pressure and heating. Laminate, mineral wool insulation, wood product such asplywood, oriented strandboard (OSB), Iaminated veneer Iumber(LVL), medium density fiberboards (MDF), high densityfiberboards (HDF), parquet flooring, curved plywood, veneeredparticleboards, veneered MDF or particle boards manufacturedusing a bonding resin according to c|aim 10.