WO2024218102A1 - Modification of aromatic polymers - Google Patents

Abstract

The invention is directed to modified articles, objects or bodies M based on oligomeric or polymeric phenolic materials K, where diazonium, compounds B carrying at least one further functional group which is hydrophilic or hydrophobic, or alters the surface tension or of the resins so modified, are coupled to the said phenolic materials K via an azo coupling reaction. The oligomeric or polymeric phenolic materials K are selected, from the group consisting of novolaks N, resoles R, and polymers P particularly including lignin L and tannin T, having aromatic moieties with increased electron density in comparison with benzene at unsubstituted carbon atoms in the said aromatic moiety. The diazonium group-containing modifiers B are aromatic compounds having a diazonium group of formula - (I), and at least one further functional group which is hydrophilic or hydrophobic, or otherwise influences the cohesion and adhesion properties of the resins so modified, such as perfluoroalkyl groups or oligo- and poly-siloxane groups.

Description

Modification of Aromatic Polymers

Field of the Invention

This invention is directed to method for modification of articles or bodies made from aromatic polymers K by treatment thereof with non-polymeric aromatic diazonium compounds B via azo coupling to obtain a modified article or body M. The invention is also directed to such modified articles or bodies M. It is also directed to methods of use of modified articles or bodies M.

Background of the Invention

Aromatic diazonium compounds, also referred to simply as "diazonium compounds" in the context of this invention, have been commercially used in the preparation of azo dyes where the so-called "azo coupling" occurs, i. e., an electrophilic substitution reaction of an aromatic diazonium compound

with a nucleophilic molecule, usually an aromatic compound that preferably has an increased electron density at carbon atoms of its aromatic ring compared to an unsubstituted aromatic molecule, due to electron-donating substituents (also referred to as "activating groups"which replace a hydrogen atom connected to a carbon atom which is a part of the aromatic system, such as hydroxyl groups, amino groups, alkoxy groups, alkylamino groups, dialkylamino groups, and alkyl groups. The nucleophilic molecules are therefore preferably phenols, aminophenols, alkoxy aromatics, (di)alkylamino- aromatics, and alkylaromatics, and particularly preferred, alkyl phenols and alkoxy phenols. This effect has been described in detail, e. g., in Peter Sykes "Reaktionsmechanismen in der organischen Chemie", 3rd edition, Weinheim 1967, pages 131 to 135, and Peter Sykes, "Guidebook to Mechanism in Organic Chemistry", 6th edition New York 1985. Electron- withdrawing groups as substituents in an aromatic compound such as -NO₂, -SO₃H, -C(H)O, -COOH, -CN are also referred to as "deactivating groups", and lead to slower reaction rates, due to the lower electron density in comparison to the unsubstituted aromatic compound. The change in electron density at the carbon atoms in ortho-, meta-, or para-position to the substituent in an aromatic compound, e. g., in the monosubstituted benzene N,N- dimethylaniline where the substituent is - N(CH₃)₂, can be measured by the difference Δδ = δ_H,i- δ_{H, unsubstituted} in the chemical shift in a proton NMR spectrum δ_H,i of a H atom in an aromatic compound where i stands for any one position of ortho, meta, and para, between the values δ_{H,orth o} , δ_H,meta , and δ_{H, para} , for the residual H atoms in the monosubstituted benzene, and the value δ_{H unsubstituted} of the H atoms in unsubstituted benzene, in this case: δ_{H,orth o} = -0.6 ppm, δ_H,meta = - 0.1 ppm, and δ_{H, para} = - 0.62 ppm. See, e. g„ the publication "Chemical Shifts" issued by the University College of London, Lecture Notes, "https://www.ucl.ac.uk/nmr/lecture- notes", last modified 07 April 2024.

In the patent US 3,274,166 A, a process of modifying a hydrocarbon polymer has been dis- closed which comprises heating said hydrocarbon polymer in admixture with a polymer of a poly(diazo) compound selected from the group consisting of

, and where x is an integer of from 2 to 4, R is an

organic group inert to -modifications, A is an aromatic group inert to modifications, R' is selected from the group consisting of H, alkyl, aryl, and C(O)OZ groups, where Z is an alkyl or aryl group, and R" is selected from the group consisting of H, alkyl and aryl radicals, said heating being at the decomposition temperature of said poly(diazo) compound whereby chemical bonding is effected between the polymer molecules. Examples of these poly(diazo) compounds are the bis(diazoacetate) ester of 1,6-hexanediol, the bis (diazoacetate) ester of 1,10-decanediol, the tetra (diazoacetate) ester of pentaerythritol, and the bis(diazoacetate) ester of diethylene glycol. As mentioned in this document, it is believed that the poly(diazo) compounds react by eliminating nitrogen, leaving a carbene group at each end of the molecule. These free carbene groups then react with the hydrocarbon polymer and act as crosslinkers.

In the patent US 3,276,064 A, polymeric azo dyes are described which are prepared in a three- step process (see paragraphs 3 and 4 in page one, starting with the words "It has been found ...", and "By the practice ..."), where in the first step, a novolac polymer is prepared from phenol and an aldehyde or ketone; in the second step, this novolac polymer (referred to herein as the "resin progenitor" in paragraph 3 of page one) is coupled with a diazonium salt to provide an "intermediate polymer"; and in the third step, "this intermediate polymer is then caused to crosslink with itself or other reactive polymers so that the cured polymer is itself a dye rather than a mechanical mixture with a dispersed conventional dye". The "coloured resinous materials [are] useful as components of inks, solid bodies and coating compositions", see paragraph 1 of page 1. No reaction of a diazonium salt with a surface of a pre-formed polymer is disclosed which does not require a subsequent crosslinking reaction.

In the patent application WO 2004/035310 Al, a heat-sensitive lithographic printing-plate precursor is described which comprises a support having a hydrophilic surface and an oleophilic coating, provided on the hydrophilic surface, said coating comprising an infrared light absorbing agent and a polymer which comprises a phenolic monomeric unit wherein the phenyl group of the phenolic monomeric unit is substituted by a group having the structure -N=N-Q, wherein the -N=N- group is covalently bound to a carbon atom of the phenyl group and wherein Q is an aromatic group. As the coating is prepared from a solution of the polymer together with solvents, dyes, slip and anti-crater additives, see page 43, "Preparation of the Coating", lines 7 et seq., the polymer is distributed homogeneously on the support. No reaction of a diazonium salt with a surface of a pre-formed polymer is disclosed.

In the patent application US 2023/0058483 Al, hereinafter referred to as "the '483 document", a hydroponic growth medium is disclosed which comprises a hemp fiber biocomposite comprising lignin-containing hemp fibers crosslinked by a polymer. See claim 1 on page 23 of the '483 document. A diazonium salt formed in step (a) from an aromatic amine having a protected vinyl sulfone group is coupled in step (b) to a lignin molecule of a lignin-containing plant fibre, and the vinyl sulfone functionalised fibre is deprotected in step (c) under basic conditions in the presence of a polymer, thus forming a crosslinked product. See paragraph [0010], Biocomposites are formed, according to paragraph [0006], which comprise lignin- containing plant fibres (such as hemp fibres) which are crosslinked by one or more polymers, e. g. polyvinyl alcohol (PVA). The polymers mentioned in the ’483 document additionally include pectin (see paragraph [0006] in page 1, right-hand column, fourth line from the top), and "any appropriate polymer" (paragraph [0056], lines 4 and 5), which may be "a molecule of repeating structural units ... formed via a chemical reaction, i. e. polymerisation", and may, in some cases be a water-soluble polymer, a natural or synthetic polymer, a biodegradable polymer, or a biocompatible polymer, which can include one or more hydroxyl groups (see paragraph [0056], lines 7 to 12. Examples include PVA, pectin, starch, cellulose, and any combinations thereof, see lines 15 and 16 of paragraph [0056]. The crosslinking reaction is obviously a reaction between the vinylsulfone group bound to the aryl part of the "bifunctional linker" and the hydroxyl groups of the polymer under basic conditions which leads to the formation of a sulfonic ester group which binds to the lignin molecule via an azobenzene structure, and vinyl alcohol which is immediately converted to acetaldehyde. No reactive group is then left on the lignin part of the crosslinked plant fibre. Therefore, no functional group is left on the surface of a plant fibre after a treatment according to the '483 document.

There has not yet been mention of the use of non-polymeric diazonium compounds B which are free from alkyl- or arylsulfone substituents and have either no further substituents on the aromatic ring(s), or have also functional groups F which are not diazonium groups of formula

bound to an aromatic carbon atom, bound to its aromatic ring(s), as reactants in an azo coupling, under incorporation of the diazo group, with aromatic polymers K to modify the reactivity, solubility, electric or dielectric properties, surface or phase interface properties of the surface of such modified aromatic polymers M. An "other functional group" in the context of this invention is any atom or group which is different from a hydrogen group, H-.

Object of the Invention

The object of the invention is to provide a means to modify the surface of aromatic polymers K or of articles and bodies made therefrom, to obtain an object or article M having surface properties differing from those of articles made of the unmodified aromatic polymer K, with respect to mechanical or chemical properties, surface tension in contact with liquids, adhesive and electric or dielectric properties. Aromatic polymers K are selected from the group consisting of resinous oligomeric or polymeric phenolic materials, including phenolic resins PF which are derived from phenols and aldehydes, preferably formaldehyde, or modified phenolic resins MPF which have been modified by incorporation of naturally occurring phenolic bodies such as lignin, and tannin, either as addition thereof to the phenol component to the resinification process, in their native form, or at least partly depolymerised by the commercial processes to isolate these materials, or as preformed condensation products with aldehydes to resins made from the commonly used starting materials, viz., phenol and derivatives thereof including alkylphenols such as cresols, xylenols, nonylphenols, and long chain-alkyl substituted phenols isolated from cashew nutshell oil. These latter are mixtures comprising, as main components, cardanol, cardol and methylcardol; they carry up to three olefinic unsaturations, and can be easily hydrogenated to yield 3-n-pentadecylphenoI, 5-n-pentadecylresorcinol, and 2-methyl-5-n- pentadecylresorcinol. Aromatic polymers K also include natural polymers, particularly lignocellulosic materials, such as wood, grass, plant fibers, also in particulate form, and lignin which has been obtained by separation of cellulose and hemicellulose from the lignocellulosic materials, or by fractionation of lignin isolated from natural feedstocks by any of the known processes. Further aromatic polymers include tannins.

The properties of these aromatic polymers K are largely determined by their composition, i. e., by the kind and the amount of starting materials (educts) used for their synthesis. It is an object of the invention to provide a possibility to modify these properties on the surface of objects, articles and bodies made therefrom, such as reactivity, solubility, interfacial properties such as surface tension, emissions of residual monomers, optical, electrical, chemical and mechanical properties, without a substantial change of the kind and the amount of starting educts. It is possible, according to the invention, to retain favourable mechanical or chemical properties of the aromatic polymers so modified by applying the modifying compound, viz., the aromatic diazonium compounds B, to the surface of ready-made aromatic resins or polymers K.

Summary of the Invention The invention is therefore directed to the modification of surfaces of articles, items or bodies made from aromatic polymer materials K by treating the surface of any of these articles, items or bodies with non-polymeric aromatic diazonium compounds B, wherein aromatic diazonium compounds B having a diazonium group of formula

N bound to an aromatic carbon atom are coupled to the said aromatic polymers K via an azo coupling reaction, which diazonium compounds B do not comprise vinylsulfone structures and either carry no additional substituent in their aromatic structure, or preferably carry at least one further functional group F which is capable of modifying the reactivity, solubility, interfacial properties such as surface tension, adsorption, optical, electrical, chemical and mechanical properties, of the surface of an article, object or body made from the aromatic polymers K to obtain an article, object or body M with such changed surface properties.

The polymeric aromatic materials K are preferably selected from the group consisting of novolaks N, resoles R, and polymers P particularly based on reaction products of aldehydes as detailed infra, with lignin L, and tannin T, which aromatic polymer materials K also include novolaks and resoles where at least a part of the phenols is replaced by lignin or tannin or other naturally occurring substituted phenols, or a mixture thereof, having aromatic moieties with increased electron density in comparison with benzene at unsubstituted carbon atoms in the said aromatic moiety. The polymeric aromatic materials K also comprise natural materials such as wood, or processed wood, including logs, disks, lumber, veneer, strand, chips, wood wool ("Excelsior"), particles, fibre bundles, refined fibre and wood flour, according to the classification of Marra 1972 (cited from "Holzwerkstoffe der Modeme", M. Paulitsch 1998), and fibrous lignocellulosic materials from other plants.

As is known to a person skilled in the art, the increase or decrease in electron density in any aromatic system which is due to a first substituent can be measured by the dipole moment of a singly substituted aromatic compound in comparison to the unsubstituted aromatic compound, or by comparison of the reaction rate of a singly substituted aromatic compound and that of the corresponding unsubstituted aromatic compound in an electrophilic reaction with the same electrophilic compound, such as in the nitration of an aromatic compound by a cation, see, e. g., Peter Sykes, "A Guidebook to Mechanism in Organic Chemistry",

Chapter 6: "Electrophilic and Nucleophilic Substitution in Aromatic Systems; 6.7: "Electrophilic Attack on C₆H₅Y", et seq., 6th edition, New York 1985.

It has been found in the experiments which have led to the present invention that the azo coupling of non-polymeric diazonium group-containing modifiers B which are free from vinylsulfone structural units, and are aromatic compounds having a diazonium group of formula , and preferably at least one further functional group F as detailed infra with

resinous oligomeric or polymeric phenolic materials K leads to modified resins M where the degree of modification relative to the unmodified resin K can be tailored by varying the ratio m_B / m_K of the mass m_B of the said diazonium group-containing modifiers B to the mass m_K of the unmodified resin K in the diazo coupling reaction, and by varying the nature of the diazonium group-containing modifiers B.

Detailed Description of the Preferred Embodiments

The diazonium group-containing modifiers B are aromatic compounds which are non- polymeric and do not contain a vinylsulfone structure within their molecule, and having: a diazonium group of formula

, and either no additional group, or preferably, at least one further functional group F which is selected from the group consisting of hydroxyl groups-OH, linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkoxy groups -O-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkoxycarboxy groups -C(O)-O-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkylcarbonyl groups -C(O)-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; aryl groups having from five to twenty carbon atoms; heteroaryl groups having from two to twenty carbon atoms and at least one hetero atom which is selected from the group consisting of oxygen -O- groups, sulphur -S- groups, and nitrogen, in the form of - N = groups or imine -N(H)- groups, where, in the case of two or more hetero atoms, these heteroatoms or heteroatom-containing groups, may be the same, or may be different from each other; alkylamino groups and dialkylamino groups , where R_N1 and R_N2

may be the same, or may be different from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; aldehyde groups -C(O)-H; phosphate -O-P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; phosphonate -P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; carboxylic acid groups -C(O) - OH; sulphonic acid groups -S(O₂) - OH; phosphonic acid groups -P(O)(OH)₂; cyanate -O-C=N groups; nitro -NO₂ groups; thiol -SH groups; halogen -F, -Cl, -Br, -I groups; cyano (=nitrile) -C≡N groups; aldehyde -C(O)-H groups; (per)fluoroalkyl groups; oligo-siloxane groups; and poly-siloxane groups. Depending on their chemical nature, these groups are hydrophilic or hydrophobic, and add a further functionality to the diazonium group-containing modifiers B, and thus change the physico- chemical properties of the surface of the article, item or object M so modified, e. g., hydrophilicity or hydrophobicity, phase interface properties such as sorption, surface properties, cohesion and adhesion properties, solubility, light and chemical resistance, and chemical reactivity.

The simplest modifier B which has no further reactive group is made by diazotisation of aniline, under formation of a molecule of the structure

, where

is the anion of the acid present in the formation of a diazonium salt B derived from aniline.

Preferred modifiers B are made from primary aromatic monoamines having further acid functional groups, particularly, sulphonic acid groups, carboxylic acid groups, and phos- phonic acid groups which render the article, item or object M modified therewith more hydrophilic. The modifiers B that increase the hydrophilicity are preferably selected from the group consisting of ortho-, meta-, and para- aminobenzene sulphonic acids, naphthalene- sulphonic acids further comprising at least one hydroxyl group and/or at least one amino group, together also known as "Buchstabensauren" which are additionally substituted amino- naphthalene sulphonic acids including Cleve β-acid (5-aminonaphthalene-2-sulphonic acid), Cleve γ-acid (4-aminonaphthalene-2-sulphonic acid), naphthionic acid (1-aminonaphthalene- 4-sulphonic acid), Laurent acid, also known as purpurinic acid (l-aminonaphthalene-5- sulphonic acid), 1,7-Cleve acid (6-aminonaphthalene-2-sulphonic acid), peri acid (1- aminonaphthalene-8-sulphonic acid), Tobias acid, also known as A acid (2-aminonaphthalene- 1-sulphonic acid), Dahl acid I (2-aminonaphthalene-5-sulphonic acid), Cassella F acid (2- aminonaphthalene-7-sulphonic acid), Bronner acid (2-aminonaphthalene-6-sulphonic acid), Erdmann acid (2-aminonaphthalene-7-sulphonic acid), and aminocroceine acid (2-aminonaph- thalene-8-sulphonic acid), aminonaphthalene disulphonic acids including Kalle acid (1- aminonaphthalene-3,6-disulphonic acid), Freund acids II and III (l-aminonaphthalene-3,6- disulphonic acid and l-aminonaphthalene-3,7-disulphonic acid), amino epsilon acid (1- aminonaphfhalene-3,8-disulphonic acid), Dahl acids II and in (l-aminonaphthalene-4,6- disulphonic acid and l-aminonaphthalene-4,7-disulphonic acid), C acid (2-aminonaphthalene- 4,8-disulphonic acid), amino G acid (2-aminonaphthalene-5,8-disulphonic acid), and further, the hydroxyaminosulphonic acids referred to as Boninger acid (l-aminonaphthalene-2- hydroxy-4-sulphonic acid), M acid (8-amino-4-hydroxynaphthalene-2-sulphonic acid), I acid (7-amino-4-hydroxynaphthalene-2-sulphonic acid), Sulfo-I acid (2-amino-5-hydroxynaphtha- lene-l,7-disulphonic acid), y acid (6-amino-4-hydroxynaphthalene-2-sulphonic acid), RR acid (3-amino-5-hydroxynaphthalene-2,7-disulphonic acid), S acid (4-amino-5-hydroxynaphtha- lene-l-sulphonic acid), K acid (4-amino-5-hydroxynaphthalene-l-sulphonic acid), H acid (4- amino-5-hydroxynaphthalene-2,7-disulphonic acid), SS acid, also known as Chicago SS acid (4-amino-5-hydroxynaphthalene-l,3-disulphonic acid), and the aminotrisulphonic acid "Koch acid" (l-aminonaphthalene-3,6,8-trisulphonic acid).

Enhanced reactivity, particularly in the diazo coupling with a lignin L, can be realised by using modifiers B that introduce reactive sites, such as diazonium group-containing modifiers having an aromatic nucleus with addition phenolic hydroxyl groups as functional groups F, as an example, the diazonium salt derived from 3,5-dihydroxyaniline which has a reactive site that reacts easily with an aldehyde, in the para-position (carbon atom 4) to the diazonium group. It has been found that increased reactivity can already be obtained with a low mass ratio m(B) / m(K) of the mass m(B) of aromatic diazonium compounds B to the mass m(K) of the materials K in the surface area to be modified if a lignin L is chosen as material K, in the range of from 1 g/kg to 100 g/kg (between 0.1 % and 10 %), in the case of using the diazonium salt derived from 3,5-dihydroxyaniline as modifier B.

The diazonium group-containing modifiers B can be prepared by reaction of aromatic primary amines with nitrous acid in the presence of additional acid at low temperatures, i.e., under cooling with ice. The aromatic primary amine which may also have further functional groups is dissolved in water, in the presence of a stoichiometric excess of acid such as hydrochloric acid, the solution is cooled to a temperature of preferably between 0 °C and 5 °C, where the amine hydrochloride usually precipitates in the form of crystals. An aqueous solution of sodium nitrite is slowly added, keeping the temperature in the mentioned range, until the nitrite is no longer consumed. During the reaction, the amine hydrochloride dissolves and forms the easily soluble diazonium salt. This diazonium salt solution can react with phenolic compounds under formation of usually coloured azo compounds where both aromatic nuclei are connected via an azo group - N = N -, preferably in the para-position to a hydroxy group of the said phenolic compounds.

Among the materials K, phenolic resins such as novolaks N and resoles R are preferred which can be prepared by reaction of phenolic bodies C with aldehydes A, preferably aliphatic monoaldehydes A1A such as formaldehyde, acetaldehyde, propionaldehyde, butyric and isobutyric aldehyde; preferably formaldehyde; aliphatic dialdehydes A2A such as glyoxal, malonaldehyde (propanedial), succinaldehyde (butanedial), glutaraldehyde (pentanedial), and adipaldehyde (hexanedial), preferably glyoxal; cycloaliphatic monoaldehydes A1C, including furfural (IUPAC name: furan-2-carbaldehyde), 5-hydroxymethyl furfural (IUPAC name: 5-(hydroxymethyl)furan-2-carbaldehyde); and cycloaliphatic dialdehydes A2C, such as furane-2,5-dicarbaldehyde, and the isomeric 1,2-, 1,3-, and 1,4-cyclohexane dicarbaldehydes. Phenolic bodies C include aromatic compounds having at least one hydroxyl group bound to a carbon atom which is part of a mononuclear aromatic compound, and at least one unsubstituted carbon atom which carries a hydrogen atom, and is part of the same ring, which unsubstituted carbon atom is preferably in ortho position or para position, and less preferred, in meta position, with respect to the carbon atom carrying the hydroxyl group in the case of a six-membered ring, and has increased electron density in comparison with a carbon atom in benzene, via the mesomeric effect and/or the inductive effect. These phenolic bodies C may have linear or branched alkyl groups having up to twenty carbon atoms attached to the aromatic nuclei, where it is also possible that these alkyl substituents have the same, or different numbers of carbon atoms, or may be differently branched, or have olefinic unsaturation in their chains. This definition also includes the naturally occurring phenols in the plant anacardium occidental, the main products of which are cardanol, viz., 3-[(8Z,11Z)- pentadeca-8,11,14-trienyl]phenol, cardol, viz., 5-[(9E,12E)-pentadeca-9,12-dienyl]benzene-l,3- diol, and 2-methylcardol, viz., 2-methyl-5-[(9E,12E)-pentadeca-9,12-dienyl]benzene-l,3-diol, all commercially recovered from cashew nutshell liquid. The phenolic bodies useful for this invention are grouped into mononuclear monohydroxy aromatic compounds Cll, such as phenol itself, ortho-, meta-, and para-cresol, 2,4- and 2,6-xylenol, mononuclear aromatic compounds C12 having at least two hydroxyl groups, such as catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, and hydroxyquinol, multinuclear monohydroxy aromatic compounds CM1 having at least two aromatic rings annealed or otherwise chemically bound, such as 4-hydroxydiphenyl, alpha-naphthol, and beta-naphthol, and multinuclear aromatic compounds CM2 having at least two aromatic rings annealed or otherwise chemically bound, and at least two hydroxyl groups such as bisphenol A, IUPAC name: [2-(4-hydroxyphenyl)propan-2-yl]phenol), the mixture of isomers known as "bisphenol F", IUPAC name of a typical isomer: 4-[4-hydroxyphenyl)methyl]phenol), 4,4'- dihydroxybenzophenone, the bisphenol S mixture of isomers (4,4'-dihydroxydiphenyl- sulphone, IUPAC name: 4-[4-hydroxybenzenesulphonyl]phenol, and 4,2’-dihydroxydiphenyl- sulphone), and l,3,5-tris(4-hydroxyphenyl)benzene, IUPAC name 4-[3,5-bis(4-hydroxy- phenyl)phenyl]phenol. Further phenolic bodies which can be used in the present invention are obtained by depolymerisation or combined depolymerisation/demethylation of lignin to mono- or oligonuclear molecules.

Preferred are resoles R and novolaks N derived from phenol and formaldehyde, mixtures thereof with condensates made from lignin and formaldehyde, tannin and formaldehyde, and cocondensates from phenol and lignin, or from phenol and tannin, with formaldehyde. It is also possible, within the scope of the invention, to replace, partially or completely, formaldehyde by other aliphatic monoaldehydes and dialdehydes as detailed supra, and preferably, by aldehydes made from a natural base material, such as furfural, 5- hydroxymethylfurfural, and 2,5-furandicarbaldehyde.

Phenolic bodies also include lignins L which are generally classified into the groups of softwood, hardwood, and grass lignins. These native lignins are typically separated from the wood or other lignocelluloses in the form of "milled wood lignin" (MWL), "dioxane lignin", or "enzymatically liberated lignin". Industrially based technical lignins are by-products of chemical pulping processes which are directed to isolate the fibrous material (cellulose) from the lignocellulose: Kraft lignin (or sulphate lignin), alkali lignin (or soda lignin), and lignosulphonates are derived from lignocellulose subjected to the Kraft, the soda-anthra- quinone, and the sulphite pulping processes, respectively. A further lignin source is the so-called acid hydrolysis lignin which is still mostly converted to pellets for firing. Other lignin grades have been made accessible by more recent processes, viz., the organosolv process which provides a sulphur-free high purity lignin grade, and the hydrolysis process which is acid-catalysed and leads to formation of the so-called Hibbert ketones and of free phenolic moieties. Other emerging processes are the steam-explosion process and the ammonia-fibre expansion process. Any of these lignin materials may be used in the present invention.

Lignin materials provided by different sources and separated from the cellulose and hemicellulose accompanying materials in lignocellulose by the different processes as detailed supra differ from each other, not only in the composition with regard to the shares of 4-hydroxyphenyl-, guaiacyl- (3-methoxy-4-hydroxyphenyl-), and syringyl- (3,5-dimethyoxy- 4-hydroxyphenyl-) units of the C₉-building blocks in lignin, which is different for gymnosperms (predominantly guaiacyl units), angiosperms (both guaiacyl and syringyl units), and grass (predominantly 4-hydroxylphenyl emits), but also in the decomposition products obtained, as the decomposition process follows different routes depending on the kind of pulping process. Therefore, the lignins obtained by the processes supra have also variations in the molar mass, as reported in "Molar mass determination of lignins by size-exclusion chromatography", S. Baumberger et al., Holzforschung 2007 (61), pages 459 to 468.

It is also possible to generate fractions of high molar mass lignin, and low molar mass lignin by fractionated precipitation, see WO 2013/144453 Al. These lignin fractions may be collected, e. g., in a first mixture comprising substantially lignin oligomers and polymers of a low degree of polymerisation (hereinafter each individually, and all collectively referred to as low molar mass lignins, "LML") having from 1 to 10 monomer units, and in a second mixture comprising substantially lignin polymers (hereinafter collectively referred to as high molar mass lignins, "HML") having from 11 to 70 monomer units. Any larger number of mixtures, each comprising different groups of oligomers and polymers, may also be collected from the isolated fractions provided by controlled precipitation, or other separation processes. The molar masses of lignin can be determined according to the method described in Linping Wang et al., Holzforschung 2019; 73(4): 363 to 369, by size-exclusion chromatography of acetylated samples of the lignin fractions. These mixtures can be condensed individually with aldehydes, and mixed thereafter, or they can be condensed in sequence, and the addition time of phenol and aldehyde can be varied. In WO 2013/144453 Al, the use of certain combinations of lignin fractions of different molar mass leads to different levels of the possibility of substitution of phenol by lignin.

Lower molar mass lignins which have higher reactivity can be obtained by controlled degradation, or decomposition. Several ways of achieving controlled degradation, or decomposition have been described in the literature, including enzymatic decomposition, oxydative cleavage, pyrolysis, and treatment with radical forming systems.

It is also possible to purify lignin from any of the sources mentioned, by a plethora of methods including ultrasonic extraction, solvent extraction, dialysis, and hot water treatment. It is particularly important to remove inorganic impurities such as sulphur which stems from the The reactivity of lignin can be increased by various processes, including demethylation, methylolation/hydroxymethylation, phenolation/phenolysis, reduction, oxydation, hydrolysis, and alkalation. See, e.g. Hu, LiHong, et al., Bioresources 6(3), pages 3515 to 3525, and WO 2013/144454 Al.

All modified lignins mentioned hereinabove, as well as native lignins, and lignins obtained by the processes described in the literature can be used as lignins L, in the context of the present invention.

The natural aromatic polymers P other than lignin having aromatic moieties with increased electron density in comparison with benzene at unsubstituted carbon atoms in the said aromatic moiety are preferably selected from the group consisting of tannins T, particularly gallotannins, ellagitannins, complex tannins and condensed tannins. As these compounds have many phenolic hydroxyl groups, it has proved to be advantageous to conduct the azo coupling in a weakly alkaline medium to convert the phenolic hydroxyl groups to phenolate ions, thus providing a higher electron density in the aromatic rings and thereby facilitating the coupling reaction.

Further aromatic polymers P based on natural polymers can be used, especially based on polysaccharides such as cellulose, amylose, amylopectin, and those based on amino polysaccharides such as chitin and chitosan; in order to be able to react with the electrophilic diazonium compound B, these saccharides and aminosaccharides may be grafted with electron-rich aromatic compounds having reactive groups, e. g., (di)methoxystyrene. Such grafting can also be applied to lignins, where an improvement of reactivity of the graft product toward electrophilic substitution in the aromatic moieties has been noted.

The novolaks N, resoles R, lignin L, tannin T, and also the other polymers P can each be used alone, in combination with other components of the same class, or with at least one component of at least one other class. Therefore, combinations of at least two novolaks N1 and N2 which are chemically or physically different, combinations of at least two resoles R1 and R2 which are chemically or physically different, by changing the phenol component or the aldehyde component, or the degree of polymerisation, and also combinations of a novolak N and a resole R, and combinations of either of both or a resole R and a novolak N with one or more of a lignin L, a mixture of lignin components comprising at least two fractions LI and L2 of lignin molecules having different degrees of polymerisation or different compositions in terms of the relative abundance of H, G, and S units, and a tannin T can also be used within the scope of this invention.

The modified surface of an article, item or object M of the present invention is preferably made in the following way: a solution of a primary aromatic amine, optionally having a functional group F as detailed supra as further substituent, in an aqueous acid is prepared, and cooled to a temperature of 25 °C or less, preferably not more than 20 °C, particularly preferred, not more than 15 °C, and especially preferred, not more than 10 °C, and most preferred, not more than 5 °C, to the solution of the first step, a solution of an alkali nitrite is added preferably in an amount such that the amount of substance of nitrite ions present in the reaction

mixture is equal to the amount of substance of amino groups in the aromatic amine, and mixed at a temperature of 25 °C or less, preferably not more than 20 °C, particularly preferred, not more than 15 °C, and especially preferred, not more than 10 °C, and most preferred not more that 5 °C, (at the end of the addition of nitrite, it is recommended to add only small quantities of nitrite solution until the test for free nitrous acid using a test paper impregnated with iodide and starch remains positive for five minutes, which indicates the completion of the reaction, and then to remove the excess nitrous acid by addition of a small amount of urea or sulphaminic acid) the mixture of the second step is applied the material K having aromatic moieties with increased electron density in comparison with benzene at unsubstituted carbon atoms in the said aromatic moiety. This latter step is usually conducted in a pH range of weakly alkaline (pH > 7.5) to alkaline conditions (pH ≤ 10) as is usual in the diazo chemistry for phenolic bodies as coupling components.

It is also possible, within the scope of the present invention, to use the modifiers B in the form of solid diazonium salts, which are prepared according to any of DE 25212650 Al and EP 0 125587 Al.

In a preferred embodiment, the material K is a novolak N, or a lignin L, or a resol R, or mixture of at least two of a novolak N, a resol R, and a lignin L.

Depending on the envisaged application, the ratio m(B) / m(K) of the mass m(B) of aromatic diazonium compounds B to the mass m(K) of the surface layer in the materials K can be chosen between 0.1 % and 50 %, preferably between 0.5 % and 35 %, and particularly preferred, between 1 % and 25 %. The low mass ratios can preferably be used for colouration (colour coding) of the modified article, item or object M so obtained, using the colour developed by the diazo coupling products, while the highest mass ratios are preferably used to modify the solubility properties and the surface properties, particularly with regard to chemical and environmental stability, of the modified article, item or object M so obtained. The "mass m(B) of aromatic diazonium compounds B" refers only to the mass of the solute.

The modified articles, items or objects M made according to the present invention can be used for a wide variety of applications, particularly in composite wood materials, in abrasive materials or in friction materials such as brake pads, in heat and sound insulation materials, as foams, as binders for coatings, or as foundry moulds. They are also particularly suited for applications in elevated temperature regimes.

Further Embodiments of the Invention

The following further embodiments are encompassed:

Embodiment 2 surface modification of hydroxy-functional natural polymers N This embodiment to the modification of the surface of particulate hydroxy-functional aromatic compounds by treatment with a non-polymeric aromatic diazonium compound having no vinylsulfone structural moiety in its molecule, and to polymers based on reaction of the said modified hydroxy-functional aromatic compounds with aldehydes. It also relates to a process for the preparation of modified particulate hydroxy-functional aromatic compounds by coupling of the said hydroxy-functional aromatic compounds with nonpolymeric diazonium salts having no vinylsulfone structure in its molecule, and to a process for the preparation of polymers by reaction of the said modified hydroxy-functional aromatic compounds with aldehydes. It further relates to the use of the said polymers as binders, particularly for adhesives, coatings, composites, organic and inorganic fibre products, filled and reinforced polymer composites, for friction materials, moulding powders, and abrasives, for thermal, electrical, and acoustic insulation materials, foams, refractory materials, and foundry moulds. It has been the object of this embodiment to provide a further method to increase the reactivity of natural hydroxyfunctional polymers in particular form, comprising aromatic moieties, particularly with regard to the polycondensation reaction with aldehydes. A further object was to provide a process for the production of polymers based on the polycondensation of natural polymers comprising aromatic moieties with increased reactivity and aldehydes. A still further object was to provide a method of used of polycondensates thus produced as binders, particularly for adhesives, coatings, composites, organic and inorganic fibre products, filled and reinforced polymer composites, for friction materials, moulding powders, and abrasives, for thermal, electrical, and acoustic insulation materials, foams, refractory materials, and foundry moulds.

Modification of the surface of articles, items, and objects made from aromatic natural polymers K by azo coupling of non-polymeric aromatic diazonium salts having no vinylsulfone structure element has been described in Embodiment 1 hereinbefore, as a novel route to increase their reactivity on the surface of these articles, items, and objects. This embodiment is therefore directed to the modification of hydroxy-functional natural aromatic compounds N in solid particulate form by diazo coupling with a diazonium salt D which is a non-polymeric aromatic compound bearing a diazonium group having the structure

, where

is a monovalent anion which is preferably selected from the group

consisting of the halogenide ions

, tetrafluoroborate

, hydrogensulphate

and tosylate . The diazonium salt D may also bear further substituents in the

aromatic ring(s) of the aryl group Ar-, preferably, at least one substituent which increases the electron density of the aryl group Ar- vis-a-vis that of the corresponding unsubstituted aromatic ring system. The product of the diazo coupling is a modified hydroxy-functional natural aromatic compound NM obeying the formula N' - N = N - Ar, where the group N' - is defined by N = N' - H, the hydrogen atom H which is substituted in the diazo coupling reaction was originally bound to an aromatic moiety in the hydroxy-functional natural aromatic compound N.

In a subsequent reaction, the modified hydroxy-functional natural aromatic compound NM having the structure N' - N = N - Ar can react by addition of an aldehyde A having the structure R-C(H)=O under formation of an alkylol compound

wherein the group R is selected from the group consisting of hydrogen, an alkyl group which is linear or branched, and has from one to six carbon atoms, furan-2-yl, 5-hydroxymethyl- furan-2-yl, a further aldehyde group -C(H)=O, or an alkylenealdehyde group - R' - C(H)=O, where R' is a linear alkane-α,ω -diyl group having from one to six carbon atoms, preferably selected from the group consisting of -CH₂- (methylene, leading to malonaldehyde), -CH₂- CH₂- (ethane-l,2-diyl, leading to succinaldehyde), -CH₂-CH₂-CH₂- (propane-1, 3-diyl, leading to glutaraldehyde), and butane-l,4-diyl, leading to adipaldehyde). Preferred aldehydes are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, furfural, 5-hydroxymethyl- furfural, glyoxal, glutaraldehyde, and mixtures of these. These alkylol compounds react in a polycondensation reaction to form resins of the novolak or resol types.

The additional aryl group introduced by azo coupling with the diazonium salts D into the modified hydroxy-functional natural aromatic compound NM contributes to the increased reactivity of NM compared to that of the unmodified hydroxy-functional natural aromatic compound N in reactions thereof with aldehydes by providing additional aryl groups Ar- having free reactive sites in the aryl group where reactions with aldehydes either under alkaline conditions where an aldehyde is added in ortho or para position to, e.g., a phenolate ion to form an alkylol group in the Ar part of the modified hydroxy-functional natural aromatic compound NM, or under acidic conditions where a protonated (and optionally substituted) methyleneglycol is added in ortho- or para-position to, e.g., a phenolic hydroxyl group to form an alkylol group in the Ar part of the modified hydroxy-functional natural aromatic compound NM.

Both lignin L and tannin T as unmodified hydroxy-functional natural aromatic compounds N have only few unsubstituted carbon atoms in their aromatic rings, the wood lignins having two or three unsubstituted carbon atoms in their benzene rings in lignin from angiosperms (three in guaiacyl-units, and two in syringyl-units), three unsubstituted carbon atoms in their benzene rings in lignin from gymnosperms (in guaiacyl-units), or even four unsubstituted carbon atoms in their benzene rings in grass lignin (in p-hydroxy phenyl units). Due to the tertiary structure of lignin, steric hindrance, as discussed in "Recent Advances in Understanding the Effects of Lignin Structural Characteristics on Enzymatic Hydrolysis" by Yufeng Yuan et al., Biotechnol Biofuels (2021) 14:205, adds to the reduced chemical reactivity of lignin. A survey of such efforts to increase the reactivity of these materials, can be found in "Clicking Biobased Polyphenols: A Sustainable Platform for Aromatic Polymeric Materials", P. Buono et al., ChemSusChem, vol. 11, issue 15, pp. 2472 to 2491. Further methods are disclosed in WO 2013/145454 Al.

Tannins are a class of poly phenolic biomolecules, their molar mass ranging from about 500 g/mol for esters of sugars and gallic or digallic acid, to about 20 kg/mol for proanthocyanidines. They all comprise both phenolic and cycloaliphatic hydroxyl groups. Basic chemical structures are derived from gallic acid (3,4,5-trihydroxybenzoic acid), 1,3,5-trihydroxybenzene (phloroglucinol), and flavan-3-ol. Naturally occurring tannins are found in leaf, bud, seed, root, and stem tissues. A structural differentiation for tannins has been proposed by Khanbabee and van Ree in Natural Product Reports 5, 2001, vol. 18, pages 641 to 649, as "Gallotannins", "Ellagitannins", "Complex Tannins" and "Condensed Tannins". Gallotannins are esters of gallic acid or its depsidic derivatives with (mostly sugar-based, catechin-based or terpenoid-based) polyols. Ellagitannins comprise acidic components based on ellagic acid (2,3,7,8-tetrahydroxy-chromeno[5,4,3,c,d,e]chromene-5,10-dione) and do not contain glycosidically linked catechin units; the sugar-based polyols include, i. a., D-gluco- pyranose, D-hamamelose, sucrose, shikimic acid, and quercitols. Complex Tannins are those in which a catechin unit is bound glycosidically to a gallotannin or ellagitannin unit; and Condensed Tannins, also referred to as proanthocyanidines, are flavonoid-based oligomeric and polymeric compounds formed via linkage of the C4-atom of one catechin unit with a C8- or C6-atom of the next monomeric catechin unit. Naturally occurring tannins are usually mixtures of at least two of these four classes.

Gallotannins have two reactive unsubstituted C-H groups in a galloyl moiety, so a gallotannin which is a penta-ester of five molecules of gallic acid with one molecule of glucose has ten reactive sites; an ellagitannin which is an ester of two molecules of ellagic acid, one molecule of gallic acid, and one molecule of glucose has a total of four reactive sites in the two ellagoyl groups, and two further reactive sites in the galloyl group, leading to a total of six. In a complex tannin, the catechin units would provide a total of five reactive unsubstituted C-H groups in the two aromatic moieties of the flavanol structure, in addition to those of the moieties derived from gallo- or ellagi-tannin. Condensed tannins include trimers, tetramers, or higher oligomers of catechin, epicatechin, which (with the exception of one end catechin group) have only one reactive unsubstituted C-H group in the A rings of the catechins, and related compounds having a third phenolic hydroxyl group in the B ring of the catechins, viz., gallocatechin, and epigallocatechin, exhibit further reduced reactivity.

Cashew nutshell liquid (CNSL) is isolated from the mesocarp of cashew seeds as a dark brown and viscous oily liquid which comprises mainly anacardic acid (2-hydroxy-6- pentadecylbenzoic acid, with one, two, or three double bonds in the alkyl group; in a mass fraction of about 70 %), cardanol (3-pentadecylphenol, with one, two, or three double bonds in the alkyl group; in a mass fraction of about 5 %), and cardol (5-pentadecyl-l,3- dihydroxybenzene, with one, two, or three double bonds in the alkyl group; in a mass fraction of about 18 %). While cardanol offers sufficient unsubstituted aromatic carbon atoms to react easily with aldehydes, the long chain alkyl groups present in the molecule lead to a reduction of brittleness by replacing phenol with cardanol, in comparison with phenol-formaldehyde resins, which also leads to a reduction of flexural modulus. Additional aryl groups which are introduced by diazo coupling can therefore lead to a better balance between avoiding of brittleness, and keeping the desired stiffness.

Using diazo coupling on natural polymers comprising aromatic structures therefore offers a simple way to increase the reactivity of these polymers vis-a-vis aldehydes to a desired extent by adding unsubstituted or less substituted aromatic moieties, to adapt the mechanical properties by changing the balance between aromatic and aliphatic structures, and last but not least, options to replace at least partly aromatic intermediate products such as phenol by natural polymers.

By changing the amount and the nature of the diazonium salts which are reacted with the natural polymers, the desired changes in the properties of the reaction products can be made for any of the intended applications where phenolic resins are used.

Further special embodiments are:

2-1. A method for the preparation of modified hydroxy-functional natural aromatic compounds M from hydroxy-functional natural aromatic compounds N by diazo coupling with a diazonium salt D which is an aromatic compound bearing a diazonium group having the structure

, where

is a monovalent anion which is preferably selected from the group consisting of the halogenide ions tetrafluoroborate

hydrogensulphate

, and tosylate .

2-2. The method of embodiment 2-1 wherein the hydroxy-functional natural aromatic compounds N are selected from the group consisting of lignin L, tannin T, and cashew nutshell liquid. 2-3. The method of embodiment 2-1 or of embodiment 2-2 wherein the diazonium salt D bears at least one further substituents in the aromatic ring(s) of the aryl group Ar-.

2-4. The method of embodiment 2-3, wherein the at least one substituent changes the electron density of the aryl group Ar- vis-a-vis that of an unsubstitued benzene ring.

2-5. The method of embodiment 2-3, wherein the at least one substituent is selected from the group consisting of hydroxyl groups, alkyl groups having from one to four carbon atoms, and alkoxy groups having from one to four carbon atoms.

2-6. The product M of the method of embodiment 2-1 obeying the formula N' - N = N - Ar, where the group N' - is defined by N = N' - H, the hydrogen atom H which is substituted in the diazo coupling reaction was originally bound to an aromatic moiety in the hydroxy- functional natural aromatic compound N.

2-7. A reaction product from the modified hydroxy-functional natural aromatic compound M of embodiment 2-6 having the structure N' - N = N - Ar in an addition reaction with an aldehyde A having the structure R-C(H)=O under formation of an alkylol compound

wherein the group R is selected from the group consisting of hydrogen, an alkyl group which is linear or branched, and has from one to six carbon atoms, furan-2-yl, 5-hydroxymethyl- furan-2-yl, a further aldehyde group -C(H)=O, or an alkylenealdehyde group - R' - C(H)=O, where R' is a linear alkane-α,ω -diyl group having from one to six carbon atoms, preferably selected from the group consisting of -CH₂- (methylene, leading to malonaldehyde), -CH₂- CH₂- (ethane-l,2-diyl, leading to succinaldehyde), -CH₂-CH₂-CH₂- (propane-1, 3-diyl, leading to glutaraldehyde), and -CH₂-CH₂-CH₂-CH₂- (butane-l,4-diyl, leading to adipaldehyde).

2-8. A method of use of the reaction product of embodiment 2-7 for the preparation of condensation polymers.

Embodiment 3 Treating the surfaces of cut wood

This embodiment relates to a method for treating wood, or wood-based materials, which method improves the adhesion of coatings and glues to the surface of wood, or of wood-based materials. This method includes impregnation of wood, or of wood-based materials with a solution of a diazonium salt, and a subsequent drying step.

Before applying a varnish or a paint on wood parts, it has become customary to use a preparatory coating referred to as primer, which serves multiple purposes: the durability of the paint coating is improved, the wood part is protected against ambient and environmental damages, unwanted stains present inside the wood part are blocked, and impregnation of the wood part with the applied paint is reduced. Commonly used primers for wood are oil-based or (acrylic) latex-based. Depending on the microporosity of the wood part and the viscosity of the primer, primers can partly penetrate into the wood part, and also partly remain on its surface. After drying or crosslinking, the solid portions of the primer which are originally present in dissolved or dispersed form, or generated in the drying or crosslinking process, or both, form a film on the surface of wooden parts, and fill at least a part of open pores inside the wood part. The adhesion of coating layers or glues to a wood surface can also be improved by treating the wood surface with a primer.

In the patent EP 1 877232 Bl, a method for the treatment of the surfaces of wood or wood- based materials is disclosed which, according to claim 1, comprises the steps of

(a) impregnation of wood, wood-based materials, or wood materials for the production of wood-based materials with a curable aqueous composition which comprises at least one crosslinkable compound selected from low molar mass compounds V having at least two N- bonded groups of the formula CH₂-OR, where R is hydrogen or C₁- to C₄-alkyl, and/or a 1,2- bis-hydroxyethane-l,2-diyl group bridging two nitrogen atoms, or mixtures of compound V with at least one alcohol which is selected from C₁- to C₆-alkanols, C₂- to C₆-polyols, and oliogoalkylene glycols, the conditions of the impregnation being chosen so that the mass of curable constituents of the aqueous composition which is absorbed is at least 5 % of the dry mass of the untreated wood or woodbase material; and

(b) treatment of the material obtained in step (a) at elevated temperature and optionally further processing to give a woodbase material; and

(c) treatment of at least one surface of the wood or woodbase material to be treated with a surface treatment composition and optionally drying of the surface treatment composition in a manner known per se. The surface treatment composition mentioned hereinbefore comprises, according to claim 2, a polymeric binder and/or a prepolymer curing in the form of a polymeric binder. Per paragraph [0016] of the said patent, the crosslinkable compound is preferably selected from l,3-bis(hydroxymethyl)-4,5-dihydroxyimidazolidin-2-one and a l,3-bis(hydroxymethyl)-4, 5-dihydroxyimidazolidin-2-one modified with a C₁- to C₆-alkanol, a C₂- to C₆-polyol, and/or a polyalkylene glycol. Suitable polyols are ethylene glycol, diethylene glycol, 1,2- and 1,3-propylene glycol, 1,2-, 1,3- and 1,4-butylene glycol and glycerol. Suitable oligo- and polyalkylene glycols are in particular oligo- and poly-C₂- to C₄- alkylene glycols, especially homo- and co-oligomers of ethylene oxide and/or of propylene oxide, which, if appropriate, are obtainable in the presence of low molar mass initiators, e.g., aliphatic or cycloaliphatic polyols having at least two hydroxyl groups, such as 1,3-propane- diol, 1,3- and 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerol, trimethylolethane, trimethylolpropane, erythritol and pentaerythritol, and pentitols and hexitols, such as ribitol, arabitol, xylitol, dulcitol, mannitol and sorbitol, and inositol or aliphatic or cycloaliphatic polyamines having at least two primary amino groups, such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, propylene-l,3-diamine, dipropylenetriamine, 3-amino-l-ethyleneaminopropane, hexamethylenediamine, dihexamethylenetriamine, 1,6-bis- (3-aminopropylamino)hexane, N-methyldipropylenetriamine or polyethylenimine, among which diethylene glycol, triethylene glycol, di-, tri- and tetrapropylene glycol, and low molar mass Pluronic ® polyol brands from BASF (e.g., Plutonic® PE 3100, PE 4300, PE 4400, RPE 1720, RPE 1740; oligomeric propylene glycols; some are modified with ethylene oxide) are preferred. During the thermal treatment, the curing reaction of the curable aqueous composition which comprises at least one crosslinkable compound sets in, and "it is assumed that, owing to these properties, the compounds can penetrate into the cell walls of the wood and, on curing, improve the mechanical stability of the cell walls and reduce their swelling caused by water." See paragraph [0013], last sentence.

It has been the object of this embodiment to provide a further method to increase the adhesion between a wood surface and the coating layer or adhesive layer applied to the wood surface. In the experiments underlying this embodiment, it has been found that impregnation of wood, or of wood-based materials with a solution of a diazonium salt, and a subsequent drying step can drastically increase the adhesion of coating layers or adhesive layers applied to the wood surface to the wood part, particularly, if adhesive binders or coating binders are based on phenolic resins. It has further been found that the reactivity of natural polymers comprising aromatic moieties can be improved, particularly with regard to the polycondensation reaction thereof with aldehydes. Particularly, when adhesive layers or coating layers based on resins made from aldehydes and phenolic and/or aminoplast former compounds are applied to wood surfaces impregnated with a solution of a diazonium salt, and subjected to a subsequent drying step, the adhesion of these coating or adhesive layers to the wood part is increased. Without wishing to be bound by theory, it is apparent that formation of chemical bonds between molecules that form the structure of wood and wood materials and the diazonium salts or its (decomposition) reaction products, and the possibility of chemical bond formation with the aromatic constituents of the diazonium salts during application and curing of phenolic resin-type adhesives contribute to enhanced adhesion.

A further object was to provide an adapted process for the treatment of wood and wood materials with solutions of a diazonium salt, followed by a drying step of the impregnates which leads to an optimum performance.

This embodiment is directed to the modification of wood or wood materials by impregnation thereof with a solution of a non-polymeric diazonium salt D having no vinylsulfone group in its molecule, which is an aromatic compound bearing a diazonium group having the structure

where

is a monovalent anion which is preferably selected from the group consisting of the halogenide ions

, tetrafluoroborate

hexafluorophosphate

hydrogensulphate and tosylate . It is also possible to use a diazonium

salt comprising two molecules of a diazonium cation together with a bivalent anion such as hexafluorosilicate

. The diazonium salt D may also bear further substituents in the aromatic ring(s) of the aryl group Ar-, preferably, at least one hydroxyl group, or at least one alkoxy group, or a mixture of both hydroxyl groups and alkoxy groups.

In this description, the expression "wood materials" and "wood-based materials" shall relate not only to solid wood, but also to finely divided wood materials which include veneers, coarse shavings, chips, shreds, shavings, wood wool, strands, fine shavings, fibre bundles, fibres, flour, dust, and the like, basically according to the classification of G. G. Marra in Forest Products Journal, 22 (1972), pages 43 to 51. These materials are usually bonded using ad- hesives at elevated temperature and pressure to engineered wood products or composites, commercially most important of which are laminated veneer lumber (LVL), particle boards, medium density fibre boards, oriented strand boards (OSB), and plywood. In principle, all wood types are suitable for the invention, in particular those which can absorb a mass of water corresponding to at least 30 %, in particular at least 50 %, of their dry mass, and particularly preferably those which are classified under impregnability classes 1 and 2 in accordance with DIN-EN 350-2. These include, for example, timbers of conifers, such as pine of several species, spruce, Douglas fir, larch, Italian stone pine, fir, coastal fir, cedar and Swiss stone pine, and timbers of broad-leaved trees, e.g. maple, hard maple, acacia, birch, pear, beech, oak, alder, aspen, ash, serviceberry (amelanchier), hazel, hornbeam, cherry, chestnut, lime, American walnut, poplar, olive, elm, walnut, robinia, rubber tree, willow, Turkey oak and the like.

The diazonium salts D have preferably the structure

where

is a monovalent or divalent anion which is preferably selected from the group consisting of the halogenide ions , tetrafluoroborate

hexafluorophosphate hydrogensulphate

and tosylate . . Preferably, is tetrafluoroborate

. As has been described in

the literature, diazonium tetrafluoroborates are relatively stable in solid state. In solution they slowly decompose under elimination of nitrogen. It is likewise possible to use a diazonium salt comprising two molecules of a diazonium cation together with a bivalent anion such as hexafluorosilicate

They are usually used to form azo compounds but also form reactive aromatic cations and radicals. Especially radicals might react with many chemical species that are exposed on wood surfaces. Therefore, not only azo coupling to aromatic moieties may occur, but also, a radical coupling to carbohydrates such as cellulose or hemicellulose which are present in the wood materials.

The Ar- group in the diazonium salt D is preferably selected from the group consisting of phenyl C₆H₅-, 3-alkylphenyl, 3,5-dialkylphenyl, 3-alkoxyphenyl, 3,5-dialkoxyphenyl, 3- hydroxyphenyl, 3,5-dihydroxyphenyl, where the alkyl groups have from one to eight carbon atoms, and are preferably methyl, ethyl, n-propyl, 1 -methylethyl (= isopropyl), n-butyl, 1- methylpropyl, 2-methylpropyl, tert-butyl, and 2-ethylhexyl groups, and where the alkoxy groups have from one to eight carbon atoms, and are preferably methoxy, ethoxy, n-propoxy, 1-methylethoxy (= isopropoxy), n-butoxy, 1-methylpropoxy, 2-methylpropoxy, tert.-butoxy, and 2-ethylhexoxy groups. Particularly preferred are 3-methylphenyl, 3,5-dimethylphenyl, 3- hydroxyphenyl, and 3,5-dihydroxyphenyl. Other Ar- groups such as 4-phenoxyphenyl, stilbene-4-yl, 3,5-dihydroxystilbene-4'-yl, and 4-phenylbenzene-l-yl can also be used.

While diazonium salts D having phenolic hydroxy groups, or alkoxy groups in the Ar- group have been found to improve the bonding between the wood parts and the adhesive if adhesives based on phenolic resins are used, only small improvement has been realised when using other adhesives, particularly, isocyanate-based adhesives such as MDI (diphenyl- methylene diisocyanate) and oligomeric or polymeric MDI. In these cases, diazonium salts D based on 3-aminobenzylalcohol (IUPAC name: benzenemethanol, -3-amino) or 3-(α- hydroxyethyl)-aniline are preferred as these have aliphatic hydroxyl groups which react easily with diisocyanates.

Solutions of the diazonium salt D in water have preferably a concentration of from 0.01 mol/L to 0.5 mol/L, particularly preferred, from 0.02 mol/L to 0.25 mol/L. The solid wood part is usually sprayed with aqueous solutions of the diazonium salt D, while it is preferred for veneers or particulate wood materials to be used for the preparation of wood composite parts (engineered wood parts) to submerge or soak the these in the aqueous solutions of the diazonium salt D. Solid wood parts are free from adhering drops of solution with cloth or paper, and dried in an air stream at room temperature (22 °C) for about 24 hours. Particulate wood materials are washed with deionised water or acetone, and dried in an air stream at room temperature (22 °C) for about 24 hours. A slight discolouration of the wood material indicates successful azo coupling.

The efficiency of the treatment of wood surfaces with solutions of diazonium salts has been tested using an Automated Bonding Evaluation System (ABES) as provided by Adhesives Evaluation Systems Inc., Corvallis, Oregon, USA. Veneers to be tested are cut, a pair of veneers of the same wood type was coated with adhesive binder in the overlapping binding area. The pair of veneers is inserted into the pair of clutches at the opposite free end of the veneers, and the binder is cured in the press (which is in the central part of the measuring system) in the joint region. After curing and subsequent cooling of the joint to room temperature (21 °C) of each veneer pair, the tensile testing to obtain the shear strength was started, by gripping the free ends of the veneer pair, and applying an increasing tensile force on the clutches fixing the veneer pair at its free ends. The maximum tensile force (at break) was recorded. The recorded pulling forces were averaged over the set with identical basic data (type of wood, amount of adhesive applied, joint area) and compared for the examples according to the invention, and the control examples with non-modified wood.

In this test, the veneer modification targets an improved bonding between veneer and binder. It was found in all tests performed, either one of the veneers breaks, or the joint breaks, but never the bond between veneer and binder.

It has therefore been shown that by modifying the surfaces of the veneers, the adhesion between the wood part and the cured adhesive was strongly increased. Special embodiments are:

3-1. A method for treating wood, or wood-based materials, which method improves the adhesion of coatings and glues to the surface of wood, or of wood-based materials, wherein the method includes impregnation of wood, or of wood-based materials with a solution of a diazonium salt D, and a subsequent drying step.

3-2. The method of embodiment 3-1, wherein the wood or the wood-based materials comprise solid wood, and also finely divided wood materials which include coarse shavings, chips, shreds, shavings, wood wool, strands, fine shavings, fibre bundles, fibres, flour, and dust.

3-3. The method of embodiment 3-1 or of embodiment 3-2, wherein the wood or the wood- based materials can absorb a mass of water corresponding to at least 30 %, in particular at least 50 %, of their dry mass.

3-4. The method of embodiment 3-1 or of embodiment 3-2, wherein the wood or the wood- based materials include those from conifers, viz., pine of several species, spruce, Douglas fir, larch, Italian stone pine, fir, coastal fir, cedar and Swiss stone pine, and those from broad-leaved trees, viz., maple, hard maple, acacia, birch, pear, beech, oak, alder, aspen, ash, serviceberry (amelanchier), hazel, hornbeam, cherry, chestnut, lime, American walnut, poplar, olive, elm, walnut, robinia, rubber tree, willow, and Turkey oak.

3-5. The method of embodiment 3-1 wherein the diazonium salts D have the structure

where

is a monovalent or a divalent anion.

3-6. The method of embodiment 3-5 wherein the anion of the diazonium salts D is selected from the group consisting of the halogenide ions

tetrafluoroborate

hexafluorophosphate

hydrogensulphate tosylate and

hexafluorosilicate

! 3-7. The method of embodiment 3-5 wherein the Ar- group in the diazonium salt D is selected from the group consisting of phenyl C₆H₅-, 3-alkylphenyl, 3,5-dialkylphenyl, 3- alkoxyphenyl, 3,5-dialkoxyphenyl, 3-hydroxyphenyl, 3,5-dihydroxyphenyl, where the alkyl groups have from one to eight carbon atoms, and are preferably methyl, ethyl, n-propyl, 1- methylethyl (= isopropyl), n-butyl, 1 -methylpropyl, 2-methylpropyl, tert-butyl, and 2- ethylhexyl groups; and where the alkoxy groups have from one to eight carbon atoms, and are preferably methoxy, ethoxy, n-propoxy, 1 -methylethoxy (= isopropoxy), n-butoxy, 1- methylpropoxy, 2-methylpropoxy, tert.-butoxy, and 2-ethylhexoxy groups; 4-phenoxyphenyl, stilbene-4-yl; 3,5-dihydroxystilbene-4'-yl; and 4-phenylbenzene-l-yl.

3-8. The method of embodiment 3-5 wherein the Ar- group in the diazonium salt D is selected from 3-methylphenyl, 3,5-dimethylphenyl, 3-hydroxyphenyl, and 3,5-dihydroxy- phenyl.

3-9. The method of embodiment 3-1 wherein wood is impregnated with a solution of a diazonium salt D, rinsed with water or a solvent, or a mixture of water or a solvent, and subjected to a subsequent drying step.

3-10. The method of embodiment 3-9 wherein drying is conducted in an air or nitrogen steam, and at a temperature of between 0 °C up to 25 °C.

3-11. A method of bonding wood parts wherein at least one surface of at least one of the wood parts is treated with a solution of a diazonium salt D according to at least one of the embodiments 3-1 to 3-10, rinsing the wood part with water or a solvent, or a mixture of water or a solvent, drying the coated surface, applying a an adhesive to the treated surface of the wood part, and curing the applied coating.

3-12. The method of embodiment 3-11, wherein the adhesive is a phenolic resin.

3-13. A method of coating wood parts, comprising treating at least one surface of at least one of the wood parts with a solution of a diazonium salt D according to at least one of the claims 1 to 10, rinsing the wood part with water or a solvent, or a mixture of water or a solvent, drying the coated surface, and then, applying a decorative or protective coating to the treated surface of the wood part, and curing the applied coating.

Figures

The results from the examples hereinafter are summarised in the attached figures.

Fig-1 shows the high performance liquid chromatograms (HPLC) of the modified novolak N2 obtained in Example 2 (solid line) and of the unmodified Novolak N0 (dotted line),

Fig. 2 shows the UV-Vis spectra of the modified novolak N2 obtained in Example 2 (solid line) with the characteristic azobenzene absorption bands ππ* and nπ* transition, and of the unmodified Novolak N0 (dashed line),

Fig. 3 shows the high performance liquid chromatograms of the modified novolak N5 obtained in Example 5 (solid line) and of the unmodified Novolak N0 (dotted line),

Fig. 4 shows the UV-Vis spectra of the modified novolak N5 obtained in Example 5 (solid line) and of the unmodified Novolak N0 (dashed line),

Fig. 5 shows the high performance liquid chromatograms of the modified novolak N8 obtained in Example 8 (solid line) and of the unmodified Novolak N0 (dotted line),

Fig. 6 shows the UV-Vis spectra of the modified novolak N8 obtained in Example 8 (solid line) with the characteristic azobenzene absorption bands ππ* and nπ* transition, compared to the unmodified Novolak N0 (dashed line),

Fig. 7 shows the UV-Vis spectra of seven different reaction products of the Novolak Nil separated in the HPLC, corresponding to individual peaks in the chromatogram differing in their retention times; the different heights of the additional characteristic azobenzene absorption bands (ππ* and nπ* transition) in the UV-Vis spectra for the individual peaks in the chromatogram show that the different peaks correspond to species with different degrees of modification which have been separated in the chromatographic process, these species having different mass ratios of the mass m_B of modifier B to the mass m_N0 of the novolak substrate N0 in the separated species of N11; the different mass ratio being the cause for the difference in absorbance, Fig. 8 shows the high performance liquid chromatograms of the modified novolak N12 obtained in Example 12 (solid line) and of the unmodified Novolak N0 (dotted line),

Fig. 9 shows the UV-Vis spectra of two different reaction products of modified lignin separated in the HPLC, corresponding to individual retention times (72.5 min and 101.9 min in the chromatogram of the modified lignin) differing in their heights of the additional characteristic azobenzene absorption bands (ππ* and nπ* transition) in the UV-vis, the different mass ratio being the cause for the difference in absorbance, compared to the UV-vis absorption spectrum of unmodified lignin taken at a retention time of 70.3 min, and

Fig. 10 shows the UV-vis spectra of 3,4,5-trimethoxytoluene modified with the diazonium salt obtained in Example 1 (solid line) and that of the unmodified 3,4,5-trimethoxytoluene, as a model compound for sinapyl alcohol which is the precursor for syringyl groups in lignin; it is shown by the strong signal due to the characteristic azobenzene absorption bands (ππ* and nπ* transition) that even this highly substituted aromatic ring can be successfully modified in an azo coupling reaction.

In all HPLC chromatograms, the abscissa is the retention time, measured in the unit "min" (minutes), and the signal shown in the ordinate is the light absorption as recorded by the UV- vis detector, in arbitrary units.

In all UV-vis spectra, the measured light absorption (arbitrary units, denoted as "mAU" in the ordinate) is recorded as a function of the wavelength of the incident light of the spectrophotometer, indicated in the unit "nm" (nanometre).

Examples for Embodiment 1

Example 1 Preparation of a Diazonium Compound from Aniline

0.175 g of aniline (1.88 mmol) were dissolved in aqueous hydrochloric acid (5 mL; w(HCl) = m(HCI)/m(solution) = 18.5 %; p = 1.0904 g/mL), and the resulting mixture was cooled in an ice bath to a temperature ϑ< 5 °C. An aqueous solution of 0.13 g of sodium nitrite (molar mass M = 68.995 g/mol; 1.88 mmol) in water having a concentration of 2 mol/L (137.99 g/L) was added slowly, keeping the temperature below 5 °C. Upon completion of the addition, the solution was stirred for fifteen further minutes and was directly used in the next Example.

Example 2 Reaction of the Diazonium Compound of Example 1 with a Novolak

A novolak was prepared by charging 940 g of phenol, 9.4 g of oxalic acid, and 500 g of an aqueous solution of formaldehyde with a mass fraction of formaldehyde of 30 % to a resin kettle, and heating under reflux for three hours. Volatile substances were removed by heating, starting at normal pressure, and finally, under vacuum generated with a water jet pump, at temperatures up to 220 °C in the still. The free phenol content of this novolak corresponded to a mass fraction w(Ph) = m(Ph) / m(Novolak) = 0.05 %. This novolak is referred to as "N0" in the following examples.

1 g of this novolak N0 was dissolved at ambient temperature (20 °C) in 21 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w(NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³). The novolak solution was then cooled in an ice bath to 5 °C, and the diazonium salt solution of Example 1 was added dropwise, under formation of a reddish precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The reddish suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w(HCl) = m(HCl) / m(Solution) = 4 g / 50 g = 8 % = 80 g/kg), the precipitate was separated by filtration, and rinsed with water. The resulting solids were dried and tested via high pressure liquid chromatography (HPLC).

Example 3 HPLC analysis

A sample of 50 mg of the modified novolak N2 obtained in Example 2 was suspended in a mixture of water and tetrahydrofuran (in a mass ratio of 3:7), the suspension was homogenised during ten minutes in an ultrasonic bath at ambient temperature (20 °C). The resulting homogenised suspension was transferred via a syringe filter to a chromatography vial, and the clear filtrate was analysed in a HPLC-UV/vis system, using a gradient mixture of solvent A and solvent B, with the following conditions: solvent A: aqueous solution of lithium formate, 0.05 mol/L, pH = 3.8 solvent B: tetrahydrofuran (THF) eluent: gradient, from 95 % A to 100 % B (at t₀ = 0 min, where the mass fraction of solvent B is 5 %, to t₁₀₀ = 107 min) flow: 0.3 mL/min column: reverse phase (C18) detector: UV/vis, 200 run to 600 run

For comparison, a sample of the unmodified novolak N0 was prepared in the same way as detailed above, and also subjected to HPLC analysis.

The HPLC chromatograms are shown in Fig. 1; as can be seen, the retention times of novolak N2 obtained in example 2 (solid line) modified by additional phenyl groups from the diazonium salt derived from aniline (prepared in Example 1) are shifted towards longer retention times with regard to the unmodified novolak N0 (dotted line). The individual peaks shown in the left part of the chromatogram correspond to oligomers having different degrees of polymerisation.

UV-Vis spectra of both novolaks N0 and N2 were recorded, the additional characteristic azobenzene absorption bands (ππ* and nπ* transition) can be seen in the spectrum of Novolak N2.

Example 4 Preparation of a Diazonium Compound from Sulf anilic Acid (4- Aminobenzene Sulphonic Acid)

0.326 g of sulfanilic acid (1.88 mmol) were dissolved in aqueous hydrochloric acid (5 mL; w (HCl) = m(HCl)/m(solution) = 18.5 %; p = 1.0904 g/mL), and the resulting mixture was cooled in an ice bath to a temperature ϑ< 5 °C. An aqueous solution of 0.13 g of sodium nitrite (molar mass M = 68.995 g/mol; 1.88 mmol) in water having a concentration of 2 mol/L (137.99 g/L) was added slowly, keeping the temperature below 5 °C. Upon completion of the addition, the solution was stirred for fifteen further minutes and was directly used in the next Example. Example 5 Reaction of the Diazonium Compound of Example 4 with a Novolak

1 g of the novolak N0 as prepared in the first part of Example 2 was dissolved at ambient temperature (20 °C) in 21 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w (NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The novolak solution was then cooled in an ice bath to 5 °C, and the diazonium salt solution of Example 4 was added dropwise, under formation of a reddish precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The reddish suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w(HCl) = m(HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. The resulting solids were dried and tested via high pressure liquid chromatography.

Example 6 HPLC analysis

A sample of 50 mg of the modified novolak N5 obtained in Example 5 was suspended in a mixture of water and tetrahydrofuran (in a mass ratio of 3:7), the suspension was homogenised during ten minutes in an ultrasonic bath at ambient temperature (20 °C). The resulting homogenised suspension was transferred via a syringe filter to a chromatography vial, and the clear filtrate was analysed in a HPLC-UV/vis system, with the following conditions: solvent A: aqueous solution of lithium formate, 0.05 mol/L, pH = 3.8 solvent B: tetrahydrofuran (THF) eluent: gradient, from 95 % A to 100 % B (at t₀ = 0 min, where the mass fraction of solvent B is 5 %, to t₁₀₀ = 107 min) flow: 0.3 mL/min column: reverse phase (C18) detector: UV/vis, 200 nm to 600 nm

For comparison, a sample of the unmodified novolak N0 was prepared in the same way as detailed above, and also subjected to HPLC analysis. The chromatograms are shown in Fig. 3; as can be seen, the retention times of novolak N5 obtained in example 5 modified by additional phenyl-4-sulphonic acid groups from the diazonium salt derived from sulfanilic acid (prepared in Example 4) are shifted towards shorter retention times with regard to the unmodified novolak N0, meaning that the modified novolak N5 is more hydrophilic than the unmodified novolak N0. The individual peaks shown in the left part of the chromatogram correspond to oligomers having different degrees of polymerisation.

UV-Vis spectra of both novolaks N0 and N5 were recorded (Fig. 4), the additional characteristic azobenzene absorption bands (ππ* and nπ* transition) can be seen in the spectrum of Novolak N5.

Example 7 Preparation of a Diazonium Compound from Cleve's Acid- 1,6 (1-Amino- naphthalene-6-sulphonic Acid, 5-Amino-2-naphfhalenesulphonic Acid)

0.420 g of l-aminonaphthalene-6-sulphonic acid (1.88 mmol) were dissolved in aqueous hydrochloric acid (5 mL; w(HCl) = m(HCl)/m(solution) = 18.5 %; p = 1.0904 g/mL), and the resulting mixture was cooled in an ice bath to a temperature ϑ< 5 °C. An aqueous solution of 0.13 g of sodium nitrite (molar mass M = 68.995 g/mol; 1.88 mmol) in water having a concentration of 2 mol/L (137.99 g/L) was added slowly, keeping the temperature below 5 °C. Upon completion of the addition, the solution was stirred for fifteen further minutes and was directly used in the next Example.

Example 8 Reaction of the Diazonium Compound of Example 7 with a Novolak

1 g of the novolak N0 as prepared in the first part of Example 2 was dissolved at ambient temperature (20 °C) in 21 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w (NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The novolak solution was then cooled in an ice bath to 5 °C, and the diazonium salt solution of Example 7 was added dropwise, under formation of a reddish precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The reddish suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w (HCl) = m(HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. The resulting solids were dried and tested via high pressure liquid chromatography.

Example 9 HPLC analysis

A sample of 50 mg of the modified novolak N8 obtained in Example 8 was suspended in a mixture of water and tetrahydrofuran (in a mass ratio of 3:7), the suspension was homogenised during ten minutes in an ultrasonic bath at ambient temperature (20 °C). The resulting homogenised suspension was transferred via a syringe filter to a chromatography vial, and the clear filtrate was analysed in a HPLC-UV/vis system, with the following conditions: solvent A: aqueous solution of lithium formate, 0.05 mol/L, pH = 3.8 solvent B: tetrahydrofuran (THF) eluent: gradient, from 95 % A to 100 % B (at t₀ = 0 min, where the mass fraction of solvent B is 5 %, to t₁₀₀ = 107 min) flow: 0.3 mL/min column: reverse phase (CIS) detector: UV/vis, 200 nm to 600 nm

For comparison, a sample of the unmodified novolak N0 was prepared in the same way as detailed above, and also subjected to HPLC analysis. The chromatograms are shown in Fig. 5; as can be seen, the retention times of novolak N8 obtained in example 8 modified by additional naphthalyl-sulphonic acid groups from the diazonium salt derived from Cleve's acid 1,6 (prepared in Example 7) show only a little shifted of the retention times with regard to the unmodified novolak N0, meaning that the modified novolak N8 has approximately the same hydrophilicity as the unmodified novolak N0, due to the contrary effects of the naphthalene group (shift to less hydrophilic) and of the sulphonic acid group (shift to more hydrophilic). The individual peaks shown in the left part of the chromatogram correspond to oligomers having different degrees of polymerisation. UV-Vis spectra of both novolaks N0 and N8 were recorded (Fig. 6), the additional characteristic azobenzene absorption bands (ππ* and nπ* transition) can be seen in the spectrum of Novolak N8.

Example 10 Preparation of a Diazonium Compound from 3- Aminophenol

0.205 g of 3-aminophenol (1.88 mmol) were dissolved in aqueous hydrochloric acid (5 mL; w(HCl) = m(HCl)/m(solution) = 18.5 %; p = 1.0904 g/mL), and the resulting mixture was cooled in an ice bath to a temperature ϑ< 5 °C. An aqueous solution of 0.13 g of sodium nitrite (molar mass M = 68.995 g/mol; 1.88 mmol) in water having a concentration of 2 mol/L (137.99 g/L) was added slowly, keeping the temperature below 5 °C. Upon completion of the addition, the solution was stirred for fifteen further minutes and was directly used in the next Example.

Example 11 Reaction of the Diazonium Compound of Example 10 with a Novolak

1 g of the novolak N0 as prepared in the first part of Example 2 was dissolved at ambient temperature (20 °C) in 21 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w(NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The novolak solution was then cooled in an ice bath to 5 °C, and the diazonium salt solution of Example 10 was added dropwise under formation of a reddish precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The reddish suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w(HCl) = m(HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. The resulting solids were dried and tested by HPLC as described supra. The UV-vis spectra of seven different reaction products of the Novolak Nil separated in the HPLC, corresponding to individual peaks in the chromatogram differing in their retention times, are shown in Fig. 7. The different heights of the additional characteristic azobenzene absorption bands (ππ* and nπ* transition) in the UV-Vis spectra for the individual peaks in the chromatogram show that the different peaks correspond to species with different degrees of modification which have been separated in the chromatographic process, which have different mass ratios of the mass m_B of modifier B to the mass m_N0 of the novolak substrate N0 in the separated species. The different mass ratio is the cause for the difference in absorbance.

Example 12 Reaction of the Diazonium Compound of Example 1 with Lignin

1.84 g of lignin was dissolved at ambient temperature (20 °C) in 37 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w(NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The lignin solution was then cooled in an ice bath to 5 °C, and the diazonium salt solution of Example 4 was added dropwise, under formation of a dark brown precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The dark brown suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w(HCl) = m(HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. The resulting solids were dried and tested via high pressure liquid chromatography.

Example 13 HPLC analysis

A sample of 50 mg of the modified lignin obtained in Example 12 was suspended in a mixture of water and tetrahydrofuran (in a mass ratio of 3 : 7), the suspension was homogenised during ten minutes in an ultrasonic bath at ambient temperature (20 °C). The resulting homogenised suspension was transferred via a syringe filter to a chromatography vial, and the clear filtrate was analysed in a HPLC-UV/vis system, with the following conditions: solvent A: aqueous solution of lithium formate, 0.05 mol/L, pH = 3.8 solvent B: tetrahydrofuran (THE) eluent: gradient, from 95 % A to 100 % B (at t₀ = 0 min, where the mass fraction of solvent B is 5 %, to t₁₀₀ = 107 min) flow: 0.3 mL/min column: reverse phase (C18) detector: UV/vis, 200 nm to 600 nm For comparison, a sample of the unmodified lignin was prepared in the same way as detailed above, and also subjected to HPLC analysis.

The chromatograms are shown in Fig. 8 ; as can be seen, the retention times of the modified lignin of example 12 which was modified by additional phenyl groups from the diazonium salt derived from aniline (prepared in Example 1) are shifted towards longer retention times with regard to the unmodified lignin.

Example 14 Reaction of the Diazonium Compound of Example 1 with 3,4,5-Trimethoxy- toluene

0.91 g of 3,4,5-trimethoxytoluene (as a model compound for lignin) and 0.44 g of pyridine were dissolved at ambient temperature (20 °C) in 15 mL of acetonitrile. The 3,4,5-tri- methoxytoluene solution was then cooled in an ice bath to 5 °C, and the diazonium salt solution of Example 1 was added dropwise, under formation of a yellow to orange colour. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The dark orange solution was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w(HCl) = m(HCl) / m(Solution) = 4 g/50 g = 8 %), the separating oil was separated by decantation. The resulting dark orange liquid was tested via high pressure liquid chromatography.

Example 15 HPLC analysis

A sample of 50 mg of the modified 3,4,5-trimethoxytoluene obtained in Example 14 was dissolved in a mixture of water and tetrahydrofuran (in a mass ratio of 3:7 at ambient temperature (20 °C). The resulting solution was transferred via a syringe filter to a chromatography vial, and the clear filtrate was analysed in a HPLC-UV/vis system, with the following conditions: solvent A: aqueous solution of lithium formate, 0.05 mol/L, pH = 3.8 solvent B: tetrahydrofuran (THF) eluent: gradient, from 95 % A to 100 % B (at t₀ = 0 min, where the mass fraction of solvent B is 5 %, to t₁₀₀ = 107 min) flow: 0.3 mL/min column: reverse phase (C18) detector: UV/vis, 200 nm to 600 run

In similar experiments, arylamines have been prepared with one or more than one additional substituents on the aromatic ring(s) selected from the group consisting of hydroxyl groups, linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, tert.-butyl, n-hexyl, n-octyl, n-nonyl, n-dodecyl, and stearyl, hydroxyl groups, linear or branched alkoxy groups -O-C_nH_2n+1 having from n = 1 to n = 20 carbon atoms, preferably methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert.- butyoxy, n-hexoxy, n-octoxy, n-nonoxy, n-dodecoxy, and stearoxy, linear or branched alkoxycarboxy groups -C(O)-O-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms, preferably methoxycarboxy, ethoxycarboxy, n-propoxycarboxy, isopropoxycarboxy, n-butoxycarboxy, tert-butyoxycarboxy, n-hexoxycarboxy, n-octoxycarboxy, n-nonoxycarboxy, n-dodecoxy- carboxy, and stearoxycarboxy, linear or branched alkylcarbonyl groups -C(O)-C_nH_2n+1 having from n = 1 to n = 20 carbon atoms, preferably methylcarbonyl, ethylcarbonyl, n- propylcarbonyl, isopropylcarbonyl, n-butylcarbonyl, tert.-butylcarbonyl, n-hexylcarbonyl, n- octylcarbonyl, n-nonylcarbonyl, n-dodecylcarbonyl, and stearylcarbonyl, aryl groups having from six to twenty carbon atoms, preferably phenyl, 1- and 2-naphthyl, 1-, 2-, or 9-anthracenyl, heteroaryl groups having from six to twenty carbon atoms and at least one hetero atom which is selected from the group consisting of oxygen -O-, sulphur -S-, nitrogen -N= or imine -N(H)-, which, in the case of two or more hetero atoms, these may be the same, or may be different from each other, preferably furan-2-yl, or -3-yl, thiophen-2-yl, or -3-yl, pyrrol-2-yl, or -3-yl, pyrazol-3-yl, -4-yl, or -5-yl, imidazole-2-yl, -4-yl, or -5-yl, l,2,3-triazole-4-yl, or -5-yl, 1,2,4- triazole-3-yl, or-5-yl, isoxazole-3-yl, -4-yl, or -5-yl, oxazole-2-yl, -4-yl, or -5-yl, isothiazole-3-yl, -4-yl, or -5-yl, thiazole-2-yl, -4-yl, or -5-yl, pyridine-2-yl, -3-yl, or -4-yl, pyridazine-3-yl, or-4-yl, pyrimidine-2-yl, -4-yl, or -5-yl, pyrazine-2-yl, l,3,5-triazine-2-yl, l,2,4-triazine-2-yl, -5-yl or -6-yl, l,2,3-triazine-4-yl or -5-yl, alkylamino groups and dialkyl amino groups

where R_N1 and R_N2 may be the same, or may be different from each other, and are indepen- dently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, tert. -butyl, n-hexyl, n- octyl, n-nonyl, n-dodecyl, and stearyl; phosphate -O-P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from H, linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, tert.-butyl, n-hexyl, n-octyl, n-nonyl, n-dodecyl, and stearyl; aldehyde groups -C(O)-H; phosphonate -P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from H, linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, tert.-butyl, n-hexyl, n-octyl, n-nonyl, n-dodecyl, and stearyl; cyanate -0-C≡ N groups, nitro -NO₂ groups, thiol -SH groups, halogen -F, -Cl, -Br, -I groups; nitrile groups -C≡N; (per)fluoroalkyl groups, preferably pentafluoroethyl, hexafluoroisopropyl, and enneafluorbutyl, and oligo- and poly-siloxane groups.

For the siloxane groups, it has shown to be preferable to introduce phenolic hydroxyl groups or (aromatic) amino groups by the azo-coupling step, and react these intermediates in a second step with reactive siloxane reagents such as epoxy-functional or anhydride-functional silicones, or to introduce epoxy groups or anhydride groups by the azo-coupling step, and react these intermediates with reactive siloxane reagents such as mercapto -functional silicones or amino-functional silicones. Depending on their chemical nature, these groups are hydrophilic or hydrophobic, and add a further functionality to the diazonium group- containing modifiers B, and thus change the physicochemical properties of the resins M so modified, e. g., hydrophilicity or hydrophobicity, cohesion and adhesion properties, solubility, light and chemical resistance, and chemical reactivity.

It has been possible to treat surfaces coated with phenolic resins PF and modified phenolic resins MPF as defined supra with these diazonium group-containing modifiers B. Such treatment has led to modified surface properties including non-wetting surfaces, or surfaces having improved chemical and solvent resistance.

Examples for Embodiment 2 Example 2-1 Preparation of a Diazonium Salt from 3-Aminophenol

2.05 g of 3-aminophenol (18.8 mmol) were dissolved in aqueous hydrochloric acid (50 mL; w(HCl) = m(HCl)/m(solution) = 18.5 %; density ϱ = 1.0904 g/mL), and the resulting mixture was cooled in an ice bath to a temperature ϑ < 5 °C. An aqueous solution of 1.3 g of sodium nitrite (molar mass M = 68.995 g/mol; 18.8 mmol) in water having a concentration of 2 mol/L (137.99 g/L) was added slowly, keeping the temperature below 5 °C. Upon completion of the addition, the solution was stirred for fifteen further minutes and was directly used in the next Example.

Example 2-2 Diazo Coupling of Lignin with 3-Hydroxyphenyldiazoniumchlorid

1.84 g of lignin was dissolved at ambient temperature (20 °C) in 37 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w(NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The lignin solution was then cooled in an ice bath to 5 °C, and 5.5 mL (1/10) of the diazonium salt solution of Example 2-1 was added dropwise, under formation of a dark brown precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The dark brown suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w (HCl) = m(HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. This product is referred to as LI.

Example 2-3

1.84 g of lignin was dissolved at ambient temperature (20 °C) in 37 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w(NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The lignin solution was then cooled in an ice bath to 5 °C, and 11 mL (2/10) of the diazonium salt solution of Example 1 was added dropwise, under formation of a dark brown precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The dark brown suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w (HCl) = m(HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. This product is referred to as L2.

Example 2-4

1.84 g of lignin was dissolved at ambient temperature (20 °C) in 37 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w (NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The lignin solution was then cooled in an ice bath to 5 °C, and 16.5 mL (3/10) of the diazonium salt solution of Example 2-1 was added dropwise, under formation of a dark brown precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The dark brown suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w(HCl) = m (HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. This product is referred to as L3.

Example 2-5

1.84 g of lignin was dissolved at ambient temperature (20 °C) in 37 mL of an aqueous sodium hydroxide solution (having a concentration of 2 mol/L, corresponding to a mass fraction w(NaOH) = m(NaOH)/ m(Solution) of 79.994 g/1086 g = 7.37 %, with the density of the solution at this temperature being 1086 kg/m³ = 1.086 g/cm³). The lignin solution was then cooled in an ice bath to 5 °C, and 22 mL (4/10) of the diazonium salt solution of Example 2-1 was added dropwise, under formation of a dark brown precipitate in the stirred solution. When the addition was completed, the reaction mixture was stirred at room temperature (20 °C) for a further hour. The dark brown suspension was admixed to 50 mL of a dilute aqueous solution of hydrochloric acid (mass fraction w (HCl) = m(HCl) / m(Solution) = 8 %), the precipitate was separated by filtration, and rinsed with water. This product is referred to as L4.

Example 2-6 Reaction Rate with Formaldehyde

Products L1 through L4 each comprise approximately 10 mmol of monolignol units. A further product L0 was also taken from the unmodified lignin that was also used as educt in examples 2 to 5. Resoles were made from products L0, LI, L2, L3, and L4, each in a 50 mL vessel under stirring and heating to 70 °C, 0.82 g of aqueous formaldehyde solution was added, together with 0.05 g of bariumhydroxide. After two hours, stirring was stopped, and dilute sulphuric acid was added to bring the pH to about 6.5. While the formaldehyde had been completely consumed in L4, only approximately 10 % of the formaldehyde added was consumed in L0.

This set of experiments shows that the diazo coupling can modify lignin so that it takes part in a condensation reaction to form a phenolic resin.

Examples for Embodiment 3

Examples

Example 3-1 Preparation of a Diazonium Salt from 3- Aminophenol

2.052 g of 3-aminophenol (molar mass: 109.128 g/mol; 18.8 mmol) were dissolved in a mixture of 45 g of deionised water and 5.07 g of an aqueous solution of tetrafluoroboric acid (mass fraction of HBF₄ in the solution: w (HBF₄) = m(HBF₄)/m( solution) = 48.2 %), and the resulting mixture was cooled in an ice bath to a temperature ϑ< 5 °C. An aqueous solution of 1.3 g of sodium nitrite (molar mass M = 68.995 g/mol; 18.8 mmol) in water having a concentration of 2 mol/L (137.99 g/L) was added slowly, keeping the temperature below 5 °C. Upon completion of the addition, the solution was stirred for fifteen further minutes and was diluted by adding further 320 mL of deionised water. The resulting solution was kept cool (below 5 °C) and was directly used in the next Examples.

Example 3-2 Impregnation of Spruce Veneers

The size of spruce veneers was approximately 120 mm x 21 mm x 3.5 nun (length, width and thickness). Veneers were submerged to cover about one quarter of the veneer length in the diluted solution of Example 3-1 for ten minutes. The impregnated veneers were then washed with deionised water or acetone, and dried in an air stream at room temperature (22 °C) for about 24 hours. A slight discolouration of the veneers indicates successful azo coupling. 27 mg each of a phenolic resin binder was applied with a spatula on one side of the impregnated zone of two identical veneers, and each two coated veneers were positioned in the measuring device so that the coated areas overlapped to obtain a binding area of approximately 21 mm x 15 mm. Curing conditions in the testing instrument were set to 110 °C and 270 s. After curing and subsequent cooling of the joint to room temperature (21 °C), the tensile testing to obtain the shear strength was started.

Ten impregnated veneer pairs and ten control veneer pairs which were non-modified were subjected to tensile testing, and the average of the force to break was determined for the two sets as 1.48 kN and 1.13 kN for the control set.

Example 3-3 Impregnation of Beech Veneers

The size of beech veneers was approximately 117 mm x 20 mm x 0.6 mm (length, width and thickness). Veneers were submerged to cover about one quarter of the veneer length in the diluted solution of Example 3-1 for ten minutes. The impregnated veneers were then washed with deionised water or acetone, or a mixture of both, and dried in an air stream at room temperature (22 °C) for about 24 hours. A slight discolouration of the veneers indicates successful azo coupling.

Three sets with different mass of phenolic resin binder were prepared by applying the binder with a spatula on one side of the impregnated zone of two identical veneers, and each two coated veneers were positioned in the measuring device so that the coated areas overlapped to form a binding area of 20 mm x 5 mm. For the first set (3a), the mass of binder in the binding area for each of the three pairs was 9 mg on each of the two coated veneers, for the second set (3b), the mass of binder for each of the three pairs was 7.5 mg each of the two coated veneers, and for the third set (3c), the mass of binder for each of the three pairs was 5 mg on each of the two coated veneers. A further control set was prepared based on veneers that had not been impregnated, and where the same mass of binder was applied as in sets 3a to 3 c. These control sets are referred to as 3a', 3b', and 3c'. Curing conditions in the testing instrument were set to 110 °C and 120 s. After curing and subsequent cooling of the joint to room temperature (21 °C) of each veneer pair, the tensile testing to obtain the shear strength was started, by gripping the free ends of the veneer pair, and continually increasing the elongation under recording of the pulling force measured until breaking of the adhesive bond. The recorded pulling forces were averaged over the set with identical basic data (type of wood, amount of adhesive applied, joint area) and compared for the examples according to the invention, and the control examples with non-modified wood.

Nine impregnated veneer pairs and nine control veneer pairs which were non-modified were subjected to tensile testing, and the average of the force to break was determined for the sets 3a, 3b and 3c, as 1.22 kN, with no statistically meaningful influence of the amount of adhesives applied on the force to break, and 0.99 kN for the control set of 3a', 3b', and 3c' (also with no statistically meaningful influence of the amount of adhesives applied on the force to break). As in Example 2, the average force to break was significantly increased when the wood material was impregnated with a diazonium salt that has a hydroxyl group as further substituent in the aromatic ring bearing the diazonium group.

Similar results have been obtained with diazonium salts diazonium salts D having the structure

, where

is a monovalent anion which is preferably selected from the group consisting of the halogenide ions

, tetrafluoroborate

hexafluoro- phosphate , hydrogensulphate and tosylate and where the Ar-

group in the diazonium salt D is selected from the group consisting of phenyl C₆H₅-, 3- alkylphenyl, 3,5-dialkylphenyl, 3-alkoxyphenyl, 3,5-dialkoxyphenyl, 3-hydroxyphenyl, 3,5- dihydroxyphenyl, where the alkyl groups have from one to eight carbon atoms, and are preferably methyl, ethyl, n-propyl, 1-methylethyl (= isopropyl), n-butyl, 1 -methylpropyl, 2- methylpropyl, tert.-butyl, and 2-ethylhexyl groups, and where the alkoxy groups have from one to eight carbon atoms, and are preferably methoxy, ethoxy, n-propoxy, 1 -methylethoxy (= isopropoxy), n-butoxy, 1 -methylpropoxy, 2-methylpropoxy, tert.-butoxy, and 2-ethylhexoxy groups, whereof 3-methylphenyl, 3,5-dimethylphenyl, 3-hydroxyphenyl, and 3,5-dihydroxy- phenyl are particularly preferred. Other Ar- groups such as 4-phenoxyphenyl, stilbene-4-yl, 3,5-dihydroxystilbene-4'-yl, and 4-phenylbenzene-l-yl can also be used. It is also possible to use a diazonium salt comprising two molecules of a diazonium cation together with a bivalent anion such as hexafluorosilicate

Claims

Claims

1. A method for the modification of surfaces of articles, items or bodies made from aromatic polymer materials K by treating the surface of any of these articles, items or bodies with non-polymeric aromatic diazonium compounds B, wherein aromatic diazonium compounds B having a diazonium group of formula

bound to an aromatic carbon atom are coupled to the said aromatic polymers K via an azo coupling reaction, which diazonium compounds B do not comprise vinylsulfone structures and either carry no additional substituent in their aromatic structure, or preferably carry at least one further functional group F which is capable of modifying the reactivity, solubility, interfacial properties such as surface tension, adsorption, optical, electrical, chemical and mechanical properties, of the surface of an article, object or body made from the aromatic polymers K to obtain an article, object or body M with such changed surface properties.

2. The modified articles, objects or bodies M obtained by the method of claim 1, wherein the resinous oligomeric or polymeric phenolic materials K are prepared by reaction of phenolic bodies C with aldehydes A, wherein the aldehydes are selected from the group consisting of aliphatic monoaldehydes A1A, cycloaliphatic monoaldehydes A1C, aliphatic dialdehydes A2A, and cycloaliphatic dialdehydes A2C, and of mixtures of two or more of these.

3. The modified articles, objects or bodies M of obtained by the method of claim 1 or of claim 2, wherein the resinous oligomeric or polymeric phenolic materials K are prepared by reaction of phenolic bodies C with aldehydes A, wherein the phenolic bodies C are selected from the group consisting of mononuclear monohydroxy aromatic compounds Cll, mononuclear aromatic compounds C12 having at least two hydroxyl groups bound to an aromatic carbon atom, multinuclear monohydroxy aromatic compounds CM1, and multinuclear aromatic compounds CM2 having at least two hydroxyl groups bound to an aromatic carbon atom.

4. The modified articles, objects or bodies M of claim 2 or of claim 3, wherein the aliphatic monoaldehydes A1A are selected from the group consisting of formaldehyde, acetaldehyde, propanal, n-butanal, 2-methyl-n-butanal, n-pentanal, and methylglyoxal (2- oxopropanal), and of mixtures of two or more of these.

5. The modified articles, objects or bodies M of claim 2 or of claim 3, wherein the aliphatic dialdehydes A2A are selected from the group consisting of glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, and adipaldehyde, and of mixtures of two or more of these.

6. The modified articles, objects or bodies M of claim 2 or of claim 3, wherein the cycloaliphatic monoaldehydes A1C are selected from the group consisting of furfural (IUPAC name: furan-2-carbaldehyde), and 5-hydroxymethylfurfural (IUPAC name: 5-(hydroxymethyl)furan-2-carbaldehyde), and of mixtures of two or more of these.

7. The modified articles, objects or bodies M of claim 2 or of claim 3, wherein the cycloaliphatic dialdehydes A2C are selected from the group consisting of furane-2,5- dicarbaldehyde, and the isomeric 1,2-, 1,3-, and 1,4-cyclohexane dicarbaldehydes, and of mixtures of two or more of these.

8. The modified articles, objects or bodies M of claim 2 or of claim 3, wherein the phenolic bodies C are selected from the group consisting of phenol itself (hydroxybenzene), ortho-cresol, meta-cresol, para-cresol, 2,4-xylenol, 2,6-xylenol, and resorcinol, and combinations of two or more thereof.

9. The modified articles, objects or bodies M of claim 2 or of claim 3, wherein the aldehyde A is selected from the group consisting of formaldehyde, glyoxal, 5- hydroxymethylfurfural, and combinations of two or more thereof.

10. The modified articles, objects or bodies M of claim 2 or of claim 3, wherein the resinous oligomeric or polymeric phenolic materials K are selected from the group consisting of novolaks N, resoles R, polymers PL based on reaction products of aldehydes A with lignin L, polymers PT based on reaction products of aldehydes A with tannin T, and modified novolaks and resoles where at least a part of the phenols in the synthesis thereof has been replaced by lignin L or tannin T or other naturally occurring substituted phenols, or a mixture of two or more thereof.

11. The modified articles, objects or bodies M of any one of claims 1, 2, 3, or 10, wherein the aromatic diazonium compounds B having a diazonium group of formula

bound to an aromatic carbon atom, are selected from the group consisting of aromatic diazonium compounds B which carry no additional group, and of aromatic diazonium compounds B which carry at least one further functional group F which is selected from the group consisting of hydroxyl groups -OH; acid functional groups selected from the group consisting of carboxylic acid groups -C(O) - OH; sulphonic acid groups -S(O₂) - OH; phosphonic acid groups -P(O)(OH)₂; linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkoxy groups -O-C_nH_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkoxycarboxy groups -C(O)-O-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkylcarbonyl groups -C(O)-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; aryl groups having from six to twenty carbon atoms; heteroaryl groups having from six to twenty carbon atoms and at least one hetero atom which is selected from the group consisting of oxygen -O-, sulphur -S-, nitrogen -N= or imine -N(H)-, where, in the case of two or more hetero atoms, these heteroatoms or heteroatom-containing groups, may be the same, or may be different from each other; aldehyde groups -C(O)-H; secondary amino groups where R_N1 and R_N2 may be the same, or may be dif-

ferent from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; phosphate -O-P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; phosphonate -P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; cyanate -O-C≡N groups; cyano (nitrile) -C≡N groups; nitro -NO₂ groups; thiol -SH groups; halogen -F, -Cl, -Br, -I groups;

(per)fluoroalkyl groups; oligo-siloxane groups; poly-siloxane groups; and any combination of two or more thereof.

12. The modified articles, objects or bodies M of claim 11, wherein the aromatic diazonium compounds B having a diazonium group of formula

bound to an aromatic carbon atom are selected from the group consisting of ortho-, meta-, and para- aminobenzene sulphonic acids, aminonaphthalene sulphonic acids including naphthionic acid (l-aminonaphthalene-4- sulphonic acid), Laurent acid (l-aminonaphthalene-5-sulphonic acid), peri acid (1- aminonaphthalene-8-sulphonic acid), Tobias acid (2-aminonaphthalene-l-sulphonic acid), Dahl acid I (2-aminonaphthalene-5-sulphonic acid), Bronner acid (2-aminonaphthalene-6- sulphonic acid), Erdmann acid (2-aminonaphthalene-7-sulphonic acid), and aminocroceine acid (2-aminonaphthalene-8-sulphonic acid), aminonaphthalene disulphonic acids including Freund acids II and III (1-aminonaphthalene- 3,6-disulphonic acid and 1-aminonaphthalene- 3,7-disulphonic acid), amino epsilon acid (l-aminonaphthalene-3,8-disulphonic acid), Dahl acids II and III (l-aminonaphthalene-4,6-disulphonic acid and l-aminonaphthalene-4,7- disulphonic acid), C acid (2-aminonaphthalene-4,8-disulphonic acid), amino G acid (2- aminonaphthalene-5,8-disulphonic acid), and further, the hydroxyaminosulphonic acid referred to as Boninger acid (l-aminonaphthalene-2-hydroxy-4-sulphonic acid), and the aminotrisulphonic acid "Koch acid" (l-aminonaphthalene-3,6,8-trisulphonic acid).

13. A method for the preparation of the modified articles, objects or bodies M of claim 1, with the steps of preparing a solution in an aqueous acid, of an aromatic amine having optionally, at least one further functional group F which is selected from the group consisting of hydroxyl groups -OH; acid functional groups selected from the group consisting of carboxylic acid groups -C(O) - OH; sulphonic acid groups -S(O₂) - OH; phosphorite acid groups -P(O)(OH)₂; linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkoxy groups -O-C_nH_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkoxycarboxy groups -C(O)-O-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; linear or branched alkylcarbonyl groups -C(O)-C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; aryl groups having from six to twenty carbon atoms; heteroaryl groups having from six to twenty carbon atoms and at least one hetero atom which is selected from the group consisting of oxygen -O-, sulphur -S-, nitrogen -N= or imine -N(H)-, where, in the case of two or more hetero atoms, these heteroatoms or heteroatom-containing groups, may be the same, or may be different from each other; aldehyde groups -C(O)-H; alkylamino groups and dialkylamino groups , where R_N1 and

R_N2 may be the same, or may be different from each other, and are indepen- dently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; phosphate -O-P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; phosphonate -P(O)(OR_P)₂ groups, where the groups R_P may be the same, or may be different from each other, and are independently selected from linear or branched alkyl groups -C_n H_2n+1 having from n = 1 to n = 20 carbon atoms; cyanate -O-C≡N groups; cyano (nitrile) -C≡N groups; nitro -NO₂ groups; thiol -SH groups; halogen -F, -Cl, -Br, -I groups;

(per)fluoroalkyl groups; oligo-siloxane groups; poly-siloxane groups, cooling the solution of the first step to a temperature of 25 °C or less, adding to the cooled solution of the second step, a solution of an alkali nitrite, and mixing the resulting combined solution at a temperature of 25 °C or less, and keeping the mixture until the nitrite is consumed and the reaction is completed, under formation of a diazonium compound B, adding the mixture of the third step comprising a diazonium compound B to a solution or slurry of at least one oligomeric or polymeric phenolic material K having aromatic moieties with increased electron density in comparison with benzene at unsubstituted carbon atoms in the said aromatic moiety, wherein the quantity of the mixture of the third step is chosen such that the ratio m(B) / m(K) of the mass m(B) of aromatic diazonium compounds B to the mass m(K) of the resinous oligomeric or polymeric phenolic materials K can be chosen between 0.1 % and 50 %, preferably between 0.5 % and 35 %, and particularly preferred, between 1 % and 25 %.

14. A method of use of the modified articles, objects or bodies M of claim 1, or made according to claim 13, as adhesives for composite wood materials, as binders for organic or inorganic fibre products, as binders for coatings, as binders in abrasive materials or in friction materials such as brake pads, in heat and sound insulation materials, as foams, or as foundry moulds.