WO1997045395A1

WO1997045395A1 - Quaternary ammonium compounds

Info

Publication number: WO1997045395A1
Application number: PCT/SE1997/000873
Authority: WO
Inventors: Marek A. Gorzynski; J. Heribert Macherey
Original assignee: Eka Chemicals Ab
Priority date: 1996-05-28
Filing date: 1997-05-27
Publication date: 1997-12-04
Also published as: JPH11511792A; AU2987297A; EP0904261A1; CA2255844A1

Abstract

The invention relates to cationic polyurethanes and aqueous dispersions of cationic polyurethanes, their preparation and use as sizing agents in the making of paper. The invention further relates to hydroxy-functional quaternary ammonium compounds and compositions thereof, their preparation and use in the production of cationic polyurethanes.

Description

Quaternary ammonium compounds

The present invention generlly relates to quaternary ammonium compounds. More specifically, the invention relates to cationic polyurethanes and aqueous dispersions of cationic polyurethanes, their preparation and use in papermaking. The invention further relates to hydroxy-functional quaternary ammonium compounds and compositions thereof, their preparation and use in the production of cationic polyurethanes.

It is known in the papermaking art to use cationic polyurethanes (CPUR) as sizing agents in order to delay or prevent the absorption and spreading of aqueous solutions in sized paper products. Usually, CPUR^'s in the form of aqueous dispersions are used in surface sizing in which the sizing agent is applied to the paper surface at the size press.

U.S. Pat. No. 3,971,764 discloses high molecular weight CPUR sizing agents prepared by reacting a diol with a polyisocyanate to form a prepolymer with terminal isocyanate groups which is subsequently reacted with (a) a diol containing a tertiary nitrogen atom which is subsequently converted into the corresponding ammonium compound, or (b) a diol containing a nitrogen atom previously converted into the corresponding ammonium com¬ pound; method (a) being preferred. In these methods, the nitrogen atom can be rendered cationic by using an acid or alkylating agent and the patent discloses that hydrogen chloride, hydrochloric acid and dimethyl sulfate are useful for this purpose. Such CPUR dispersions generally provide good sizing response using low levels of sizing agent. It has, however, been observed that the CPUR dispersions exhibit stability problems and settling tendencies, in particular in the presence of electrolytes which are commonly added into the size press in order to prevent static electricity being built up during subsequent application, drying or con¬ verting processes. The insufficient stability may cause the CPUR particles contained in the dispersions to agglomerate and form deposits, leading to handling and application problems, deteriorated size performance and poorly sized paper.

According to the present invention it has been found that CPUR^'s having improved sizing and stability properties can be obtained by using in the polyurethane synthesis a hydroxy-functional quaternary ammonium compound (QUAT), i.e. an organic compound con¬ taining one or more hydroxyl groups and a positively charged quaternary nitrogen atom, in which the nitrogen has been quaternized with an epoxide. More specifically, the present invention relates to a method of producing a cationic polyurethane which comprises reacting a dihydroxy compound with a polyisocyanate to form a pre-polymer with terminal isocyanate groups which is then reacted with a hydroxy-functional quaternary ammonium compound containing a quaternary nitrogen that has a substituent derived from an epoxide. The invention thus relates to a method of producing cationic polyurethanes, to cationic polyurethanes per se and to their use, as further defined in the claims. The method according to the present invention leads to high molecular weight CPUR^'s with outstanding properties Aqueous dispersions of the present CPUR's exhibit improved stability and hereby the problems associated with pπor art sizing dispersions based on CPUR can be reduced or overcome The present CPUR dispersions further provide improved sizing which means that lower levels of sizing agent can be used to give the same sizing effect, thereby leading to cost reduction and economic benefits

Dihydroxy compounds, or diols, that can be used as monomers in order to form the prepolymer, or intermediate product, according to the present invention include aliphatic and aromatic diols The term "aliphatic", as used herein, refers to an essentially hydrocarbon structure apart from designated functional groups, which hydrocarbon structure may be inter¬ rupted by one or more heteroatoms, e g oxygen and nitrogen, and/or one or more groups containing heteroatoms, e g carbonyl and acyloxy groups The term "aromatic", as used herein, refers to an aromatic, essentially hydrocarbon structure apart from designated func¬ tional groups, which hydrocarbon structure may be interrupted by one or more heteroatoms, e g oxygen and nitrogen, and/or one or more groups containing heteroatoms, e g carbonyl and acyloxy groups It is generally preferred to use aliphatic diols and preferably such diols which have an aliphatic side-chain substituent which can contain from 1 to 30 suitably at least 5, preferably at least 10 and most preferably from 10 to 22 carbon atoms The diols may be high molecular weight polymeric compounds such as polyester, polyether and polybuta- diene diols, although it is generally more preferred to use non-polymenc aliphatic dihydroxy compounds which suitably contain from 2 to 20 and preferably from 2 to 10 carbon atoms in the chain connecting the two hydroxyl groups, i e in the main chain Preferred aliphatic main chains include alkylenes and dialkyleneamines containing from 2 to 10 carbon atoms Suitably the mam chain is substituted with an aliphatic side-chain as described above, where the mam chain contains a heteroatom which is nitrogen, it is preferred that the nitrogen carnes the side-chain Examples of suitable aliphatic dihydroxy compounds include ethylene and diethylene glycols, propane and butane diols, and higher molecular weight compounds such as fatty acid monoesters of tnols such as glycerol and tπmethylolpropane, e g glycerol monostearate and glycerol monobehenate, tπmethylolpropane monostearate, ohgomeπc esterdiols such as diester diols, e g those obtained by reacting a dicarboxylic acid, e g adipic acid, with a molar excess of a diol, e g ethylene glycols, N-alkyl-diethanoiamines, e g N-stearyl-diethanolamine, branched chain dihydroxy alkylenes, e g 1 ,2- and 1 ,4-dιhydroxy- octadecanes The higher molecular weight compounds are generally preferred, especially glycerol monostearate Examples of aromatic diols that can be used include bisphenol A Mixtures comprising one or more diols, such as any of those mentioned above, can also be used in the reaction with polyisocyanates Polyisocyanates that can be used as monomers to form the prepolymer in this method include aliphatic, aromatic and mixed aliphatic/aromatic compounds Among the polyisocyanates, it is preferred to use dnsocyanates Where polyisocyanates containing more than two isocyanate groups are used, e g tπisocyanates, it is preferred to admix them with diisocyanates Generally, polyisocyanates are known in the art, for example as disclosed in Encyclopedia of Polymer Science and Engineenng, Vol 13, Second Ed , 1988, pp 243-303, which is hereby incorporated herein by reference. Examples of suitable diisocyanates include toluene-2,4- and 2,6-dιιsocyanates, dιphenylmethane-4,4'-dιιsocyanate, hexamethylene dnso- cyanate, dιcyclohexylmethane-4,4'-dιιsocyanate, cyclohexane-1 ,4-dιιsocyanate isophorone dnsocyanate and the like It is also possible to use blocked isocyanates in known manner

The reaction of the monomeπc dihydroxy compound with the polyisocyanate can be canned out in conventional manner, for example as disclosed in U S Pat No 3,971 ,764, which is hereby incorporated herein by reference As isocyanates are susceptible to nucleo- philic attack and readily react with water, the prepolymer as well as the CPUR are preferably prepared in a reaction medium free from water and undesired nucloephiles Suitably the reaction is earned out in a water-free inert organic solvent, e g acetone, optionally in the presence of a catalyst, e g diacetoxy-dibutyi-tin The molar ratio of dihydroxy compound to polyisocyanate can be vaned over a broad range and in most cases the molar ratio is within the range of from 1 1 1 to 1 3, suitably from 1 1 5 to 1 2.5 and preferably about 1 2 Preferably the hydroxyl- and isocyanate-containing reactants used in the first stage are uncharged which thus leads to an uncharged prepolymer

The pre-polymer having terminal isocyanate groups obtained in the first stage of the method is then further reacted in a second stage with a hydroxyl-containing quaternary ammonium compound in order to introduce positive charges into the polyurethane The second stage can be carried out generally as taught in U S Pat No 3,971,764 except that in the present method there is used a hydroxy-functional QUAT containing a quaternary nitrogen atom having a substituent derived from an epoxy-functional quaterπiziπg agent Suitable hydroxy-functional QUAT^'s include compounds obtained by reacting a tertiary amine, suitably a hydroxyl-containing tertiary amine, with an epoxide, e g an alkylene oxide such as ethylene oxide and propylene oxide or, suitably, a halogen-containing epoxide such as epihaiohydπn, e g epichlorohydπn and epibromohydπn, preferably epichlorohydπn, and optionally with an acid In a preferred embodiment of this invention, the hydroxy-functional QUAT is a compound containing one or more hydroxyl groups and a quaternary nitrogen atom having a substituent derived from a halogen-containing epoxide and having an anion derived from an acid Suitable QUAT^'s for use according to the invention can thus be represented by the general formula (I)

Rt X^" (I)

R₂_ N⁺ — R₄

wherein R-, and R₃ are each independently selected from aliphatic groups containing 1-10 and preferably 1-4 carbon atoms, which may be substituted with hydroxy, suitable at least one hydroxyl group is present in R^ and/or R₃ and preferably R, and/or R₃ are linear or branched N-alkanols, e.g. N-ethanol; R₂ is an aliphatic group, suitably alkyl, containing 1-22 and preferably 1-4 carbon atoms, preferably methyl, ethyl, propyl or butyl, or alternatively R^ and R₂ together with N form a linear or branched 5 to 7 membered nng, preferably aliphatic, which may be substituted with hydroxy and one or two carbon atoms may be substituted with NR₅Re in which R₅ and R_β are aliphatic groups, preferably alkyl, containing 1-4 carbon atoms, R₄ is deπved from an epoxide, e.g. an alkylene oxide such as ethylene oxide and propylene oxide, or, suitably, a halogen-containing epoxide, preferably epichlorohydπn, and X is an anion of an acid In most cases, R^ R₂, R₃ and N of the QUAT are derived from a tertiary amine Generally, at least one hydroxyl group present in the QUAT is located on the substituent denved from the epoxide as quaternization of a tertiary amine by means of an epoxide normally leads to πng-opening of the epoxide group and formation of a hydroxyl group Suitable QUAT^'s include those descπbed in EP 541289 which is incorporated herein by reference for all purposes. The R₄ substituent can thus be represented by the general formula (II) derived from an epoxide of the general formula (III)-

— R₇HC — CH — R₈ (II) R₇HC — CH — R₈ (III)

I \ / OH O wherein R₇ is hydrogen or an aliphatic group such as alkyl, preferably hydrogen; and R₈ is hydrogen or an aliphatic or aromatic group which can contain up to 20 carbon atoms, e g alkyl such as methyl, and which can be substituted with halogen; R₈ suitably being a halogen- containing aromatic or aliphatic group, preferably aliphatic, which may contain from 1 to 12 carbon atoms, preferably the halogen is chloπne and R₈ is CH₂ — Cl In addition, in QUAT^'s obtained by reacting a tertiary amine with an epoxide of formula (III) where R₇ = H and R₈ = H or alkyl such as methyl, i e an alkylene oxide, the R₄ substituent of the resulting QUAT of formula (I) may be a linear or branched hydrocarbon chain interrupted by one or more oxygen atoms, i e a di- or polyalkyleneoxy group, and containing a hydroxyl group, usually in a terminal position since the quaternization reaction may lead to di- or polyaddition of alkylene oxides

The reaction between the prepolymer and QUAT, i e the reaction between isocyanate groups(s) of the prepolymer and hydroxyl group(s) of the QUAT, leads to chain- lengthening of the polyurethane As will be appreciated, the degree of chain-lengthening depends on the number of reactive hydroxyl groups present in the QUAT where a mono- hydroxy-functional QUAT will act as a chain-term mator and thus provide less chain-lengthen¬ ing The QUAT used, e g. the QUAT of formula (I), contains one or more hydroxyl groups and in most cases not more than 4 such groups, suitably from 1 to 3 hydroxyl groups and preferably 2 or 3 Mixtures containing more than one QUAT can of course be used If desired, the QUAT can be used in combination with an additional hydroxy-functional com¬ pound, such as any of the hydroxytic compounds mentioned herein In many cases, the use of admixtures containing QUAT and additional hydroxyhc compound is preferred, for example where the QUAT exhibits limited solubility in the reaction medium used Preferred additional hydroxyhc compounds include the diols and hydroxy-functional tertiary amines described herein In a preferred embodiment, use is made of a composition containing QUAT and a hydroxy-functional tertiary amine, suitably the same type of amine used to prepare the QUAT The molar ratio of QUAT to additional hydroxyhc compound, when used, can be vaπed over a broad range depending on, among other things, the isocyanate content in the prepolymer, the desired QUAT content and cationicity of the CPUR and the intended use of the CPUR Usually, this molar ratio can be from 50 1 to 1.100 The molar ratio of hydroxyl groups to isocyanate groups in the second stage can be vaπed over a broad range and in most cases the molar ratio is within the range of from 1 0 5 to 1 2, suitably from 1 0 8 to 1 1 4 and preferably about 1 1 The CPUR obtained may have an average molecular weight of at least 1,000, suitably at least 3,500 and preferably at least 4,000 The upper limit of molecular weight is not cπtical, usually it is about 30,000 and preferably about 15,000 After completed reaction the reaction mixture containing CPUR can be worked-up and converted into an aqueous dispersion in conventional manner, for example as disclosed in U S Pat Nos 3,971 ,764 and 4,617,341 Examples of useful steps include addition of acid, addition of water, evaporation of solvent and the like In a preferred aspect of the process, an acid is added to accomplish neutralization by converting any tertiary nitrogen atoms present in the CPUR into the corresponding tertiary nitrogen acid addition salt

The present invention further relates to an aqueous dispersion comprising the CPUR, to its use as a sizing agent in the making of paper and similar cellulose based products like board and paper board, wherein the aqueous CPUR dispersion is added to the papermaking stock or applied to the surface of said products preferably to surface size such products The amount of CPUR dispersion added to the stock or applied to the surface of cellulosic products may be from 0 001 to 20% by weight, calculated as dry CPUR on dry cellulose based mateπal and optional filler, suitably from 0 01 to 2% by weight The CPUR dispersions may contain from about 1 to 50% by weight of CPUR, suitably from 5 to 25% by weight The CPUR dispersions may of course be diluted with water prior to being used as sizing agents

The present invention further relates to certain hydroxy-functional QUAT's More specifically, the invention relates to quaternary ammonium compounds containing one or more hydroxyl groups and a quaternary nitrogen atom having a substituent derived from a halogen-containing epoxide and having an anion derived from an acid, compositions comprising such QUAT^'s, their preparation and use, as further defined in the claims

The QUAT according to the invention, which contains a positively charged nitrogen attaching four radicals or substituents, can be represented by the general formula (I) defined above wherein R₄ is derived from a halogen-containing epoxide, preferably epichlorohydnn The QUAT contains one or more hydroxyl groups and in most cases not more than 4 hyd¬ roxyl groups, preferably from 1 to 3 and more preferably 2 or 3 hydroxyl groups, which can be located on any of the substituents connected to the nitrogen

The anionic part of the QUAT of formula (I), i e X^", is the anion of an acid, prefer- ably a protonic acid such as HX, including organic acids, e g formic acid acetic acid, propionic acid, methane sulfonic acid and p-toluene sulfonic acid, and inorganic acids, e g hydrogen hahdes and sulfuπc acid In a preferred embodiment, X is the anion of an organic acid and, in particular, formic acid

Hydroxy-functional QUAT^'s of this invention can be prepared by reacting a tertiary amine with a halogen-containing epoxide in the presence of an acid The reaction can be carried out using water as a solvent although it has been found, in accordance with the present invention, that hydroxy-functional QUAT^'s can be prepared in high yield in a very advantageous manner by reacting these reactants in the substantial absence of water The method renders possible production of a wide range of hydroxy-functional QUAT's containing different N-substituents and counter-ions Furthermore, after completed reaction, the reaction mixture obtained contains essentially no or very low amounts of ohgomeπc material and/or undesired by-products whereby the QUAT obtained can be used in the CPUR synthesis without costly purification The QUAT obtained in the method also exhibit good stability The subject method thus offers substantial technical and economic benefits Generally, it is common to use water as a solvent in the reaction and/or in the work- up when preparing quaternary ammonium compounds Water, being a polar solvent normally favours the formation of charged reaction products like QUAT^'s and facilitates separation of the QUAT from the reaction mixture by means of extraction using water in conjunction with a water-immiscible solvent However monomers to be used in CPUR production should suitably be free from water since isocyanates are susceptible to nucleophilic attack It has been experienced that extensively removing water from hydroxy- functional quaternary ammonium salts is complicated, costly and may lead to decomposition of the QUAT Therefore, by providing a reaction which is carried out in the substantial absence of water, there is produced a QUAT especially useful for subsequent conversion with isocyanates into cationic polyurethanes The tertiary amine used in the present method is an organic compound containing at least one quaternizable tertiary nitrogen atom Suitably the tertiary amine in an aliphatic amine The tertiary amine suitably contain from 3 up to 25 carbon atoms, preferably from 4 to 10 Suitable tertiary amines can be represented the general formula (IV)

R, (IV)

I R₂— N

R₃ wherein R-i, R₂, and R₃ are as defined above The tertiary amine suitably contains from 0 to 3 hydroxyl groups and preferably 1 or 2 hydroxyl groups

Examples of useful tertiary amines include non-hydroxylic amines such as N-tπalkyl- amines, monohydroxy amines such as N,N-dιalkyl alkanolamines, and dihydroxy amines such as N-alkandiol dialkylamines and N-alkyl dialkanolamines Suitable tertiary amines include tπethylamine, N,N-dιmethyl stearylamine, N,N-dιmethyl ethanolamme, 1 ,2-propane- dιol-3-dιmethylamιne, N-methyl diethanolamine, N-ethyl diethanolamine, N-propyl diethanol- amine, N-n- and N-t-butyl diethanolamines, N-stearyl diethanolamine and N-methyl dipropa- nolamine N-alkyl dialkanolamines and N,N-dιalkyl alkanolamines, such as for example N- alkyl diethanolamines and N,N-dιalkyl ethanolamines, in which the alkyl groups contain 1 to 4 carbon atoms are preferred, in particular N-methyl diethanolamine and N,N-dιmethyl ethanol¬ amme

The epoxide in the present method is an organic compound capable of functioning as a quatemizing agent and contains at least one epoxide, or oxirane, group, and at least one halogen atom Monoepoxy- and monohalogen-functional compounds are preferred Suitable halogen-containing epoxides include compounds of the formula (III) defined above, preferably epichlorohydπn, which when being reacted with the amine and the acid forms the substituent of formula (II) connected to the nitrogen Suitable acids include protonic acids, HX, which forms the anion X^" of the QUAT. Preferably the acid is one that can be supplied as a substantially water-free acid. Examples of suitable acid include organic acids such as formic acid, acetic acid, propionic acid, methane sulfonic acid and p-toluene sulfonic acid as well as inorganic acids such as hydrogen chloride, hydrogen bromide and sulfuric acid. In a preferred embodiment of the invention, use is made of organic acids and, in particular, formic acid.

It has been found that the acid has an important role in the reaction and that higher levels of oligomeric material are usually formed when the reaction between the tertiary nitro¬ gen and epoxide takes place in the absence of acid. When carrying out the reaction, the acid should suitably be present in an amount so that the reaction mixture has a pH of at least 7 and suitably a pH within the range of from 7 to 13. The pH of the reaction mixture can be measured in known manner, for example with a pH meter or pH electrode. It is preferred that at least part of the acid is present when bringing the amine into contact with the epoxide. Hereby the tertiary amine, or part thereof, may be present in the form of tertiary amine acid addition salt, e.g. R₁R₂R₃N H X^", wherein R,, R₂, R₃, and X are as defined above. In a prefer¬ red embodiment of the invention, the acid is intermittently or continuously fed to the reaction mixture so as to keep the pH within the desired range. Preferably, the pH value is between 7 and 12 and most preferably between 8 and 10.

In the method, the molar ratio of tertiary nitrogen to epoxide usually is at least 0.4:1, suitably at least 0.6:1 , preferably at least 0.8:1. The upper limit for the molar ratio tertiary amine to epoxide can be high, for example 15:1 or higher, in many cases 10:1 , usually 5:1 , suitably 1.4:1 and preferably 1.2:1. In the method, the molar ratio of acid to epoxide can be varied over a broad range depending on, among other thing, the desired pH of the reaction mixture during the reaction. Suitably the reaction is carried out with the acid and epoxide in approximately equimolar amounts or with a molar excess of the acid. For instance, a molar excess of up to about 30% may be beneficial in terms of product stability.

The reaction can be carried out neat, i.e., in the absence of a solvent, or in the presence of a solvent. In a preferred aspect of the invention the reaction is carried out in the absence of inert organic solvents. Where solvents are used, it is preferred to use inert organic polar solvents. Suitable solvents include dimethylformamide, pyrrolidone, hexa- methylene phosphortriamide and the like. It is further possible to use protic solvents such as alcohols, e.g. methanol, ethanol, isopropanol and the like. However, in cases where the QUAT is to be used in the production of CPUR^'s, protic solvents are preferably removed from the QUAT prior to use since protic solvents readily react with isocyanates. Therefore, if used, the solvent preferably is a non-protic solvent. Appropriate amounts of solvent to be used can easily be determined by the skilled person through routine experimentation. The present method should be earned out in the substantial absence of water Hereby is meant that the amount of water present dunng the reaction and work-up should be low, for example below 15% by weight, suitably below 5% by weight and preferably below 3% by weight, based on the weight of reactants. In a most preferred aspect of the invention, no water at all is present. The reaction can be run at a temperature below 50°C, suitably below 35°C and preferably below 25"C. The lower limit is not crucial and the reaction can be earned out at a temperature above -80^βC, suitably above -25°C and preferably above 0"C. It may be advantageous to cool the reaction mixture dunng the reaction, especially when admixing the reactants. In another aspect of this invention there is provided a method of producing a hydroxy-functional quaternary ammonium compound useful in the CPUR production which compπses reacting a tertiary amine with an epoxide in the presence of an acid and in the substantial absence of water and organic solvents. The tertiary amine and the acid can be as defined above and the epoxide is an organic compound capable of functioning as a quater- nizmg agent containing at least one epoxide, or oxirane, group, preferably having the general formula (III) above. The reaction is earned out in the substantial absence of water and organic solvents and hereby is meant that the amount of water and organic solvents, e.g. any of those defined above, should be low, for example in amounts defined above with respect to water but in this aspect meaning to the combined weight of water and organic solvent. After completed reaction, the pH of the reaction mixture can be adjusted to 4-9 for the purpose of improving the stability of the QUAT, suitably to pH 5-8 and preferably to pH 6- 7. This may be accomplished by means of any acid that is essentially water-free, e.g. any of those mentioned above. The solvent used in the reaction, if any, can be removed from the reaction mixture by evaporation, suitably at reduced pressure. The product formed can be used directly, for example in the production of CPUR's, without puπfication. If desired, the ammonium salt obtained may of course be subjected to any conventional purifiction step, e.g. extraction and crystallization in known manner.

The present method shows high selectivity and thus produces hydroxy-functional QUAT^'s in high yields with low or no formation of oligomeπc and polymeric material. Furthermore, where epichlorohydrin is used as a quaternrzmg agent to produce the QUAT, low levels of unreacted epichlorohydnn and undesired by-products such as 1-chloro-2,3- propane diol (CPD) and 1 ,3-dichloro-2-propaπol (DCP) are usually obtained. Generally, the conversion of epichlorohydrin to CPD is less than 5% and normally less than 3%, based on the weight of epichlorohydrin used in the reaction, and the conversion of epichlorohydπn to DCP is less than 1% and normally less than 0.1% by weight Accordingly, one of the advantages of using the QUAT^'s of this invention in CPUR production is that CPUR's and dispersions thereof can be provided with very low contents of unreacted halogen-containing epoxide, e g epichlorohydrin, and undesired by-products derived from the halogen-functional epoxide, e g CPD and DCP In the CPUR^'s and CPUR dispersions according to the invention, the amount of halogen-containing epoxide such as epichlorohydrin present can be less than 10 ppm, suitably less than 5 and preferably less than 1 ppm, calculated as halogen- containing epoxide and based on CPUR solids, and the amount of halogenated by-products can be less than 1 % by weight and suitably less than 0 5 % by weight, calculated as total amount of halogenated by-products and based on CPUR solids Notably, when using epichlorohydπn, the CPD content can be less than 0 1% by weight, suitably less than 0 05% by weight and preferably less than 10 ppm, based on CPUR solids, and the DCP content can be less than 0 5% by weight, suitably less than 0 1% by weight and preferably less than 10 ppm, based on CPUR solids

The invention further relates to a composition compπsing the present hydroxy-func¬ tional quaternary ammonium compound, as further defined in the claims The composition is substantially free from water, as defined above In addition to the QUAT, the composition can for example contain unreacted starting mateπals such as any of those used in the reaction, e g any material used in excess, and minor amounts of reaction-typical by-products The composition may also contain additional compounds admixed with the composition Examples of such additional compounds include acids and tertiary amines, e g any of those defined herein In a preferred embodiment, the QUAT is present in the composition in a pre¬ dominant amount, based on weight, i e , the weight ratio of QUAT to each of the other components present in the composition is higher than 1 In another preferred embodiment, a hydroxy-functional tertiary amine and/or its acid addition salt is present in the composition in a predominant amount, based on weight, preferably the tertiary amine Such compositions are particularly useful in the preparation of CPUR The tertiary amines and acids for formation of the acid addition salt may be any of those defined herein and suitably the same type of compounds used as reactants in the method of the invention

The invention is further illustrated in the following Examples which, however, are not intended to limit same Parts and percentages relate to parts by weight and percent by weight, respectively, unless otherwise stated

Example 1

In accordance with the present invention, (3-chloro-2-hydroxypropyl)-bιs(2- hydroxyethyO-methylammonium formiate was prepared as follows To cooled 11 9 g (0 1 moles) of N-methyl diethanolamine, 98% concentrated formic acid was added with stirring to produce a pH of between 9 and 10, as measured by means of a pH electrode To this mixture was added 7 4 g (0 08 moles) of epichlorohydrin, and the reaction mixture was cooled so as to keep the temperature at ΣOX, and additional formic acid was continuously added to keep the pH between 9 and 10 After stirring for 10 hours pH was adjusted to 6 5 by addition of formic acid The desired product was formed in high yield, as shown by ¹³C-NMR and GPC, and the formation of by-products was low Essentially no ohgomeπc and polymeπc material was formed The product so obtained was stable for more than three months at room temterature

Example 2 The procedure of Example 1 was followed except that the amine used was N,N- dimethylethanolamme and that the amine and epichlorohydπn were used in equimolar amounts The desired product, (3-chloro-2-hydroxypropyl)-(2-hydroxyethyl)-dιmethyl- ammonium formiate, was obtained in high yield Only minor amounts of impurities were formed and there were essentially no formation of oligomeπc and polymeric material

Example 3 (Comparison)

The procedure of Example 1 was followed except that no acid was used in the method An exothermic reaction between N-methyl diethanolamine and epichlorohydrin took place which was very difficult to control and phase separation was observed, indicating formation of oligomeπc/polymeπc mateπal After two days the reaction mixture had been completely converted to a solid mass and no moπomeπc compounds could be detected

Example 4

A cationic polyurethane according to the invention was prepared as follows To a solution of 18 3 g of glycerol monostearate and 18 3 g of toluene dnsocyanate in 50 g of water-free acetone at a temperature of 40^βC was added 17 mg of dibutyl tin- diacetate in acetone The solution was refluxed for 1 hour under vigorous stirπng A sample of the solution was taken away for determination of residual NCO-groups and showed a residue of 14% A mixture of 5 1 g of N-methyl diethanolamine (N-MDEA) and 2 2 g of QUAT according to Example 1 , where the mixture had a molar ratio N-MDEA to QUAT of 5 1 , was added to the solution at 50^βC followed by addition of further 50 ml of acetone The mixture was refluxed for 1 hour and then 40 ml of 1 M HCI was added for neutralization and formation of tertiary amine acid addition salt and then the mixture was diluted with 250 ml of water Acetone was evaporated under reduced pressure at 60-70°C to afford a clear residue in the form of a dispersion containing approximately 15-17% of CPUR at pH 4 The contents of epichlorohydrin CPD and DCP were all below the detection limit of the gas chromatographic 7 7

12 method used; the epichlorohydπn content was below 1 ppm, the CPD and DCP contents were both below 10 ppm.

Example 5 A cationic polyurethane according to the invention was prepared as in Example 4 except that the molar ratio of N-MDEA to QUAT was 4 1

Example 6

A cationic polyurethane according to the invention was prepared as in Example 4 except that the molar ratio of N-MDEA to QUAT was 3:1 which thus corresponded to about 25% quaternization of the nitrogen atoms.

Example 7 (Compaπson)

In this test, a CPUR was prepared by reacting HCI with a polyurethane containing tertiary amine groups.

Glycerol monostearate was reacted with toluene dnsocyanate as in Example 2 and then the pre-polymer with terminal NCO-groups was reacted with solely N-methyl diethanol¬ amine The uncharged polyurethane was rendered cationic by addition of 1 M HCI which converted tertiary nitrogen atoms into the corresponding acid addition salt. Work-up was made as in Example 4 which yielded a dispersion containing about 15-16% of CPUR at pH 4

Example 8 (Comparison)

The procedure of Example 7 was followed up to the reaction with N-methyl diethanolamine. The polyurethane so formed was reacted with dimethyl sulfate to effect quaternization of about 25% of the nitrogen atoms and then 1 M HCI was added for neutralization The work-up was carried out as in Example 4 which resulted in a dispersion containing about 15% of CPUR at pH 4.

Example 9 Stability of the cationic polyurethane dispersions of Examples 4-8 was evaluated by adding a saturated aqueous solution of sodium sulfate to 100 ml of aqueous dispersion containing 0.5% by weight of cationic polyurethane The mixtures were stirred at 20^βC and then inspected visually. Table I shows the results. Table 1

Na₂S0₄(aq.) Appearance of Cationic Polyureth; ane Dispersion added (ml) Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8

0 Clear Clear Clear Clear Clear

1.0 Clear Clear Clear Precip Clear

2.0 Clear Clear Clear Precip S-Turb

3.0 Clear Clear Clear Precip S-Turb

4.0 - - S-Turb - V-Turb

5.0 - - S-Turb - Precip wherein S-Turb = slightly turbid V-Turb = very turbid Precip = precipitation = not analyzed As is evident from Table I, the dispersions of cationic polyurethane of Examples 4-6 according to the invention were considerably more stable than the polyurethane dispersions used for comparison purposes.

Example 1Q

Sizing efficiency of the CPUR dispersions according to Examples 4-7 was evaluated by means of the Cobb Test, using German DIN standard 53/32, which is conventional in the art. The Cobb-values correspond to paper absorption of water, expressed in g/m² of water take-up after contact for 1 minute. The values measured on the sized paper sheets are set forth in Table II, where dosage (%) refers to dry cationic polyurethane on dry sheet. Table II

Sizing agent Cobb-value ot itained using P< slyurethane Sizing Dis dosaqe (%) Ex. 4 Ex, 5 Ex, 6 Ex, 7

0.075 80 80 74

0.10 40 36 36 74

0.15 22 21 23 29

0.20 - - 22

As can be seen from Table II, the sizing agents of Examples 4 to 6 according to the invention showed markedly improved sizing efficiency over the sizing agent of Example 7 used for comparison.

Claims

1 A method of producing a cationic polyurethane, characterised in that it comprises

(a) reacting a dihydroxy compound with a polyisocyanate to form a pre-polymer having terminal isocyanate groups,

(b) reacting the pre-polymer with a hydroxy-functional quaternary ammonium compound containing a quaternary nitrogen having a substituent deπved from an epoxide

2 A method according to claim 1, characterised in that the hydroxy- functional quaternary ammonium compound contains a quaternary nitrogen having a substituent denved from a halogen-containing epoxide

3 A method according to claim 1 or 2, characterised in that the quaternary ammonium compound contains from 1 to 3 hydroxyl groups and a quaternary nitrogen having a substituent derived from epichlorohydrin and has an anion derived from an acid

4 A method according to claim 1, 2 or 3, characterised in that the quaternary ammonium compound has general formula (I)

Rt X^" (I)

.+

R₂— N — R₄

wherein R, and R₃ independently are selected from aliphatic groups containing 1-4 carbon atoms which may be substituted with hydroxy, at least one hydroxyl group being present in Ri and/or R₃, R₂ is an alkyl group containing 1-4 carbon atoms, R₄ is derived from epichlorohydrin and X is an anion of an acid

5 A method according to claim 1, 2, 3 or 4, characterised in that the quaternary ammonium compound has an anion of an organic acid.

6. A method according to any of the preceding claims, characterised in that the dihydroxy compound comprises an aliphatic compound substituted with an aliphatic side- chain containing at least 5 carbon atoms

7 A method according to any of the preceding claims, characterised in that the dihydroxy compound comprises an aliphatic compound containing from 2 to 10 carbon atoms in a mam chain connecting the two hydroxyl groups, the main chain being substituted with an aliphatic side-chain containing at least 10 carbon atoms

8 A method according to any of the preceding claims, characterised in that the polyisocyanate comprises toluene dnsocyanate 9. A method according to any of the preceding claims, c h a r a c t e r i s e d in that the cationic polyurethane formed has a molecular weight of at least 3500.

10. A cationic polyurethane obtainable by a method according to any of claims 1 to 9. 11. An aqueous dispersion comprising a cationic polyurethane according to claim

10.

12. An aqueous dispersion according to claim 11, c h a r a c t e r i s e d in that the content of epichlorohydrin is less than 10 ppm, based on cationic polyurethane solids.

13. An aqueous dispersion according to claim 11 or 12, c h a r a c t e r i s e d in that the content of 1-chloro-2,3-propane diol (CPD) is less than 0.05% by weight, based on cationic polyurethane solids, and the content of 1,3-dichloro-2-propanol (DCP) is less than 0.1% by weight, based on cationic polyurethane solids.

14. Use of an aqueous dispersion comprising a cationic polyurethane according to claim 11, 12 or 13 as a sizing agent for cellulose based products. 15. A hydroxy-functional quaternary ammonium compound containing one or more hydroxyl groups and a quaternary nitrogen having a substituent derived from a halogen- containing epoxide and having an anion derived from an acid, with the proviso that the anion is not chloride.

16. A quaternary ammonium compound according to claim 15 having the general formula (I):

Rt X^' (I)

.+

R₂_ N — R₄

wherein Rt and R₃ independently are selected from aliphatic groups containing 1-4 carbon atoms which may be substituted with hydroxy, at least one hydroxyl group being present in Ri and/or R₃; R₂ is an alkyl group containing 1-4 carbon atoms; R₄ is derived from epichlorohydrin and X is an anion of an acid.

17. A quaternary ammonium compound according to claim 15 or 16 having an anion of an organic acid.

18. A substantially water-free composition comprising a quaternary ammonium compound according to any of claims 15 to 17 and a hydroxyl-containing tertiary amine and/or an acid addition salt thereof. 19 A composition according to claim 18, c h a r a c t e r i s e d in that the hydroxyl- containing tertiary amine and/or acid addition salt thereof is present in a predominant amount, based on weight

20 A method of producing a hydroxy-functional quaternary ammonium compound by reacting a tertiary amine with a halogen-containing epoxide in the presence of an acid and in the substantial absence of water.

21. A method of producing a hydroxy-functional quatemary ammonium compound by reacting a tertiary amine with an epoxide in the presence of an acid and in the substantial absence of water and organic solvents 22. A method according to claim 20 or 21, c h a r a c t e r i s e d in that the tertiary amine being reacted with the epoxide and the acid is N-alkyl diethanolamine or N,N-dιalkyl ethanolamine in which the alkyl groups contains from 1 to 4 carbon atoms

23. A method according to claim 20, 21 or 22, c h a r a c t e r i s e d in that that the acid is formic acid, acetic acid, propionic acid, methane sulfonic acid, p-toluene sulfonic acid, hydrogen chloride, hydrogen bromide or sulfuπc acid.

24 A method according to any of claims 20 to 23, c h a r a c t e r i s e d in that that the epoxide is epichlorohydπn

25 A method according to any of claims 20 to 23, c h a r a c t e r i s e d in that that the epoxide is ethylene oxide or propylene oxide 26. A method according to any of claims 20 to 25, c h a r a c t e r i s e d in that at least part of the acid is present when bπnging the amine into contact with the epoxide and that additional acid is intermittently or continuously fed to the reaction mixture during the reaction

27 Use of a hydroxy-functional quaternary ammonium compound according to any of claims 15 to 17 or a composition compπsing a hydroxy-functional quaternary ammonium compound according to claim 18 or 19 for the production of a cationic polyurethane