CA2121959A1 - Use of an aqueous polyurethane dispersion as an adhesive - Google Patents

Abstract

Abstract of the Disclosure: Aqueous dispersions contain-ing a polyurethane which in essentially composed of a) organic polyisocyanates, b) polyhydroxy compounds having a molecular weight of from above 500 to 5,000 g/mol, c) compounds having at least one group reactive toward isocyanate and having at least one ionic group or group convertible into an ionic group and d) if required, compounds which differ from (c) and have at least two functional groups reactive toward isocyanate and a molecular weight of from 60 to 500 g/mol, and at least one chelate complex comprising a polyvalent metal as the central atom and a polydentate ligand are used as an adhesive.

Description

~ 212~9~
O.Z. 0050/44008 Use of an aq~eou~ polYurethane disPer~ion a~ an adhesive The pre~ent invention relates to the use of an aqueous polyurethane disper~ion a~ an adhesive. In order to avoid Rolvent wa3tes and solvent emis~ions, aqu ous polymer disper~ions, in particular polyurethane disper-sions, are increasingly being used a~ adhesives. Poly-urethane di~persion~ are described in, for example, DE-A-39 03 538 and DE-A-14 95 745. Sinco the mechanical properties, in particular the heat di~tortion re~istance, of adheeive bonds obtainable with such di~persions are often inad~quats, they are cros~linked, for example by adding polyiYocyanate~, a~ de~aribed in, for example, EP-A-02 08 059 and ~S-A-47 62 880. However, thi~ type o~
cros~linking has the di~advantage that the pot life, ie.
th~ time which ramains for proce~ing after the addition of the cro~sli~king ageut, i8 vsry ~hort.
The cros~linking o~ polyurethane di0per~ion~ by means of polyvalent metal comploxe~ i~ di~clo~ed in EP-A
228 481, which r~latea to ramovable floor coatings.
The unpubliehod German Patont Application P 4137556.4 di~close~ polyurethane di~p~rsions which contain an adheeion-improving polymer and inorganic salts.
It ie an obj~ct of th~ ~reeent invention to improve the mechanical propertie~, in particular the heat di~tortion resietance, when polyur~thane di~persion~ are u~ed a~ an adhesive.
We ha~ found that thi~ object ie achieved by th~
use of aqueou~ di~per~ione, containing a polyurethane which i~ essentially compo~ed of a) organic polyiaocyanatas, b) polyhydroxy compound~ having a molecular weight of from above 500 to 5,000 g/mol, c) compou~ds having at- leaBt one group reactive toward ieocyanate and having at leaet on~ ionic group or group con~ertible into an io~ic group and ; ~ , . .. .

2~21g~9 2 - O.Z. 0050/44008 d) if required, compounds which differ from (c) and ha~e at least two functional groups reactive toward i~ocyanate and a molecular weight of from 60 to 500 g/mol, and at least one chelate complex comprining a poly~alent metal as tha central atom and a polydentate ligand, as an adhe~ive. We have al~o found aqueous dispersions which are auitable for u~e as an adhesive.
The polyurethane i~ e~sentially, preferably exclusi~ely, compo~ed of the componant~ a-d). The functional groups reaative toward i~ocyanate are hydroxyl or primary or secondary amino group~
Suitable polyi~ocyanats3 (a) are in particular aliphatic, cycloaliphatic and aromatic dii~ocyanates.
1~ Tho~e of the general formula X(NC0) 2~ where X is an aliphatic hydrocarbon radical of 4 to 12 carbon atomn or a cycloaliphatic or aromatic hydrocarbon radical of 6 to 15 carbon atoms, are pr~ferably u0ed.
Example~ of suitabl~ aliphatic, cycloaliphatic and aromatic diiaocyanates are butane 1,4-dii30cyanate, hexane 1,6-dii~ocy~nate, 2,2,4- and 2,4,4-trimethyl-hexamethylene diisocyanate, cyclohexa~e dii~ocyanate, methylcyclohexane diisocyanate, isophorone dli~ocya~ate, 4,4'-diisocyanatodiphenylmethane, 4,4'-diisocyanato~
dicyclohe~ylmOEthane, toluylene 2,4- and 2,6-dii0ocyanats and tetramathylxylylene dii~ocyanato (TMXDI).
Mixture~ of the dii30cyanate~ may al80 be u~ed.
Mixtures o~ aliphatic or cycloaliphatic dii~ocyanate~
with aromatic diisocyanates in a molar ratio of from 1 : 4 to 5 : 1 have pro~en particularly ~uitable.
In addition to the dii30cyanates, it i8 al~o po~sible to uae minor amount~ of monoiaocyanates for molecular weight regulation.
Compound having more than 2 isocyanate group~, such as bluret~ or i~ocyanuratee, or example those of iaophorone diisocyanate or hexamethylene 1,6-diiaocyanate, may also be pre~ent.

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` 21219~9 ,~ ~
_ 3 _ o.Z. 0050/44008 Suitable polyhydroxy compounds, in partiaular dihydroxy compound~ (b), having a molecular weight of from abo~ 500 to 5,000 are the known polyesters, poly-etherEi, polythioethers, polylactone~, polyacetals, poly-carbonate~ and polyesteramide~ having 2 hydroxyl groups.Preferred dihydroxy compounds are those who~e molecular weight i3 ~rom 750 to 3,000. Mixturo~ of these dihydroxy compounds can of course al~o be u~ed.
If nece0sary, compounds with more than 2 hydroxyl group~, for example glycerol or trimethylolpropana alkoxylated with polypropylene oxide, may additionally be used.
Example~ o~ ~uitabls components (c) which di~er from (b) are aliphatic, cycloaliphatic or aromatic mono-or dihydroxycarboxylic acid~. Dihydroxyalkanecarboxylic acids, in particular of 3 to 10 carbon atom~, as al o de~cribed in US-A-3 412 0S4 are preferred. Compound~ o~
the general formula COO
HO~ R2 - C - R3 - OH

R~

whero Rl iB hydrogen or alkyl o 1 to 4 aarbon atom~ and Rl and R3 are each Cl-C~-alkylene, are particularly prerer-red. ~n ex~mple i~ 2,2-dimethylolpropionic acid.
Tertiary ammonium ~alt~ containing one or two hydroxyl or amino groups and aminocarboxylic acids or amino~ulo~ic acids, for example ly~ina, alanine, N-(2-aminoethyl)-2-aminoethane~ulfonic acid and the adduct~ of aliphatic d~pximary diaminer~ with ~-ole~inic carboxylic acid~, di~clo~ed in DE-A-20 34 479, for example the adduct o~ ethylenediamine with acrylic aoid, are alr~o noteworthy.
Component (c) contains ion~c group~ or groups convertible into ionic group~i, in order to en~ure tho .,.: :.

2~21~9 - 4 - O.Z. 0050/44008 di~persibility of the polyurethane in water. Its content is u~ually from 0.03 to 0.5, preferably ~rom 0.05 to 0.4, gram equivalent, based on 1 mol of i~ocyanate group~.
Inorganic and/or organic bas~, such as ~odium hydroxide, potaa~ium hydroxide, potassium carbonate, sodium bicarbonate, ammonia or primary, 3econdary and in particular t~rtiary aminQs, eg. triethylamine or dimethylaminopropanol, can be used for con~erting pote~tial anionic group0, for example carboxyl groupa or sulfQ groups, into ionic groups.
For the con~er~ion o~ the potential cationic groups, for example the tertiary amino group~, into the corresponding cations, for example ammoni~m group~
inorganic or organic acid~, for ~xample hydrochloric acid, acetic acid, fumaric acid, maleic acid, lactic acid, tartaric acid, oxalia acid or pho~phoric acid are ~uitable a~ neutralizing agents or, for example, methyl chloride, methyl iodide, dimethyl sulfate, benzyl chloride, ethyl chloroacetate or bromoacetamide are suitable a~ quaternizing agent~. Further suitable neutralizing and quaternizing agents are de3cribed in, $or example, U.S. Patent 3,479,310, column 6.
The neutralization or quaternization o the ionic or o~ the potentially io~ic group~ ca~ be carried out be~ore, durins and in particular after tha isocyanate polyaddition reaction.
I~ nece~sary, nonionic emul~i4i0rs, ~uch a~
monohydr~c polyether alcohols having a molecular weight of from 500 to 10,000, preferably rom 1,000 to 5,000, g/mol may also be present. ~owever, t~e use of nonionic emulsi~ier~ i8 generally not ne~essa~y, owing to the pre~ence o~ compound~ c).
Component3 d) are e~entlally compounda which contain two hydroxyl group~, two amino group~ or one hydroxyl and ona amino group. For example, dihydroxy compounds, such a~ 1,3-propansdiol or 1,4-butanediol, diamines, ~uch a~ ethylenediamine, hexa~ethylenediamine, -` 21219~
- 5 - o.Z. 0050/44008 piperazine, 2,5-dimethylpiperazine, ~-amino-3-amino-methyl-3,5,5-trimethylcyclohexane (isophoronediamine), 4,4'-diaminodicyclohexylmethane, 2,4-diaminocyclohexane, 1,2-diaminopropane or hydrazi~e, or amino alcohols, ~uch 5 a3 ethanolamine, i~opropanolamine, methylathanolamine or aminoethoxyethanol, are ~uitable.
Compou~ds having at least 3 groupR reactive toward isocyanate may al80 be suitable, for example -- triols, auch as trimethylolpropane or glyc~rol, or tri-hydroxy aompounds havi~g ether or est~r groups, aB well a3 pentaerythritol aa a tetrahydroxy co~pound, triamine compounds, ~uch a~ diethylenetriamine, 4-aminomethyl-octanediamin~ or trisaminoethylamine, and compound3 containing hydroxyl and amino groups, Quch as diethanolamine.
The total content of the components ia preferably chosen 80 that the sum of the hydroxyl and primary or ~econdary amino groups reacti~e toward iaocyanate i8 from 0.9 to 1.3, particularly preferably from 0.95 to 1.1, based on 1 isocyanata group.
For the preparation of the polyurethane, the component~ a) to d) can be reacted in a known manner in a low-bolling, water-mi~cible, organic solvent or in the ab~ence o4 ~olvents, a~ al80 described in DE-A-34 37 918.
A11 solvents whi~h are unreactive toward iso-cyanate may ba used a~ the ~ol~ent. Tho~e which are infinitely mi~ible with water, for example tetrahydro~
~uran, methyl ethyl k~tone, N-methylpyrrolidone and in particular acetone, ara particularly preferred. ~igh-boiling, water-miacible sol~ents, ~or example N-methyl-pyrrolidon2 or dimethylformamide, are less preferable.
Water-immis~ible ~olventR, ~or ~xample toluene or xylene, may al~o be present in minor amount~. The boiling point o~ the sol~ent i8 pra~erably below 100C.
The reaction tempera~ure is preferably from 50 to 120C.
Con~entional and k~ow~ cataly8t8, BUCh as - . . .

,: ,. :
-, ~ ,,, : ' ', , :

2121g~9 `~
- 6 - .Z. 0050/4400 dibutyltin dilaurate, tin(II) octoate or 1,4-diaza-bicyolo[2.2.2]octane, may be present for acc~lerat~ng the reaction of the dii~ocyanate The re~ulting polyurethana, which ie essentially free of isocyanate group~ then di~per~ed in water and the organic ~olvent i~ r~mo~ed to the de~ired extent, in general completely, by di~tillation.
The polyurethane may al~o be prepared by initially preparing a polyuretha~e prepolymer in an organic 301vent. After the addition of the reaction product, the resulting polyurethane prepolymer, which still contain~ isocyanate group~ diRpersed in water.
The reaction with the further component~ can then be carried out. The organic 301vent ca~ the~ be removed, a~
de~cribed above.
The agueou~ dispersio~ co~tains, i~ addition to the polyurethans, at 19a8t one chelate complex co~prising a polyvalent metal a~ ths ce~tral atom and a polydentate ligand.
The amount by weight o~ thi~ co~plex i~ prefer-ably ~rom 0.01 to 10, particularly preferably ~rom 0.01 to 5, very particularly pre~erably ~ro~ 0.02 to 2.5, % by weight, ba~ed on the polyurethane.
The polyvalent metal i~ pre~erably ~alected ~rom the group con~i~ting of the ele~ent~ ~g, Ca, Sr, Ni, Ba, Al, Mn, Fe, Zn, Ti, Cu and Zr.
Mg, Ca, Zn, Al and Zr are particularly pre~erred.
At l~a~t ona ligand o~ the central atom i~ poly-de~tate, ie. ha~ two or mor~ coordinat~ bond~ to the central atom, but pre~erably all ~uch ligand3 are polydentate.
Such coordinate bond~ are usually ~ormed between group~ ~uch a~ primary, ~eoondary or tertiary a~ino group~ or sthylen~ oxide, carboxyl, carboxylate, keto, aldehyde, nitril~ or mercapto group~ or aromatic, ie.
phenolic hydroxyl group~ and the c~ntxal metal atom.
The ~ormatio~ constant K~ ~or the formation of a 121~59 - 7 - O.Z. 0050/44008 complex of a central metal atom ~ and one of the poly-dentate ligand~ L is preferably calculated aa log RF from ~ ~-K, =
~ a~
the values obtained being from 3 to 15 (a = activity, cf.
also Anorganikum, Berlin 1977, 7th Edition, page 497).
Examples of polydentate liyand~ are dinitrilo-tetraacetic acid, pyrocatechol, acetylacetone, 2,2'-bipyridyl, ethylenediamine, diethylenediamine, tri-ethylenediamine and crown ether~.
Preferred chelate ~omplexea are neutral complexes which carry no positi~e or negative charge.
The acetylacetonate~, in particular those of alum1num and of zirconium, are very particularly preferred.
The chelate complexes may be added to the poly-urethane or to the polyurethane dispersion at any time hefore, during or after the preparation of the poly-urethane. The chelate complexa~ are preferably added inthe form of an organic aolution, suitable 501vent8 being, for example, the abovementioned ~ol~ents in the prepara-tion of the polyurethane. Th~ chelate comple~e~ are preferably added to the polyurethane before di~per3ing in water.
The aqueous di~per~ion which i~ u~ed according to the inventio~ a~ an adhesive may furthermore contain an adhe~ion-improving polymer. The ~mount by weight of the~e polymers ~ay be from 5 to 60, pre4erably from 5 to 30, % by weight, based on the polyurethane.
The adhe~ion-impro~ing polymer i8 likewiae added to the polyurethane or to i~s prepolymer in water pref~r-ably befor~ di~persing. In the ca~e of the prepolymer~, the further reaction to give the polyurethane i~ then carried out.
Suitable adhe~ion-improving poly~ers are a large nu~ber of different polyconden~ate~, freo radical poly-mera or polyadduct~.

21219~9 - 8 - O.Z. 0050/44008 The adhesion-impro~ing polymQrs are preferably phenol/formaldehyde conden~ation re~in~ or similar reaction products (in particular phenol resin3) of a compound (I), ~elected from the group consisting of aromatic compound~ having one aromatic ring, two fu~ed aromatic rings or two aromatic ring~ which are bonded by a Cl-C9-alkylene and are sub~tituted on at lea~t one ring by at least one hydroxyl group and are unsub~tituted or - substituted on the aromatic ringa by from 1 to 3 Cl-Cl2-alkyl or Cl-Cl2-alkoxy group~, and the mixture~ of the~e aromatic compounds with a compound (II) ~elected ~rom the group con3i~ting o~ compounds having 1 to 20 carbon atom~
and at lea~t one keto or aldehyde group, a C4-Cl8~
diolefin, co~pounds having 2 to 10 carbon atom~ and at lea~t one triple bo~d and mixture~ thereo~ :
Preferred co~pound~ (I) are ~- or ~-naphthol, bisphe~ol A or phenol which i~ un~ubstituted or 8ub-3tituted by ~rom 1 to 3 Cl-C8-alkyl or alkoxy groups. The 3ub~titue~t~ are preferably mata or para to the hydroxyl group on the aromatic ring~. Un ub~tituted phenol, a-and g-naphthol and bisphenol A are particularly prefer~ed.
Preferred compounds (I) ar0 co~pound~ which hav~
one or two hydroxyl group~, parti~ularly preferably one hydroxyl group.
Compounds (II) are pr~ferably compounda ha~ing 1 to 14 carbon ato~s and ono or two keto or aldehyde group~, preferably one keto or aldehyde group. The~o compound~ may be aliphatic or aromatic or ~ay contain both aliphati~ and aromatic group3. In addition to thz keto or aldehyde group, the compound~ preferably contain no ~urther ~unotional groups, ie. no ~urther heteroatom~
apart from the oxygen atom o~ the aldehyde or keto group.
~xamplo~ of compound~ (II) are $ormaldehyde, acetald~hyde, n-propionaldehyde, glycolaldehyde, i~o-propionaldehyda, n-butyraldehyde, isobutyrald~hyde, benz-aldehyde, glyoxal, glutardialdehyde, oxaglutardialdehyde, , ' ' ' ~ ' : ' ' , ' ' . '; ' ~ . ' 21219~9 - 9 - O.Z. 0050/44008 acetone, methyl ethyl ketone, benzophenone, butadie~e, cyclopentadiene and bicyclopentadiene, acetylene, acrolein, methylacrolain or mixtures thereof.
Formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, i~obutyraldehyda, acetone and mixtures thereof are particularly preferred.
Reaction products of the compounds (I) and (II) are generally known. The reaction take~ place similarly to the phenol/formaldehyde condensation, by addition of the keto or aldehyde group or o the double or triple bond predominantly ortho or para to ths hydroxyl group on the aromatic ring.
The molar ratio of the compound (I) to (II) in the condensation reactio~ is pre~erably from 1 : 0.1 to 1 : 2, particularly preferably $rom 1 : 0.7 to 1 : 1.
The reaction i8 carried out in general by ini~
tially taking the compound (I) with an acid a~ a catal~
yst, for example a hydrohalic acid, boron trifluoride, sulfuric acid, p-toluene~ulfonic aaid or dodecylbenzene-sulfonic acid, and the~ meterin~ in the compound (II) at O to 250C, pre~erably from 20 to 230C.
After the end of the ~etering, postco~densation can be carried out, in particular at fro~ 20 to 250C, preferably from 80 to 200C. During the reaction, water can, if desired, be r~moYed from the reaction mixture, if necessary with the use of an entraining age~t.
The cour~e of tha reaction can be monitored by mea~uring the ~oftening point of the re~ulting reaction product.
~he reaction prod~ct~ preferably ha~e a ~oftening point (determined according to DIN 52,011) o~ from 50 to 200C, particularly preferably rom 80 to 140C, very particularly prefexably rom 120 to 140C.
Epoxy resins, preferably reaction producta of epoxide3, ~uch a~ epichlorohydrin, with bi~phenol A, are also auitable; tho~e ha~ing weight average molecular weight~ (-M~) of ro~ 500 to 5,000 and ~oftening poin~s 21219~)9 - 10 - O.Z. 0050/44008 of from 80 to 130C are preferred.
Other suitable adhesion-improving polymer~ are polyvinyl acetate, polyvinyl chloride, polymethacrylates, styrene/acrylonitrile copolymer~, polyamide~, polyethers, polye~terR, polyetherdiol~, polye~terdiols, poly-urethanes, in particular polyur~thane~ free of salt group~, and phenacrylate.
Praferred polyvinyl acetates are the homopolymer~
of vinyl acetate. Ita copolymer~ which contain up to 10%
by weight of comonomer~ ~uch a~ vinyl laurate, vinyl ~tearate or, preferably, (meth)acrylic acids, fumarates or maleate~ of Cl-C8~alkanols, such aE methanol, n-butanol or 2-ethylhexanol, may al80 be used. The polymers u~ually have a R value, mea~ured at 25C in cyclohexanone according to DIN 53,726, of from 45 to 60. Polyvinyl chloride i~ understood in general a~ meaning the homo-pol~mers of vinyl chloride and its copolymers which contain up to 10% by weight of comonomer~, such as ethyl0ne or vinyl acetate. Their R value (25C, cyclo-hexanone, DIN 53,726~ should be from 45 to 55. The polymethacrylate~ used by the skilled worker are usually homopolymers of methyl acrylata or it~ copolymers with up to 10% by weight, ba~ed on the copolymer, of vinyl acetats, acrylates of Cl-C8-alkanol~ or methacrylatea of C2-C3-alkanol~. Their melt flow index MFI, determined according to DIN 53,735 (230C/3.B kg), i~ in general from 0.1 to 3Ø The~e polymero ara prepared in general by free radical ma~, solution or ~mulaion polymerization of the ethylenically unsaturated monomer3 at from 30 to 150C with sub~equent drying. Such polymers are generally known, or example from ~o~ben-Weyl, Methoden der organischen Chemle, Volume E20, l9B7, page~ 1115-1125, 1041-1052 and 1141-1174.
guitable polyamide~ have a R value o~ from 65 to 80, mea~ured in H2SO~ at 25C according to DIN 53,727.
These ars u~ually pol~mers which are derived from lactams having 7 to 13 ring membQrs, ~uch as ~-caprolactam, "

,;:: . .: .: - . . .

21219~9 - 11 - O.Z. 0050/~4008 e-capryllactam or ~-laurolactam, for example polycapro-lactam (PA6), and polyamide~ which are obtained by reacting dicarboxylic acid~ with diamines. Examples of -- -the~e are polyhexamethyleneadipamide (PA66), polyhexa-methylene0ebacamide (P~610) andpolyhexamethylenedodecan-amide (PA612). Examples of suitable dicarboxylic acids are alkanedicarboxylic acids of 4 to 12, in particular 6 to 10, carbon atom3 and phthalic acid, terephthalic acid and isophthalic acid, a~ well a~ any mixture~ of the~e acids. Examples of diamines are alkan~diamine~ of 4 to 12, in particular 4 to 8, carbon atom~ and m-xylylene-diamine, p-xylylenediamine, hydrogenated derivative~
thereof, bi~(4-aminophenyl)methane, bi~(4-aminocyclo-hexyl)m0thane or 2,2-bi~(4-aminophenyl)propane or mix-ture~ thereof. Owing to thoir good ~olubility, copoly-mer~ are preferred, for example a copolya~ide of from 30 to 40% by weight of adipia acid, from 15 to 20% by weight of hexamethyle~ediamin~ and from 30 to 35% by weight of ~-caprolactam or from 15 to 20% by weight or ~-amino-caproic acid. The preparation of these know~ polymer~ i3 general technical knowledge, cf. for example Rompp, Chemielexikon, 8th Edition, page~ 2861, 3058 and 3267, or EP-A-129 195 and EP-A-129 1960 The polyetherdiols are known per 8e, for example from Runst~toff-Handbuch 7 (1983), 42-54. Examplea are polyethylene oxide, polypropylene oxide or polytetra-hydrofuran or their copoly~er0 ha~ing two terminal hydroxyl ~roups. They are prepared in a known manner by, in general, anionic polyaddition, cf. for example N.~.
Gaylord, High Polymers, Vol. 13, New York 1963, Par~ I.
Polyetherol~, which are grated w~th ethylene oxide to incr~ase the raactivity, are o~ minor importance. The polyetherdioln generally have a ~olocular weight of from 300 to 3,000, corre~ponding to a K value of from 25 to 60 in D~F at 25C according to DIN 53,726. Preferred molecular weight~ are from 800 ~o 2,200.
The polyether uaed is, for example, polyethylene ' ' '~ ": ~;

2~2~9~9 .~. , - 12 - O.Z. 0050/44008 oxide, polypropylene oxide or polytetrahydrofuran. The polyether3 u~ually havs a R valu~ o_ 4rom 20 to 50 in DMF
at 25C according to DIN 53,726. They are generally known, for example from Encyclopedia of Polymer Scien~e 5 and Technology, Volume 6, 1967, page 103 et seq., Voluma 9, 1968, page 668 et seq., and Volume 13, 1970, pag~ 670 et ~eq.
Preferred polyestera are monomer-free un~aturated polyester resin~. These are known condensate~ of poly-ba~ic, in particular dibasic, carboxylic acids or the e~terifiable derivati~ thereof, in particular the anhydride~ thereof which are esterified with polyhydric, in particular dihydric, alcohols and may contain addi-tional radical3 of monoba~ic carboxylic acid~ or mono-hydric alcohol~. Examples o~ starting materials are maleic acid, fumaric acid, phthalic acid, i~ophthalic acid, terephthalic acid, malzic anhydride, phthalic anhydride, isophthalic anhydride, ethylene glycol, propylen~ glycol, 1,4-butanediol and neopentylglycol.
Re~in3 whi~h are prepared by condensing bisphenol A, epichlorohydrin/bi~phenol A conden~at~ and mathacrylic acid are of minor importanca ~or the purpose~ of the pre~ent invention. In this context~ monomer-~ree mean~
the UP re~ins arc insoluble in the monomers ~uitable for crosslinking, such a~ ~tyrene. The products usually have a ~isco~ity of from 1,000 to 6,000, in particular from 2,000 to 4,000, m~a.a at 150C.
Suitable polyesterdiols are conden~ate~ which have two terminal OH groups and are obtained 4 rom dicarboxylic acid3, such aa adipic acid or isophthalic acid, and diol~, for example 1,4-butanediol, 1,6-hexane-diol or neopentylglycol.
The molecular weight range of the polye~terdiol~
which can be used i~ in general fro~ 300 to 5,000, preferably from 800 to 2j500, corre~ponding to a ~ ~alue o~ from 30 to 55 in DMF at 25~C according to DIN 53,276.
The~e polymor~ and their preparation are generally known ,.

`` 212~9~9 . ` .
- 13 - O.Z. 0050/44008 from Kunststoff-~andbuch 7 (1983), 54-62, and DE 12 68 842.
PolyursthaneE which are free of alt groups are known addition polymer~ based on polyetherdiols or polye~terdiols, isocyanates, ~uch a3 hexamethylene diisocyanate, or 2,4-dii~ocyanatodiphenylmethane, and po~sibly bi- or trifunctional chain extenders which are prepared by conventional proce~se~ (Runststo~f-~andbuch, Karl-Hanser-Verlag, Volume 7 (1966)). Low molecular weight condensates (K value of from 25 to 60 in DMF at 25C according to DIN 53,726) are preferably u~ed.
Cros~linked polyurethane~ are of minor importance.
Phenacrylate~ are preferably prepared by subject-ing bt~phenol A glycidyl ethera esterified with acrylic acid or methacrylic acid to an addition reaction with terephthalic acid. Phenacrylate~ based on epoxidized novolako may alao be u3ed. The R value~ of the polymer~
are in general from 30 to 55 (in cyclohexane at 25C
according to DIN 53,726).
The aqueouR di~per~ion~ which, according to the invention, are u~ed as adhe~ive~ and which contain a chelate complex and may contain an adhesion-improving polymer pref~rably have a solid~ content of from 10 to 70, in particular from 20 to 50, ~ by weight.
They can be used, for example, directly a~
contact adhe~ive~ for bonding a very wide range of substrate~, ~or example wood, plastic, gla R and metal.
In order to obtain special propertie~, further additives, such as pla~ticizers, ~ilm-~orming a~ tant~, fillers or polyacrylate~, polyvinyl acetate~, 3tyrens/butadiene copolymers a~ component~ of the mixturet etc., may be added to the di~persion~. Advantageou~ly, adhe ive coatings are applied to the ~ur~aces o~ both ~ub~trate~
to be bonded. ~ ~ -The ~queou~ disper~ions give adhesive bond~
having high strength, in particular high heat di~tortion resi~tance.

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.

`` 2~2~9 .,~
- 14 - O.Z. 0050/44008 EXAMP~ES
The abbreviations u~ed in the Example~ below have the meaning~ given below:
AD~ = Adipic acid sl4 = 1,4-~utanediol TDI = Toluylene diisocyanata D I = Hexamethylene dii~ocyanate IPDI = I30phorone diisocyanate PUD = Sodium salt of the Michael adduct of acrylic acid and ethylenediamina DBTL = Dibutyltin dilaurate DMPA - Dimethylolpropionic acid TMP = Trimethylolpropana ' '' ' - ' ~'' :. . : ~ : . .. , : : ' . . :
,: ' '' ', ~ , ' ' ' :' ' : .

` 21219~9 , ~ .
.
- 15 - O.Z. 0050/44008 EXAMPLE lA tComparative Example) _ Molar amount Part~ by weight ~mmol~ ~g]
_ Polye~terdiol (OH number: 198 492 TDI 147 25.6 HDI 178 24.7 DBTL 0.1 Acetone I 133 .
Aceton~ II 532 PUD ~alt (40% ~trength) 94 42.0 Phenol/~ormaldehyde conde~3ate resin, ~oftening point (DIN 52,011) 128C 240 Ac~tone III - ¦ 240 Demineralized water l l 1200 The TDI wa~ added to the ~ixture o4 dewatered polye~terdiol, prepared ~rom adipic acid and 1,4-butane-diol, acetone I and cataly~t. A~ter a reaction time of one hour at 65C the HDI wa2 added and the reaction was continued for a ~urther 90 minute~. After acetone II had been added, the reaction mixture had an NCO content of 0.75%. At 50C, chain extension wa~ e~focted with P~D
salt, which wa~ present in the 4Orm o~ a 40% ~trength ~olution i~ water. A~ter 5 minute~, th~ re~in ~olution, prepared from acetone III and a conden~ate o~ phenol and formaldehyde, was added and ~tirring was carried out for 5 minutes at 50C. Thereaftar, di~paroing wa effected with water and the acetone wa~ distilled o~. The di~persion waa brought to a ~olid~ aontent of 40~ by redilution with d~mineralized water.
EX~MPLES lB AND lC
The disper3ion wa~ prepared ~imilarly to Example .' ' ' I ' ,' .

21219~9 - 16 - O.Z. ~050/~4008 lA (Comparative Example), except that, after the addition of the re~in, 8.0 g o~ aluminum (or zirconium) acetyl-acetonate, dia~olved in 100 ml of acetone, were added.
EXAMPLE 2A (Comparati~e Exa~ple) Molar amount Part~ by weight ~mmol] ~g]
Polye~terdiol (OH number: 191 476 45.O
1,4-3utanediol 176 14.1 Trimethylolpropane 17.4 2.3 IPDI 436 96.9 DBTL 0.2 Acetone I 133 _ . ...
Acetone II 532 PUD salt (40~ ~tre~gth) I 94 35.0 Phenol/formaldehyde condansate re~i~, 80 tening point (DIN 52,011) 128C 240 Acetone III ~ ¦ 240 Demineralized watsr 1 1200 The IPDI wa~ added to the mixture of dewatered polyest2rol, prepared from adipic acid a~d 1,4-butane-diol, 1,4-buta~adiol, trimethylolpropa~e, acetone I and catalyet and the reaction waa carried out for 130 minutea. Ater acetone II had been added, the reaction mixture had an NCO content of 0.57%.
At 50C, chain exten~ion wa~ carried out with PUD
aalt, which wa3 preaent in the for~ of a 40~ ~trength ~olution in water. After 5 mi~utec, the reain solution, prepared from acetone III and a conde~ate of phenol and formaldehyde, waa added and ~tirring wa~ carried out for 5 ~inute~ at 50C. Thereafter~ disperaing was effected with water a~d the acetone was diatilled off. The . ":., ,: : ~ ::.: ~

-` 21121 ~9 o.z. 0050/44008 disper~ion was then brought to a 301ids content of 40% by redilution with d~ineralized water.
EX~MPLES 2B AND 2C
The disper~ion was prepared ~imilarly to ~xample 2A (Comparative Example), except that, after the addition of the resin, 8.0 g of aluminum (or zi~conium) acetyl-acetonate, di~olved in 100 ml of acetone, were added.
EXAMPLE 3A (Comparative Example) _Molar amount Parts by weight ~mmol~ ~g]
Polypropylene oxide 298 597 (OH number: 56) I .
Dimethylolpropionic acid 160 21.5 DBTL 0.3 :: :
Acetone 978 :^ :
_ _ :
Demineralized water 1200 30% strength by weight 112 4.5 NaOH solution . . ' ,~
The TDI wa~ added to the mixture of dewatered polypropylene oxide, dimethylolpropionic acid and catalyat and the reaction was carried out at a reaction ~ :~
temperature of 105C for 3 hours. After acetone had been added, the reaction mixture had an NCO content of O . 45% .
The ~olution was cooled to 30C, after which the NaOH solution wa~ added and dispersing wa~ effected with water in ths course of 20 minute~ and tha acetone was di~tilled off. The dispersion wa3 then brought to a aolid~ content of 40% by redilution w~th demineralized water.
EXAMP~ES 3s AND 3C
The disper~ion wa~ prepared 0i~ilarly ~o Example 3A (Comparativo Example), except that, after the addition of NaO~, 8.0 y of aluminum (or zirconium~ acetyl-acstonate, di~sol~ed in 100 ml of acetone, were added.

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` 2~219~9 ,,, ~
- 18 - O.Z. 0050/44008 EXAMPLE 4A (Comparative Example) The disper ion was prepared ~imilarly to Compara-tive Example 1. Instead of the phenol/formaldehyde resin, howe~er, a resin based on phenol and a mixture o~
n-butyraldehyde and i~obutyraldehyde wa~ u~ed (molar ratio of n-butyraldehyde to isobutyraldehyda = 1 : 1).
The aoftening point (DIN 52,011) wa~ 153C.

The dispersion wa~ prepared ci~ilarly to Example 4A (Comparative Example), except that, after the addition of the resin, 8.0 g of aluminum (or zirconium) acetyl-acetonate, di ~olved in 100 ml o~ acetone, were added.
~, EXAMPL~ 5A (Com~arative Example) ~
_ . .
Molar amount Parts by weight .
. ~mmoll [g] . ~;
_ _ Polye~terdiol (OH number: 196 489 TDI 159 27.8 _ 159 26.8 DBTL 0.1 Acetone I 133 . .

Ac~tone II ~ l l 532 _ PUD salt (40~ ~trength) 94 42.0 Ph~nol/ i30butyraldehyde condensate resin, ~o~teni~g poi~t (DIN 52,011) 132C 240 _ I .
Acetone III ¦ 240 Deminéralized water ¦ 1200 The prsparation was carried out .imilarly to Example 1, except that the r~action ti~e with XDI wa~
i~crea~ed to ~0 minute3.

.
.
.: . .- . : :

`j 212~9~9 - 19 - O.Z. 0050/44008 EXAMPLES 5~ AND 5C
The di persion wa~ prepared similarly to Example 5A (Comparative Example), exc~pt that, a~ter the addition o$ the resin, 8.0 g of aluminum (or zirconium) acetyl-acetonate, di~solved in 100 ml of acetone, wera added.

EXAMPL~ 6A (Comparative Example) Molar amount Parts by weight [mmolj _ Polyetherol (OH number: 200 401 56) Dimethylolpropionic acid 161 21.6 DBTL _ _ 0.1 _ I _ --~
Acetone I _ 1 ¦ 684 Phenol/i~obutyraldehyde condensate r~sin, softening : ~
point (DIN 52,011) 128C 240 : ::
_ ~: :
Acetone II _ 240 Demineralized wat~r 1200 __ .
30% ~trength by weight 112 4.5 NaOH solution The TDI wa~ added to the mixture of dewatersd polyetherol (polypropylene oxide having an OH ~unctional-ity of 1.93 equi~alent/mole), dimethylolpropionic acid and cataly~t, and the reaction wao carried out ~t reaction temiperature o~ 105C ~or 3 hours. Aft~r acetone I had been added, the reaction mixtura had an NCO content o~ 0.56~.
A~t~r neutralization with the NaO~ 301ution, the resin solution, pr~pared from acetone II and a conden~ate of phonol and a mixture o~ n-butyxaldehyde and i80-butyraldehyde (molar ratio 1 : 1), wa~ added. The solution wa~ cooled to 30C, after whi~h disper~ing wa~

: : :: ~: I

, :: -: : . :: :
: :.. ::. . ,:, , : : : -, 2~2~59 - 20 - O.Z. 0050/44008 effected with water in the cour~e o~ ~0 minutes and the acetone wa~ di~tilled of~. The dispersion wa~ then : -brought to a solid~ content of 40% by redilutio~ wtih demineralized water. ~ .--EXAMPLES 6~ AND 6C
The disper~ion wa~ prepared ~imilarly to Example 6A (Comparative Example), except that, after the addition of the resin, 8.0 g of aluminum (or zirconium) acetyl-acetonate, dis~olved in 100 ml o~ acetone, were added. ~ :
Contact adhasive bonding at room temperature Sample preparation:
The disper~ion~ were thickened with 5% by weight, ba~ed on it~ ~olid, of pyroge~ic ailica.
Shear ~trength~
The particular di~persion~ were applied to beech wood panel~ over an area of 150 x 50 mm2 with a knifa : :~
coater having 1 mm teeth and were dried ~or 60 mi~ute~ at room te~erature. The~e te~t ~pecimen5 were then immediately adhe~ively bonded by pre~ing them for 30 ;~
~econds at room temperature under a pressure of O.5 N/m~2 . The ~hear ~trength wa~ mea~ured immediately (inatantaneou~ ~trength) and after 3torage ~or 7 day~ at `~
room temperature (final ~tre~gth), in N/~ma. :~
Heat di~tortion re~istance:
A har~board wa~ adhe~ively bonded with a PVC ~ilm over an area o~ 200 x 200 mm3 (contact adhe~ive bonding at room temperature). ~he PVC film was ~ubjected to a load of 300 g at a peeli~g angle of 180. The temperature wa~ increased by 10C e~ery 30 minutes. The max$mum temperaturo at which the PVC film i3 ~till not completely detached ~rom the hardboard i~ ~tatsd.

.. . . . .- .... - . . . . .................... ~ .

-: ... ,,, " . ~; , . . i ~ . -` 2~219~9 - 21 - O.Z. 0050/44008 EXAMP~S 6B AND ~C
The di~per~ion waa prepared ~imilarly ~o Example 6A (Comparative Example), except that, after the additlon o~ the resin, 8.0 g of aluminum (or zirconium) acetyl-acetonate, dis~olved in 100 ~1 of acetone, were added.
Contact adheaive bondins at room temperature Sample preparation:
The dispersions were thickened with 5% by weight, - based on it~ solid, of pyrogenic silica.
Shear strength:
The particular dispersions were applied to baech wood panal~ ov~r an area of 150 x 50 mml with a knife coater having 1 mm teeth and were dried for 60 minutes at room temperature. These t98t specimens were then immediately adhesively bonded by preR~ing them for 30 seconds at room t~mperature undor a pressure of 0.5 N/mm2. The shear strength wa~ mea~ured immedia~ely (instanta~eous ~trength) and after storage for 7 day~ at room temperature (final ~trength), i~ N/mm2.
~eat di~tortion resi~tance~
A hardboard was adhe~i~ely bondad wit~ a PVC film over an area o_ 200 x 200 ~m~ (co~tact adhesive bonding at room temperature~. The PVC 4ilm wa~ ~ubjected to a load of 300 g at a peeling angle of 180. The tamperature wa~ increased by 10C every 30 minute~. The maximum temperature at which the PVC film i ~till not completely detached ~rom the hardboard i8 ~tated.

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` 2~21~9 ~` - 23 - O.Z. 0050/44008 Te~ting of the contact adheaive bond af ter flash activa-tion (heat actiYation) Sample preparation:
The diaper~on~ were thickened with 2% by weight, based on their solid, of polyvinylpyrrolidone.
Peel strength:
The di~persion3 were applied with a brush (1 inch, ~ine bristles) uniformly to styrene/butadiene rubber (SBR1 rubber having a Shore A hardne3s of 90 (cf.
lC DIN 16,909)) over an area of 30 x 130 mm2 and were dried for 45 minute~ at room t~mperature. After the adhe~ive ~ilms had been heated once by IR radiation to 80C in the cour~ o$ about 5 ~econds (flash activation), the samples were pre3eed for 10 second~ at 0.5 N/mm2. The peel strength was measured immediately (in~tantaneous strength) and after storage for 5 day~ in a conditioned chamber (23C/50% relativ0 humidity3 (final ~trength), according to DIN 52,273.
Heat distortion re~i~tance:
The te~t ~pecimen~ were produced a3 for testing of the peel strength. After being heated for 1 hour at 50C, they were loaded, at 50C, with 5, 10, 15, 20, 25 and 30 N in a~canding order, for 10 minute~ in each ca3e.
If the adhQsive bond held, the load waQ r~moved from the sample and tha sample wae heated to 60C for 30 minute~
and te~ted again up to 30 N in 10 minute step~. After each cycle, the test temperaturs wa3 i~crea~ed by 10C.
The temperature (C) and the load (N) at which breaki~g of the adhesive bond by more than 50 mm wae det~ctable are stated in each ca~e.

21219~9 24 - O.Z. 0050/44008 _ _ .
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Claims (7)

1. Process of an aqueous dispersion, containing a polyurethane which is essentially composed of a) organic polyisocyanates, b) polyhydroxy compounds having a molecular weight of from above 500 to 5,000 g/mol, c) compounds having at least one group reactive toward isoctanate and having at least one ionic group or group convertible into an ionic group and d) if required, compounds which differ from (c) and have at least two functional groups reactive toward isocyanate and a molecular weight of from 60 to 500 g/mol, and at least one chelate complex comprising a polyvalent metal as the central atom and a polydentate ligand, as an adhesive.

2. use as claimed in claim 1, wherein the content of the chelate complex in the dispersion is from 0.01 to 5%
by weight, based on the polyurethane.

3. An aqueous dispersion, containing a polyurethane and a chelate complex as claimed in claim 1, wherein the polydentate ligand is an acetylacetonate.

4. An aqueous dispersion, containing a polyurethane and a chelate complex as claimed in claim 1 and in addition an adhesion-improving polymer.

5. An aqueous dispersion as claimed in claim 4, wherein the adhesion-improving polymer is a phenol resin.

6. An aqueous dispersion as claimed in claim 4.
wherein the adhesion-improving polymer is added to the polyurethane or to a polyurethane prepolymer prior to dispersing in water and, in the case of the polyurethane prepolymer, the further reaction to the polyurethane is carried out after dispersing.

7. An adhesive bond obtainable by using an aqueous dispersion as claimed in claim 1.