HK1070380B - Water-resistant adhesives, their preparation and use - Google Patents

Description

Waterproof adhesive, preparation method and application thereof

The invention relates to aqueous dispersion adhesives based on polymer dispersions and having high wet bond strength, to a process for preparing them and to their use for bonding wood and other substrates, in particular porous or semi-porous substrates.

Polymer dispersions, particularly those based on polyvinyl esters (e.g., polyvinyl acetate), are widely used as white glues in industry for bonding wood and other porous or semi-porous substrates. If such cements are likely to encounter water after application, they can also be made into water-repellent articles by using specific crosslinkable or self-crosslinking comonomers during their preparation by emulsion polymerization and/or by subsequently adding specific crosslinker additives (usually in the form of crosslinker resins) and crosslinking catalysts. This mode of action consists in the incorporation of hydrophilic protective colloids (e.g. polyvinyl alcohol), which are generally used for colloidal stabilization.

This makes it possible to obtain specific articles which meet the requirements of the relevant standard (for example DIN EN 204).

Cold water resistant adhesives, such as those used in kitchen furniture components, are required to achieve at least D3 level durability (wet bond strength ≥ 2N/mm after 4 days storage with cold water following D3/3 test procedure²). For outdoor applications or in window construction (for example in the manufacture of window frames), those having D4-grade durability (wet bond strength. gtoreq.4N/mm after storage in boiling water for 6 hours and in cold water for 2 hours after D4/5 test procedure)²) The anti-boiling water binder of (1).

Also in do-it-yourself (DIY) applications, such as in bonding wood flooring, nowadays are routinely used water-repellent wood adhesives based on dispersions, especially those which have been generally based on D3 quality grades. Due to the period of sale, which in some cases is greatly prolonged by the holding time at the builder and end user, it is required that the product has a long shelf life, during which the dispersion must not have any loss of quality and its increase in viscosity must not be too great. The quality requirements of the consumer also include not only compliance with the relevant test standards (for example EN 204/D3) but also a significant excess of these standards, preferably of more than 50% to more than 3N/mm²。

Another requirement, especially in the central and northern european regions, relates to a low VOC content (VOC ═ volatile organic compounds). A low formaldehyde content is required here, formaldehyde being incorporated into the dispersion as a self-crosslinking comonomer or in particular as an external crosslinker resin, as described, for example, in DE-B-2261402.

Another aspect is the price drop of the base adhesive (i.e., the dispersion provided to the adhesive industry by the manufacturer of the adhesive base material for end-use processing), which has been on the market for many years. This trend is forcing producers of these intermediates to enhance cost reduction by reducing the number or cost of starting materials and/or by more reliable manufacturing processes.

Polymer dispersions based on polyvinyl esters, in particular polyvinyl acetate, are large articles which can be prepared by aqueous emulsion polymerization of vinyl acetate in the presence of polymeric stabilizers (protective colloids). A review of the preparation and use of polyvinyl acetate dispersions can be found in many references, for example in Handbook of Adhesives (i.skeist, third edition, chapter 21). It is also described how, for example, the comonomer N-methylolacrylamide is widely used for the preparation of self-crosslinking vinyl acetate polymers. This monomer is currently relied upon in low cost articles of D3 grade cold water resistant adhesives because of its favorable price, ready availability and effectiveness.

As expected, relatively much patent literature is available in the field of adhesives on self-crosslinking polymer dispersions, in particular polyvinyl ester dispersions containing methylol monomers, such as N-methylol (meth) acrylamide.

The documents DE-C2620738, DE-A-3942628, EP-B-826,008 and EP-A-1,170,311 cited here by way of example relate to adhesive systems which are crosslinked by acid catalysis and are based on copolymers of vinyl esters with crosslinkable comonomers, including N-methylolacrylamide. According to the disclosure of the examples, these binders in combination with strong water-soluble acids or their metal salts, in particular Cr (III), Al (III), Fe (III) and Zr (IV) salts, can give a standard bond strength > 2N/mm²EN 204/D3 (or DIN 68602/B3 before) grade bonding effect.

Due to the sensitivity of these crosslinkable monomers to industrial processing, their industrial application often hides serious problems: such as premature homopolymerization in aqueous solutions to be sold. The temperature range must be carefully selected during emulsion polymerization to avoid thermally induced premature crosslinking. There is also a large fluctuation in the viscosity of these end products. Moreover, when used in relatively large amounts, the storage stability of the final product formulated with acid is drastically reduced. In addition, the N-methylol monomer also introduces a certain amount of free formaldehyde into the dispersion, which remains as a process impurity.

There is no suggestion in the documents cited above to replace these comonomers completely or at least partially with other systems.

Also known are warp yarns C₁-C₆The alkanol-etherified and therefore less sensitive N-methylol monomer derivative replaces the N-methylol monomer; due to their low reactivity, the desired effect cannot be achieved with these N-alkoxymethyl (meth) acrylamides. Furthermore, the higher price of these articles results in the adhesives being significantly more expensive.

As mentioned above, it is also known to subsequently add to the dispersion various additives and external crosslinker resins which can impart water-resistance to the bonds produced by these adhesives or further enhance such water-resistance. Of course these additional materials may also be used in combination with the N-methylol monomer containing preparations described above.

Widely used on the market as reactive additives or as components of dispersions are blocked polyisocyanates, as described in EP-A-206,059, or blocked polyfunctional aldehydes, as described in EP-B-686,682, both of which allow extremely high adhesive strengths with boiling water resistance up to D4. Such binders therefore contain little or no formaldehyde and no additional formaldehyde is added to the product; however, due to the high reactivity, the shelf life that can be achieved with this adhesive is short, making the article unsuitable for use as a one-component system in DIY applications.

It is also prior art to improve the wet bond strength of emulsion polymers already containing methylol monomers by adding a resin. By way of example, mention may be made of EP-B-623,661, in which it is proposed to add to the dispersion a formaldehyde resin selected from: resorcinol-formaldehyde resins, urea-formaldehyde resins, melamine-formaldehyde resins and phenol-formaldehyde resins. These systems can optionally have the following disadvantages: high reactivity (which does not allow for extended shelf life), introduction of free formaldehyde, or for special products from the above where formaldehyde is reduced, the problem of residual formaldehyde concentration continues to exist but at the same time reduced reactivity and higher price.

Another class of resins useful as additives in polyvinyl acetate based dispersions consists of special N-methylol reactive resins, which may be used alone or in combination with other resins. GB-A-1,204,818 lists polyalkoxyalkyl-and polyalkanol diazines, -triazines and-tetrazines, imidazolinones and thioimidazolinones. Specific examples cited in this document are tetrabutoxymethylphenylguanamine and 1, 3-dimethylol-4, 5-dihydroxy-2-imidazolidinone. The last-mentioned compounds are also known as dimethylol dihydroxyethylene urea (DMDHEU) and can be used as textile finishing agents. There is no mention of its use in dispersions containing free radical comonomers having N-methylol groups.

WO-A-01/49788 (corresponding to EP-A-1,246,868) lists the same or structurally related crosslinker resin types as the above-mentioned resin types and these crosslinker resin types include methylol-substituted imidazolinones, such as 1, 3-dimethylol-4, 5-dihydroxyimidazolidinone (4, 5-dihydroxy-N, N' -dimethylolethyleneureA), methylol-substituted pyrimidinones or methylol-substituted triazinones or their self-condensation products or mixed condensates of two or more of said compounds, or mixtures of two or more of said compounds. In a preferred embodiment, the polymer dispersion comprises a crosslinker resin based on 1, 3-dimethyloldihydroxyimidazolidinone (4, 5-dihydroxy-N, N' -dimethyloldihylene urea), optionally in the form of the compound itself, a self-condensation product thereof or a mixture thereof. The disadvantage here is again that these compounds contain considerable amounts of intrinsic formaldehyde, up to 1.1% by weight. In addition, these compounds have no fundamental advantages and are also highly reactive compared to the use of copolymerizable methylol monomers to make D3 adhesives.

None of the above publications mention a process which can be used to achieve the desired reduction in the N-methylol content of the waterproofing adhesive formulation without at the same time impairing the wet bond strength properties which are highly appreciated by the consumer, in particular in accordance with DIN EN 204/D3.

It is therefore an object of the present invention to provide a water-repellent adhesive which achieves at least the same or improved wet adhesion strength, preferably a wet adhesion strength of DIN EN 204/D3-grade durability, and at the same time has a reduced content of copolymerizable N-methylol groups compared with conventional adhesives comprising polymer dispersions of binding polymers containing N-methylol groups.

This object is achieved by the dispersion adhesives described below.

The invention provides an aqueous dispersion adhesive based on a polymer dispersion, preferably having a pH of 2 to 6, comprising at least one emulsion polymer containing crosslinkable N-methylol groups, at least one protective colloid, and at least one crosslinker containing N-methylol groups which are completely or partially etherified with one or more alkanols and/or further hydroxyl groups which are completely or partially etherified with one or more alkanols, and wherein the N-methylol groups are obtained by adding up to 2.0% by weight, preferably 0.01 to 1.5% by weight, in particular 0.05 to 0.8% by weight, based on the total amount of monomers, of a comonomer containing N-methylol groups to the emulsion polymer, the crosslinker being selected from the group consisting of: hydroxymethylated ethylene urea, hydroxymethylated propylene urea, hydroxymethylated dicyclo-glyoxal diurea (bicyclyglyoxaldiurea), hydroxymethylated dicyclo-malondialdehyde diurea (bicyclymalonaldehyde diurea), or combinations thereof.

One class of emulsion polymers which are the basis of the dispersion binders according to the invention consists of copolymers prepared by free-radical emulsion polymerization and which are composed predominantly based on vinyl esters as main monomers and comprise at least a comonomer containing a crosslinkable N-methylol group.

Suitable primary vinyl ester monomers preferably include vinyl formate, vinyl acetate, vinyl propionate, vinyl isobutyrate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl esters of saturated branched monocarboxylic acids having 9 to 11 carbon atoms in the acid residue, vinyl esters of relatively long chain saturated or unsaturated fatty acids (e.g., vinyl laurate or vinyl stearate), vinyl esters of benzoic acid, and vinyl esters of substituted derivatives of benzoic acid (e.g., vinyl p-tert-butylbenzoate). Of these monomers, however, vinyl acetate is particularly preferred.

The vinyl esters can be used individually for the polyvinyl esters or can be present in the copolymer alongside one another in the form of a mixture. The vinyl esters from the stated type are generally at least 50% by weight, preferably at least 75% by weight, as part of the total amount of monomers in the copolymer.

The emulsion polymers used according to the invention contain crosslinkable N-methylol groups, which are introduced by copolymerization with comonomers containing N-methylol groups. Preferred examples of such comonomers are N-methylolacrylamide, N-methylolmethacrylamide, allyl N-methylolcarbamate, N-methylolmaleimide, N-methylolmaleamic acid, and N-methylolamides of aromatic vinyl carboxylic acids (e.g., N-methylol-p-vinylbenzamide). When the aqueous dispersion adhesive of the present invention is used as a waterproofing adhesive, N-methylolamides of acrylic acid and methacrylic acid are particularly preferred. The proportion of these comonomers relative to the total amount of monomers is up to 2.0% by weight, preferably from 0.01 to 1.5% by weight, in particular from 0.05 to 1% by weight.

In addition to the N-methylol group-containing monomers described above, further comonomers which are particularly suitable for preparing the emulsion polymers used according to the invention are nitrogen-containing comonomers which contain N-functional groups and are polymerizable with vinyl esters. They include in particular N-ethanolic (meth) acrylamide, N-propanolic (meth) acrylamide, allyl carbamate, acrylonitrile, N-methylol of N-methylol (meth) acrylamide or allyl N-methylol-carbamate, N-alkyl ethers, Mannich bases, acrylamidoglycolic acid and/or its salts, acrylamidomethoxyacetic acid methyl ester, N- (2, 2-dimethoxy-1-hydroxyethyl) acrylamide, N-dimethylaminopropyl- (meth) acrylamide, N-methyl (meth) acrylamide, N-butyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide, N-dodecyl (meth) acrylamide, n-benzyl- (meth) acrylamide, p-hydroxyphenyl (meth) acrylamide, N- (3-hydroxy-2, 2-dimethylpropyl) methacrylamide, imidazolidinone ethyl methacrylate, N-vinylformamide and N-vinylpyrrolidone. If present, the proportion of these comonomers relative to the total amount of monomers is generally up to 15% by weight, preferably up to 10% by weight.

Other ethylenically unsaturated comonomers which are particularly suitable for preparing the emulsion polymers used according to the invention and are copolymerizable with the vinyl esters are α, β -unsaturated acids, such as acrylic acid and methacrylic acid, and their esters with primary or secondary saturated monoalcohols having from 1 to 32 carbon atoms, such as methanol, ethanol, propanol, butanol, 2-ethylhexanol, cycloaliphatic or polycyclic alcohols, and relatively long-chain fatty alcohols. It is also possible to use alpha, beta-unsaturated dicarboxylic acids (examples being maleic acid, fumaric acid, itaconic acid and citraconic acid) and their mono-or diesters with saturated monoaliphatic alcohols having from 1 to 28 carbon atoms. If present, the proportion of these comonomers relative to the total amount of monomers is generally up to 25% by weight, preferably up to 15% by weight.

Further comonomers which are particularly suitable for preparing the emulsion polymers used according to the invention are ethylenically unsaturated hydrocarbons, such as ethylene or alpha-olefins having from 3 to 28 carbon atoms (examples being propylene and/or butene) or vinylaromatic hydrocarbons (such as styrene, vinyltoluene and/or vinylxylene) and also halogenated unsaturated aliphatic hydrocarbons (examples being vinyl chloride, vinyl fluoride, vinylidene chloride and/or vinylidene fluoride). If present, the proportion of these comonomers relative to the total amount of monomers is generally up to 50% by weight, preferably up to 25% by weight.

Further comonomers which are particularly suitable for preparing the emulsion polymers used according to the invention are comonomers having a polyethylenic unsaturation and thus a crosslinking action, such as diallyl phthalate, diallyl maleate, triallyl cyanurate, tetraallyloxyethane, divinylbenzene, but-1, 4-diol dimethacrylate, triethylene glycol dimethacrylate, divinyl adipate, allyl (meth) acrylate, vinyl crotonate, methylenebisacrylamide, hexanediol diacrylate, pentaerythritol diacrylate and trimethylolpropane triacrylate, or mixtures of two or more of such compounds, may be present in the polymer. If present, the proportion of these comonomers relative to the total amount of monomers is generally up to 10% by weight, preferably up to 2% by weight.

Other comonomers which are particularly suitable for preparing the emulsion polymers used according to the invention are hydroxy-functional esters of unsaturated carboxylic acids, such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and their adducts with ethylene oxide or propylene oxide. If present, the proportion of these comonomers relative to the total amount of monomers is generally up to 25% by weight, preferably up to 15% by weight.

Further comonomers which are particularly suitable for preparing the emulsion polymers used according to the invention are self-crosslinking or carbonyl-crosslinkable comonomers selected from acetylacetonatoacrylamide, allyl acetoacetate, vinyl acetoacetate and acetoacetoxyethyl (meth) acrylate. If present, the proportion of these comonomers relative to the total amount of monomers is generally up to 10% by weight, preferably up to 5% by weight.

Another class of suitable comonomers includes monomers selected from unsaturated sulfonic acids and salts thereof (preferably vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid), epoxy-functional comonomers (such as glycidyl methacrylate and glycidyl acrylate), and silicon-functional comonomers (such as acryloxypropyltri (alkoxy) silane and methacryloxypropyltri (alkoxy) silane, vinyltrialkoxysilane and vinylmethyldialkoxysilane, where the alkoxy groups present may be, for example, ethoxy and ethoxypropylene glycol ether groups). If present, the proportion of these comonomers relative to the total amount of monomers is generally up to 10% by weight, preferably up to 5% by weight.

The comonomer units present in the copolymer in addition to the vinyl ester units may amount to up to 50% by weight in total.

Another class of emulsion polymers for polymer dispersions which can be used as polymer matrix in the dispersion adhesives of the invention comprises copolymers derived from vinylaromatic hydrocarbons and 1, 3-dienes which are prepared by free-radical emulsion polymerization and which may additionally be modified with crosslinkable monomers containing N-methylol groups.

Suitable vinylaromatic hydrocarbons are styrene, alpha-methylstyrene, vinyltoluene and/or vinylxylene. Styrene is preferably copolymerized. Examples of 1, 3-dienes are 1, 3-butadiene and isoprene. 1, 3-butadiene is preferably used in the present invention. The proportion of vinylaromatic hydrocarbon and 1, 3-diene in the total amount of monomers is at least 50% by weight.

The emulsion polymer also contains a crosslinkable N-methylol group derived from a comonomer such as N-methylolacrylamide. Also suitable are the N-methylol compounds listed above. The proportion of these comonomer fractions in the polymer based on the total amount of monomers is up to 2.0% by weight, preferably from 0.01 to 1.5% by weight, in particular from 0.05 to 1% by weight.

These copolymers may likewise comprise not only the vinylaromatic hydrocarbon and the 1, 3-diene but also further comonomers selected from the aforementioned classes (in addition to the vinylaromatic hydrocarbons already mentioned), the total amount of the further comonomer units taken together likewise being up to 50% by weight.

The polymer dispersion comprises at least one protective colloid as a stabilizer.

Examples of suitable protective colloids are polyvinyl alcohols, in particular those having a degree of hydrolysis of from 60 to 100 mol%, preferably from 70 to 98 mol%, and a viscosity of from 2 to 70 mPas at 20 ℃ in a 4% strength by weight aqueous solution. Also suitable are functional polyvinyl alcohols, for example normal copolymers of vinyl alcohol and vinyl acetate (if desired) with ethylene, with vinyl acetoacetate or isopropenyl alcohol, or those containing carboxyl groups or alkoxysilane groups.

As protective colloids, etherified cellulose derivatives may additionally be used, examples being hydroxyethyl cellulose, hydroxypropyl cellulose and carboxymethyl cellulose. They may be used alone or in combination with polyvinyl alcohol. Also suitable are polyvinylpyrrolidone, polycarboxylic acids such as polyacrylic acid and copolymers of maleic acid or maleic anhydride with ethylenically unsaturated compounds such as methyl vinyl ether or styrene. Also suitable are polyalkylene glycols or alkali metal salts of polyacrylic and polymethacrylic acids, starch derivatives and gelatin derivatives, 2-acrylamido-2-methylpropanesulfonic acid and/or 4-styrenesulfonic acid copolymers and their alkali metal salts, but also homopolymers and copolymers of the following: n-vinylpyrrolidone, N-vinylcaprolactam, N-vinylcarbazole, 1-vinylimidazole, 2-vinylpyridine, 4-vinylpyridine, acrylamide, methacrylamide, acrylates with amino groups, methacrylates, acrylamides and/or methacrylamides.

Further details of suitable protective colloids can be found in Houben-Weyl, Methodender organischen Chemie, volume XIV/I, Makromolekulare Stoffe [ macromolecular Compounds ], Georg-Thieme-Verlag, Stuttgart, 1961, pages 411 to 420. Preferably, polyvinyl alcohol is mainly used. The protective colloid fraction is preferably from 1 to 20% by weight, in particular from 2 to 14% by weight, based on the total amount of monomers.

In addition to protective colloids, it is also possible to use nonionic and/or ionic emulsifiers as costabilizers in the polymer dispersions used in the invention. If present, these co-stabilizers are generally present in an amount of up to 2% by weight, based on the total amount of the monomers. Compounds suitable for this purpose can be found in relevant information known to the person skilled in the art, for example in the Surfactant applications directory (D.R. Karsa et al, Blackie, London 1991) or Houben-Weyl, Methoden der organischen Chemie, volume XIV/I, Makromolekulare Stoffe [ macromolecular compounds ], Georg-Thieme-Verlag, Stuttgart, 1961, page 190-.

The aqueous dispersion adhesives of the present invention comprise at least one crosslinker comprising N-methylol groups fully or partially etherified with one or more alkanols and/or other hydroxyl groups fully or partially etherified with one or more alkanols selected from the group consisting of hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea, hydroxymethylated bicyclic malonaldehyde diurea, or combinations thereof.

The alkanols used for etherification are monohydric or polyhydric alcohols containing primary, secondary and/or tertiary alcohol groups. They are preferably monohydric or dihydric alcohols which contain secondary and/or, in particular, primary alcohol groups.

Preferably used is C₁～C₄₀Crosslinkers for the total or partial etherification of alkanols, where the alkanols may, if desired, contain one or more oxygen atoms in the chain, in particular with different C₁～C₄₀Crosslinkers for the complete or partial etherification of alkanols, where the alkanols may, if desired, contain one or more oxygen atoms in the chain.

Preferred at least partially etherified derivatives for use in the present invention are compounds selected from the following classes Ia to Id, wherein at least one cyclic OH group or hydroxymethyl group shown below has been etherified.

Particularly suitable are the cyclic ethylene ureas of the formula Ia

Wherein the X radicals are different or preferably identical and are hydrogen, hydroxy or C₁-C₄Alkoxy radicals such as methoxy or ethoxy, and/or

Cyclopropyleneurea of the formula Ib

Wherein Y is CH₂、CHOH、C(CH₃)₂Oxygen atom or having C₁-C₄Nitrogen atom of alkyl group, and Z is hydrogen or C₁-C₄Alkoxy radicals such as methoxy or ethoxy, and/or

Bicyclic glyoxal diurea of the formula Ic

And/or

Bicyclic malondialdehyde diurea of the formula Id

Wherein in all formulae Ia to Id the radical R¹May be the same or different and is hydrogen or C, uninterrupted or interrupted by non-adjacent oxygen atoms, unsubstituted or substituted by one or more hydroxy groups₁-C₁₀Alkyl radicals, e.g. -CH₂CH₂OCH₃、-CH₂CH₂OCH₂CH₃or-CH₂CH₂OCH₂CH₂OCH₃。

R¹Other examples of (a) include: n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, 2-ethylhexyl, and 2-methoxyethyl; of particular advantage C₁-C₃Alkyl, ethyl, n-propyl, isopropyl, especially methyl. Also advantageous are those alkyl groups having one, two, three or more hydroxyl groups and alkyl groups interrupted by oxygen.

Particularly suitable as additives for the dispersion adhesives according to the invention are at least partially etherified derivatives of 1, 3-dimethylol-4, 5-dihydroxyethylene urea (DMDHEU), in which the nitrogen atoms of the imidazolidinone ring are each substituted symmetrically or, in particular, asymmetrically (etherified).

Preferably one of the two methylol groups of DMDHEU is etherified with a methyl group, while the other isOne methylol group is derivatized by reaction with a polyol selected from the group consisting of ethylene glycol, diethylene glycol, 1, 2-and 1, 3-propanediol, 1, 2-, 1, 3-and 1, 4-butanediol, glycerol and a polyol of the formula HO (CH)₂CH₂O)_nH (wherein 3. ltoreq. n.ltoreq.20), preferably diethylene glycol. Such asymmetrically substituted DMDHEU is described, for example, in WO-A-98/29,393.

The crosslinking agent is used in an amount of usually 0.001 to 4% by weight, preferably 0.01 to 2% by weight, based on the solid content of the emulsion polymer.

Such compounds are commercially available, for example from Clariant GmbH under the trade name ® Arkofix. Among these, ® Arkofix NEC plus conc. is a particularly suitable product.

The dispersion adhesives of the invention comprise a crosslinking catalyst as well as a polymer dispersion and a crosslinking agent. These catalysts may be free acids or, preferably, acidic metal salts. Salts suitable for this purpose are those having polyvalent coordinatable cations, as described, for example, in DE-B-2261402, DE-C-2620738 and DE-A-3942628.

Preference is given to using water-soluble metal salts of Al (III) or Zr (IV), in particular aluminum chloride, aluminum nitrate, zirconium oxychloride and/or zirconium nitrate.

The amount of these crosslinking catalysts is generally from 0.05 to 10% by weight, preferably from 0.1 to 8% by weight, based on the amount of dispersion binder.

To improve the water-repellent properties, it is also possible to use further salts or additives, for example magnesium chloride, organic and/or inorganic acids (such as citric acid, glycolic acid), or acidic inorganic salts (such as sodium tetrafluoroborate).

The amount of these additional salts or additives is generally from 0.05 to 10% by weight, preferably from 0.1 to 5% by weight, based on the amount of dispersion binder.

The optimum pH range for crosslinking is preferably 2 to 6, in particular 2.5 to 4. The appropriate pH value can be obtained immediately after the emulsion polymerization or preferably subsequently by addition of the abovementioned acidic compounds.

The aqueous polymer dispersions may contain further customary additives, examples being film-forming auxiliaries for reducing the minimum film-forming temperature (MFFT), plasticizers, defoamers, fillers and preservatives.

The solids content of the aqueous dispersion adhesive of the invention is preferably 20 to 65% by weight, in particular 30 to 63% by weight.

A preferred embodiment of the aqueous dispersion adhesive of the present invention comprises:

a) copolymers based on one or more polyvinyl esters, preferably on polyvinyl acetate, which additionally comprise, based on the total amount of all monomers, from 0.01 to 1.5% by weight, preferably from 0.01 to 1% by weight, of one or more crosslinkable comonomer units containing N-methylol groups, preferably derived from N-methylol (meth) acrylamide,

b) 1 to 20 wt.%, based on the total amount of all monomers, of at least one protective colloid, preferably polyvinyl alcohol,

c) 0.001 to 1 wt.%, based on the amount of the polymer dispersion, of at least one derivative at least partially etherified with one or more alkanols, selected from the group consisting of hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea, or hydroxymethylated bicyclic malondialdehyde diurea, and

d) at least one acidic metal salt and/or acid in an amount sufficient to achieve a pH of 2 to 6, preferably 2.5 to 4. Another preferred embodiment of the aqueous dispersion adhesive of the present invention comprises:

e) copolymers based on one or more polyvinyl esters, preferably based on polyvinyl acetate, which additionally comprise, based on the total amount of all monomers, from 0.01 to 1.5% by weight, preferably from 0.01 to 1% by weight, of one or more comonomer units containing crosslinkable N-methylol groups, preferably derived from N-methylol (meth) acrylamide, and from 0.01 to 3.0% by weight, based on the total amount of all monomers, of one or more further functional comonomer units derived from etherified N-methylol monomers, unsaturated carboxylic acids and/or OH-functional esters of unsaturated carboxylic acids,

f) 1 to 20 wt.%, based on the total amount of all monomers, of at least one protective colloid, preferably polyvinyl alcohol,

g) 0.001 to 1 wt.%, based on the amount of aqueous dispersion binder, of at least one at least partially etherified derivative selected from the group consisting of hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea and hydroxymethylated bicyclic malondialdehyde diurea, and

h) at least one acidic metal salt and/or acid in an amount sufficient to achieve a pH of 2 to 6, preferably 2.5 to 4.

Another preferred embodiment of the aqueous dispersion adhesive of the present invention comprises: 0.001 to 1 wt.%, based on the amount of aqueous dispersion binder, of at least one at least partially etherified, preferably asymmetrically partially etherified derivative selected from the group consisting of hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea and hydroxymethylated bicyclic malondialdehyde diurea.

The invention also provides a process for preparing the aqueous dispersion adhesive of the invention.

The aqueous polymer dispersions are usually prepared by emulsion polymerization, the polymerization temperature generally being from 40 to 100 ℃, preferably from 60 to 90 ℃, in particular from 62 to 85 ℃.

The initiation of the polymerization reaction employs initiators or redox initiator compositions customary for emulsion polymerization, examples being hydroperoxides (e.g.tert-butyl hydroperoxide), azo compounds (e.g.azobisisobutyronitrile) and inorganic initiators (e.g.sodium, potassium and ammonium salts of peroxodisulfuric acid). These initiators are generally used in amounts of 0.05 to 3.5% by weight, based on the total weight of the monomers.

As redox initiators, combinations of the aforementioned initiators with reducing agents, such as sodium sulfite, sodium hydroxymethanesulfinate or ascorbic acid, are used if desired. The amount of the reducing agent is preferably 0.01 to 5.0 wt% based on the total weight of the monomers.

The polymeric ingredients are stabilized predominantly by the abovementioned protective colloids, if appropriate with the addition of emulsifiers, but preferably without emulsifiers.

The protective colloid and, if used, the emulsifier are preferably partly contained in the starting material. However, it is also possible to add the protective colloid portion and the emulsifier, if used, before, during or after the polymerization.

The monomers may be contained in their entirety in the initial charge, metered in their entirety, or partly in the initial charge, the remainder being metered in after initiation of the polymerization.

When the polymerization is complete, post-polymerization to remove residual monomers can be carried out using known methods, examples being post-polymerization initiated by redox catalysts. Volatile residual monomers can also be removed by distillation, preferably under reduced pressure, and, if desired, by passing an inert entraining gas, for example air, nitrogen or steam, through or over the product.

When the polymerization is complete and, if applicable, the demonomerization is carried out, the dispersion is mixed, if necessary, with at least one acid metal salt and/or acid in an amount sufficient to obtain a suitable pH and with at least one derivative selected from the group consisting of hydroxymethylated ethyleneurea, hydroxymethylated propyleneurea, hydroxymethylated bicyclic glyoxal diurea or hydroxymethylated bicyclic malondialdehyde diurea which is partially or totally etherified with an alkanol.

Other additives may be added to the polymer dispersion during processing in the end use, examples being film forming aids, plasticizers, defoamers, fillers and preservatives which can be used to reduce MFT. Any desired combination in terms of order of addition is allowed within the scope of the invention.

The present invention accordingly provides a process for preparing the above-described aqueous dispersion adhesive, which comprises the steps of:

i) aqueous emulsion polymerization of free-radically polymerizable monomers in the presence of protective colloids, at least one of which contains crosslinkable N-methylol groups and is present in an amount of up to 2.0% by weight, based on the total amount of monomers, in a conventional manner, and

ii) after the preparation of the aqueous emulsion polymer, at least one crosslinking agent containing N-methylol groups which are fully or partially etherified with one or more alkanols and/or other hydroxyl groups which are fully or partially etherified with one or more alkanols is added, selected from the group consisting of hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea or hydroxymethylated bicyclic malondialdehyde diurea or a combination thereof.

The amount of the copolymerized N-methylol compound in the aqueous dispersion adhesive of the present invention is reduced, and therefore the aqueous dispersion adhesive can be industrially produced at a lower processing cost. However, they have comparable or improved cold water resistance properties compared to conventional binders and at the same time have comparable or reduced formaldehyde content. They therefore achieve a durability of at least D3 level according to DIN EN 204 test standard and often significantly exceed 2N/mm²Preferably more than at least 50%.

The dispersion adhesives of the invention may be treated in conventional manner by applying them to at least one surface of the substrates to be bonded and bonding the substrates.

The invention also provides for the use of the dispersion adhesives of the invention for adhesively bonding substrates, preferably porous and semi-porous substrates.

The particular suitability of the dispersion adhesive of the invention lies in its use as a cold water resistant adhesive, in particular for cellulosic substrates such as wood.

The adhesive is suitable for do-it-yourself applications or as an industrial adhesive for mechanical gluing and is particularly suitable for applications where the bonding is cured by high frequency alternating current.

They are particularly suitable for cold water resistant adhesives which require the use of relatively high characteristic curves.

Examples of other general applications are waterproof gluing for producing paper, cardboard, including corrugated cardboard, foam, cement, leather, textiles or compressed sheets.

Other applications include use as adhesives for the construction sector, for example for floors, walls or ceilings, or as adhesives for furniture finishes (furniture foils) or for carpet backings.

Other areas of application are their use as waterproofing adhesives for wood fibre boards or recycled leather, as well as adhesives for insulating materials, including paper or polymer fibres, and additionally as adhesives for plasters or cements in waterproofing building dispersions.

Other fields of application are as binders for textile sheets and nonwovens, in textile printing and as textile finishing agents.

Examples

The following examples serve to illustrate the invention. Parts and percentages in the examples are by weight unless otherwise indicated.

Preparation of the polymer dispersions of inventive examples 1 to 8 and comparative examples C1 to C4.

The experimental set-up comprised a 3 liter cylindrical glass reactor with an anchor stirrer (130rpm) equipped with a metering vessel, reflux condenser, heating and cooling jackets and temperature measurement and control means. A polymerization mixture was first prepared from 93 parts (or 94.5 parts in dispersions A and C) of deionized water, 7.2 parts of a partially hydrolyzed polyvinyl alcohol having a viscosity of 18 mPas at 88 mol% H ö in a 4% strength aqueous solution (at 20 ℃), 1.8 parts of a partially hydrolyzed polyvinyl alcohol having a viscosity of 40 mPas at 88 mol% H ö in a 4% strength aqueous solution (at 20 ℃), and 0.05 part of anhydrous sodium acetate. To this mixture, 0.12 part of a defoamer ® Agitan 301 (Munzing-Chemie) and 0.035 part of sodium bicarbonate were added before starting the reaction. The internal temperature was raised to 65 ℃ and polymerization was initiated by adding 7.2 parts of vinyl acetate and 0.02 parts of ammonium peroxodisulfate in 0.15 parts of water.

After the reaction started, three feed streams were started. The first feed stream consisted of the remainder of the total amount of vinyl acetate shown in table 1 and further included the amount of Isobutoxymethacrylamide (IBMA) shown in table 1, where appropriate (for the case of dispersions C, D and G). The second feed stream consisted of an aqueous solution of N-methylolacrylamide (NMA). This solution was prepared from a commercial solution of the monomer (48% strength) by dilution with deionized water (see data in table 1). The third feed stream consisted of 0.03 parts ammonium peroxodisulfate solution in 8 parts deionized water. These feed streams were metered simultaneously in parallel over a period of 3.5 hours. The polymerization temperature was 80. + -. 2 ℃. Subsequent postpolymerization was carried out at 80 ℃ by adding in addition 0.01 part of ammonium peroxodisulfate in 0.03 part of water and at 50 ℃ by adding 0.05 part of tert-butyl hydroperoxide in 0.15 part of water and 0.05 part of sodium metabisulfite in 0.15 part of water. The solids content of the dispersion was 50.2. + -. 0.2% and the residual vinyl acetate content was less than 3000 ppm.

TABLE 1

Dispersion product	A	B	C	D	E	F	G	H	I	J
											Fraction of vinyl acetate	99.90	99.25	98.90	98.75	99.50	99.75	99.25	99.00	98.00	98.50
Number of NMA	0.1	0.75	0.1	0.25	0.5	0.25	0.25	1.00	2	1.5
											Parts of water for NMA feed stream	4.5	6	4.5	6	6	6	6	6	6	6
Parts of IBMA	0	0	1	1	0	0	0.5	0	0	0

Inventive examples 1 to 8 and comparative examples C1 to C4

100 parts of the polymer dispersion are first mixed with 2 parts of butyldiglycol acetate (as film former) and with 3 parts of 54% strength aluminum chloride hexahydrate solution (as acidic crosslinking catalyst). The pH of the dispersion was 2.8. + -. 0.1.

The formulated dispersions were then mixed in inventive examples 1 to 8 with ® Arkofix EC PLUS conc. (product of Clariant GmbH) in the amounts shown in Table 2, and the formulated dispersions were mixed in comparative example C4 with an approximate amount of ® Arkofix NG conc. (product of Clariant GmbH). The percentages are based on the dispersion already containing the film-forming agent and the acidic metal salt. Based on N, N' -dimethylol dihydroxy ethylene urea (DMDHEU), ® Arkofix NEC reuscon. is an asymmetric mixed ether of methanol and diethylene glycol. On the other hand, the co-tested crosslinker ® Arkofix NG conc. for comparison purposes was non-etherified DMDHEU.

The wet bond strength of the adhesive on the beech test specimens after 4 days of cold water treatment was determined according to DIN EN 204/D3 test standard.

The test specimens were prepared according to the method of DIN EN 205. Gluing and testing were performed under the following key data:

application of the adhesive: 150 +/-20 g/m²(ii) a Double-sided application

Open latency: 3 minutes

Closing the waiting time: 3 minutes

Pressing time: 2 hours

The pressing pressure is 0.7 +/-0.1N/mm²

Number of test samples per test procedure 10

Test is carried out for 7 days^*)

Storage according to DIN EN 204D3/3 in cold water (20. + -. 5 ℃) for 4 days

The procedure is as follows:

and (3) testing temperature: 23 + -2 deg.C

The advancing speed is 50mm/min.

^*) 23. + -. 2 ℃ and 50. + -. 5% relative humidity

(tensile strength is more than or equal to 2N/mm)²Time is divided into D3/3 level durability)

The results obtained are shown in table 2. The table also contains the viscosity data of the dispersion (Brookfield viscometer at a test temperature of 23 ℃, RVT test system, spindle 6 (in the range of up to 50 Pa.s) or spindle 7 (in the range of 50 to 200 Pa.s)) and the viscosity after storage at 50 ℃ for 10 days.

TABLE 2

Examples	Preparation from dispersions	Comonomer 1	Comonomer 2	Fraction of crosslinker resin	Viscosity Pa s	Viscosity Pa.s after 10 days at 50 DEG C	D3/3N/mm2
								1	A	0.1％NMA	-	0.50ArkofixNEC	20.05	62.40	3.5
2	B	0.75％NMA	-	0.25ArkofixNEC	18.55	72.80	4.0
								3	C	0.1％NMA	1％IBMA	0.25ArkofixNEC	24.10	49.80	3.7
4	D	0.25％NMA	1％IBMA	0.25ArkofixNEC	21.75	101.60	3.5
								5	E	0.5％NMA	-	0.25ArkofixNEC	20.45	50.80	3.5
6	F	0.25％NMA	-	0.25ArkofixNEC	20.15	54.00	3.3
								7	G	0.25％NMA	0.5％IBMA	0.25ArkofixNEC	20.35	66.40	3.2
8	H	1％NMA	-	0.25ArkofixNEC	21.00	103.40	3.5
								C1	I	2％NMA	-	-	33.90	1)	4.0
C2	J	1.5％NMA	-	-	28.20	1)	4.0
								C3	B	0.75％NMA	-	-	29.35	70.20	2.9
C4	I	1％NMA	-	0.25ArkofixNG	23.45	1)	6.2

1) The sample was not tested because it was fully crosslinked.

2N/mm exceeding the minimum wet bond strength standard can be obtained by the embodiment of the invention²At least 50% of the preparation. At the same time, it is possible to achieve a reduction in the amount of copolymerized N-methylol monomers in comparison with comparative examples C1, C2 and C4. With example 3 (2.9N/mm) containing 0.75% NMA and below the desired limit²) In direct comparison, example 2 shows that the addition of Arkofix NEC PLUS conc. results in a significant increase in wet bond strength for a given amount of NMA.

Comparative example C4, in which a non-etherified DMDHEU was used, did therefore give high bond strength due to its high reactivity; however, it did not give a storage stable product as compared with example 8 containing the same amount of copolymerizable N-methylol monomer.

Claims (27)

1. An aqueous dispersion adhesive based on a polymer dispersion comprising at least one emulsion polymer containing crosslinkable N-methylol groups, wherein the N-methylol groups are obtained by adding up to 2.0% by weight, based on the total amount of monomers, of comonomers containing N-methylol groups to the emulsion polymer, and at least one protective colloid and at least one crosslinking agent containing N-methylol groups which are fully or partially etherified with one or more alkanols and/or further hydroxyl groups which are fully or partially etherified with one or more alkanols, the crosslinking agent being selected from the group consisting of: hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea, hydroxymethylated bicyclic malondialdehyde diurea, or a combination thereof.

2. The aqueous dispersion adhesive according to claim 1, wherein the emulsion polymer used comprises a crosslinkable N-methylol group obtained by adding 0.01 to 1.5% by weight, based on the total amount of monomers, of a comonomer containing an N-methylol group.

3. The aqueous dispersion adhesive according to claim 2, wherein the emulsion polymer used comprises crosslinkable N-methylol groups obtained by adding 0.05 to 0.8% by weight, based on the total amount of monomers, of a comonomer containing N-methylol groups.

4. The aqueous dispersion adhesive according to claim 1, wherein the emulsion polymer used is based predominantly on vinyl esters as main monomers and wherein up to 2.0% by weight, based on the total amount of monomers, of comonomers which contain crosslinkable N-methylol groups are present.

5. The aqueous dispersion adhesive according to claim 4, wherein the vinyl ester is selected from the group consisting of vinyl formate, vinyl acetate, vinyl propionate, vinyl isobutyrate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl esters of saturated branched monocarboxylic acids having 9 to 11 carbon atoms in the acid residue, vinyl laurate or stearate, vinyl esters of benzoic acid, and vinyl esters of substituted derivatives of benzoic acid, and wherein the proportion of vinyl esters in the copolymer to the total amount of monomers is at least 50% by weight.

6. The aqueous dispersion adhesive according to claim 1, wherein an emulsion polymer is used, wherein the comonomer containing N-methylol groups is selected from the group consisting of N-methylolacrylamide, N-methylolmethacrylamide, allyl N-methylolcarbamate, N-methylolmaleimide, N-methylolmaleamic acid, and N-methylolamide of aromatic vinyl carboxylic acids, and wherein the proportion of these comonomers in the total amount of monomers is 0.01 to 1.5% by weight.

7. The aqueous dispersion adhesive according to claim 4, wherein the emulsion polymer used is derived, in addition to the vinyl ester-based monomer and the comonomer containing a crosslinkable N-methylol group, from at least one further comonomer selected from the group consisting of: nitrogen-containing comonomers which are copolymerizable with vinyl esters and contain N-functional groups, esters of alpha, beta-unsaturated monocarboxylic acids and of these with primary or secondary saturated monoalcohols, cycloaliphatic alcohols or polycyclic alcohols and relatively long-chain aliphatic alcohols having from 1 to 32 carbon atoms, mono-or diesters of alpha, beta-unsaturated dicarboxylic acids and of these with saturated monoaliphatic alcohols having from 1 to 28 carbon atoms, ethylenically unsaturated hydrocarbons, vinylaromatic hydrocarbons, halogenated unsaturated aliphatic hydrocarbons, polyethylenically unsaturated comonomers, hydroxy-functional esters of unsaturated carboxylic acids, self-crosslinking or carbonyl-crosslinkable monomers from the group of acetylacetonateacrylamides, comonomers of allyl acetoacetate, vinyl acetoacetate and acetoacetoxyethyl (meth) acrylate, unsaturated sulfonic acids and/or salts thereof, epoxy-functional comonomers and/or silicon-functional comonomers.

8. The aqueous dispersion adhesive according to claim 1, wherein the emulsion polymer used is a copolymer derived from a vinylaromatic hydrocarbon and a 1, 3-diene and modified with a monomer containing a crosslinkable N-methylol group.

9. The aqueous dispersion adhesive according to claim 7, wherein the vinyl aromatic hydrocarbon is selected from styrene, alpha-methylstyrene, vinyltoluene and/or vinylxylene, wherein the 1, 3-diene is selected from 1, 3-butadiene and/or isoprene.

10. The aqueous dispersion adhesive according to claim 1, wherein the protective colloids are selected from the group consisting of polyvinyl alcohols, copolymers of vinyl alcohol and, if desired, vinyl acetate with ethylene, with vinyl acetoacetate or isopropenyl alcohol, copolymers of vinyl alcohol with monomers containing carboxyl or alkoxysilane groups, etherified cellulose derivatives, polyvinylpyrrolidone, polycarboxylic acids, copolymers of maleic acid or maleic anhydride with ethylenically unsaturated compounds, polyalkylene glycols, alkali metal salts of polyacrylic and polymethacrylic acids, starch derivatives and gel derivatives, copolymers of 2-acrylamido-2-methylpropanesulfonic acid and/or 4-styrenesulfonic acid and their alkali metal salts, and homopolymers and copolymers of: n-vinylpyrrolidone, N-vinylcaprolactam, N-vinylcarbazole, 1-vinylimidazole, 2-vinylpyridine, 4-vinylpyridine, acrylamide, methacrylamide, acrylates with amino groups, methacrylates, acrylamides and/or methacrylamides.

11. The aqueous dispersion adhesive of claim 10, wherein the protective colloid is polyvinyl alcohol.

12. The aqueous dispersion adhesive of claim 1, wherein the crosslinker is selected from the following compounds:

cyclic ethylene ureas of the formula Ia

Wherein the radicals X are different or identical and are hydrogen, hydroxy or C₁-C₄Alkoxy, and/or

Cyclopropyleneurea of the formula Ib

Wherein Y is CH₂、CHOH、C(CH₃)₂Oxygen atom or having C₁-C₄The nitrogen atom of the alkyl group or the nitrogen atom of the alkyl group,

and Z is hydrogen orC₁-C₄Alkoxy, and/or

Bicyclic glyoxal diurea of the formula Ic

And/or

Bicyclic malondialdehyde diurea of the formula Id

Wherein in all formulae Ia to Id the radical R¹May be the same or different and is hydrogen or C, uninterrupted or interrupted by non-adjacent oxygen atoms, unsubstituted or substituted by one or more hydroxy groups₁-C₁₀An alkyl group.

13. The aqueous dispersion adhesive according to claim 12, wherein the crosslinker is an ethylene-based urea of the general formula Ia, which is an at least partially etherified derivative of 1, 3-dimethylol-4, 5-dihydroxyethylene urea, wherein the nitrogen atoms of the imidazolidinone ring are all etherified symmetrically or in particular asymmetrically.

14. The aqueous dispersion adhesive of claim 13, wherein one of the two methylol groups of 1, 3-dimethylol-4, 5-dihydroxyethylene urea is etherified with a methyl group and the other methylol group is etherified by reaction with a polyol selected from the group consisting of ethylene glycol, diethylene glycol, 1, 2-and 1, 3-propanediol, 1, 2-, 1, 3-and 1, 4-butanediol, glycerol, and a polyol having the formula HO (CH)₂CH₂O)_nH, wherein n is an integer between 3 and 20.

15. The aqueous dispersion adhesive according to claim 1, which has a pH of 2.5 to 4.

16. The aqueous dispersion adhesive of claim 1, comprising

a) Copolymers based on one or more polyvinyl esters which additionally comprise from 0.01 to 1.5% by weight, based on the total amount of all monomers, of one or more crosslinkable comonomer units containing N-methylol groups,

b) 1 to 20% by weight, based on the total amount of all monomers, of at least one protective colloid,

c) 0.001 to 1 wt.%, based on the amount of the polymer dispersion, of at least one derivative partially or completely etherified with one or more alkanols, selected from the group consisting of hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea or hydroxymethylated bicyclic malondialdehyde diurea, and

d) at least one acidic metal salt and/or acid in an amount sufficient to achieve a pH of 2 to 6.

17. The aqueous dispersion adhesive of claim 1, comprising

e) Copolymers based on one or more polyvinyl esters, which additionally comprise, based on the total amount of all monomers, from 0.01 to 1.5% by weight of one or more comonomer units containing crosslinkable N-methylol groups and from 0.01 to 3.0% by weight, based on the total amount of all monomers, of one or more further functional comonomer units derived from etherified N-methylol monomers, unsaturated carboxylic acids and/or OH-functional esters of unsaturated carboxylic acids,

f) 1 to 20% by weight, based on the total amount of all monomers, of at least one protective colloid,

g) 0.001 to 1 wt.%, based on the amount of aqueous dispersion binder, of at least one derivative selected from the group consisting of hydroxymethylated ethyleneurea, hydroxymethylated propyleneurea, hydroxymethylated dicyclo-glyoxal diurea and hydroxymethylated dicyclo-malonaldehyde diurea partially or completely etherified with one or more alkanols, and

h) at least one acidic metal salt and/or acid in an amount sufficient to achieve a pH of 2 to 6.

18. The aqueous dispersion adhesive according to claim 1, wherein the crosslinker fraction is from 0.001 to 1% by weight, based on the amount of aqueous dispersion adhesive.

19. A process for preparing the aqueous dispersion adhesive of claim 1, comprising the steps of:

i) aqueous emulsion polymerization of free-radically polymerizable monomers in the presence of protective colloids, at least one of which contains crosslinkable N-methylol groups and is present in an amount of up to 2.0% by weight, based on the total amount of monomers, in a conventional manner, and

ii) after the preparation of the aqueous emulsion polymer, at least one crosslinking agent containing N-methylol groups which are fully or partially etherified with one or more alkanols is added, selected from the group consisting of hydroxymethylated cyclic ethylene urea, hydroxymethylated cyclic propylene urea, hydroxymethylated bicyclic glyoxal diurea or hydroxymethylated bicyclic malondialdehyde diurea or combinations thereof.

20. Use of the aqueous dispersion adhesive according to claim 1 for adhesively bonding porous and semi-porous substrates.

21. Use according to claim 20, wherein the porous and semi-porous substrates are cellulosic substrates.

22. Use according to claim 20, wherein the porous and semi-porous substrates are selected from paper, cardboard, foam, cement, leather, fabric and compressed sheets.

23. Use according to claim 22, wherein the paperboard is corrugated board.

24. Use of the aqueous dispersion adhesive according to claim 1 as an adhesive for the construction sector.

25. Use according to claim 24, wherein the adhesive for the construction sector is as an adhesive for floors, walls or ceilings or for furniture surfacing or for carpet backing.

26. Use of the aqueous dispersion adhesive according to claim 1 as an adhesive for wood fibre boards or for recycled leather, for insulating materials for paper or polymer fibres, or as an adhesive for plaster or cement.

27. Use of the aqueous dispersion binder according to claim 1 as a binder for textile sheets and nonwovens, or as a textile finish or in textile printing.