NO160662B - FORMALDEHYDE-FREE VAN BASIS OF A CRY-BINDABLE POLYMETHER FOR ITS MANUFACTURING AND USING IT. - Google Patents

Abstract

1. Claims for the Contracting states : BE, CH, DE, FR, GB, IT, LI, NL, SE Formaldehyde-free aqueous plastics dispersions based on a crosslinkable polymer of ethylenically unsaturated monomers containing N-methylolamide and/or N-methylol ether-amide groups, characterized in that the dispersions contain a compound of the formula I see diagramm : EP0143175,P11,F1 in which n = 0 or 1, N = oxygen, -CH2 -, -CH(R)- or -N(R)-, R representing (C1 -C4 )-alkyl or (C1 -C4 )-alkylol, and R**1 and R**2 denote H or OH. 1. Claims for the Contracting state : AT Process for the preparation of formaldehyde-free aqueous plastics dispersions based on a crosslinkable polymer of ethylenically unsaturated monomers containing N-methylolamide and/or N-methylol ether-amide groups, characterized in that aqueous crosslinkable polymer dispersions containing N-methylolamide and/or N-methylol ether-amide groups, prepared in the usual manner, are mixed with a compound of the formula 1 see diagramm : EP0143175,P12,F1 in which n = 0 or 1, X = oxygen, -CH2 -, -CH(R)- or -N(R)- R representing (C1 -C4 )-alkyl or (C1 -C4 )-alkylol, and R**1 and R**2 denote H or OH.

Description

The invention relates to a storage-stable, aqueous plastic dispersion based on a crosslinkable polymer of ethylenically unsaturated monomers with a content of N-methyloamide and/or N-methyloletheramide groups, which contains a cyclic urea compound, preferably ethylene urea, as formaldehyde acceptor which practically completely binds in dispersion with possibly present or formed by splitting formaldehyde, so that the dispersion without

effect of the cross-linkability as well as the polymer films produced from this are highly formaldehyde-free and thus physiologically harmless. The invention further relates to a method for producing said formaldehyde-free dispersion as well as its use.

In the production of fluorescent materials for disposable, respectively disposal items as well as for permanent items, to-

regardless of manufacturing methods, as well as when using natural as well as synthetic fibres, plastic dispersions are especially important as binders for increasing the mechanical stressability and also for improving the grip.

Thus, non-wovens are required as disposal articles in the sanitary, hygiene and household areas if sufficient

good application properties after the fiber treatment with finishing agents a high wet tear resistance<p>t.

It is further in the foreground, e.g. for the area of clothing, in households, high-rise buildings and automobile construction, in addition to the firmness properties of fluorescent substances, their cleaning resistance to water and solvents.

The required mechanical properties as well as the resistance to cleaning can be particularly advantageously realized with the use of plastic dispersions with cross-linking groups. The cross-linking of the plastic dispersion possibly advantageous presence of catalyst such as acids or salts, leads to a three-dimensional molecular increase in the polymer components, which means greater resistance of the products to mechanical stress and higher insensitivity when treated with water and solvents.

It is about the plastic dispersions relevant here

predominantly polymers based on vinyl acetate, vinyl propionate, acrylic acid ester, ethylene, styrene, branched aliphatic carboxylic acid vinyl esters (preferably with carboxylic acid esters of 4 - 18 C atoms), vinyl chloride, acrylamide, acrylic acid, acrylonitrile, methacrylic acid, methacrylamide and similar ethylenically unsaturated monomers, in that for building up the desired polymer properties, copolymer combinations of the listed monomers with such comonomers, which contain the groups suitable for cross-linking reactions, are preferably used.

As cross-linkers, components containing methylol groups are mainly used. Polymer parts with basic molecular units of N-methylol derivatives of unsaturated organic acid amides, such as e.g. N-methylol acrylamide

(NMAA) and/or their alkyl or aryl ethers, such as e.g. N-(iso-butoxy-methyl)-acrylamide (IBMA). Cross tie off

this type, however, has the property, if they contain free methylpl groups in situ or such are formed by splitting their derivatives in an aqueous acidic environment, to a small extent split off formaldehyde, as an equilibrium is established that lies very strongly on the side of those embedded in polymerized methylol groups. The cross-linking of the dispersion polymer over methylol groups takes place during and after evaporation of water in the temperature range from 80°C to 250°C, preferably 120°C to 180°C, depending on the duration of the temperature effect and a substrate temperature that has been achieved. Polymer film after cross-linking is, like the starting dispersion, practically free of formaldehyde. They mentioned

methylol group-containing cross-linking components above all have the advantage that, in the case of cross-linked polymers, they lead to the desired improvements with regard to the mechanical properties of the film and coatings as well as their solvent resistance, without thereby losing the macromolecular structure and the properties of the cross-linked product due to the polymer. Thus, the properties of such cross-linked dispersion polymer-treated bulk materials such as e.g. soft/hard grip, boiling ability, malleability, sealing ability, etc.

The disadvantage, however, is the setting of the equilibrium in the aqueous phase formed proportion of free formaldehyde and only to a small extent which, due to its odor and irritating effect on eyes and mucous skin, can already be observed in very small concentration and thus in the production of fluorescent substances of any type, e.g. .a. especially for toxicological reasons must be seen. In addition, for the use of the binder system for the production of fluorescent substances for sanitary and hygiene areas in the sub-sector of the application, there is a requirement that only formaldehyde-free plastic dispersion systems must be used.

The aim of the invention is thus to build up a plastic dispersion system which has the known basic properties of non-wovens for bonding, with good cross-linking character, but the methylol groups incorporated in the polymer at equilibrium in the aqueous phase-conditioned part of free formaldehyde bind themselves in situ or by film formation in statu nascendi on a reactive component. The mixture must be capable of stable storage and, like standard synthetic resin dispersions, can be processed according to the various methods of fluorine fixing. In addition, the reactivities with regard to cross-linking and formaldehyde binding must be maintained under the usual storage and processing conditions for plastic dispersions.

To reduce the content of free formaldehyde, when preparing the fluorine substances for the technical as well as for the hygiene area in cross-linkable aqueous plastic dispersions are added when they are used, usually already reactive components such as urea, thiourea, melamine and others are used. However, due to compatibility and reactivity, these additives are only added to the overall system immediately before processing and are also omitted in many cases due to non-fulfillment of the complex spectrum of requirements for fluff binding.

For use in plastic dispersions that are used to bind the fluorine for the hygiene and sanitary area, these additives must, like the polymer, correspond to the physiological requirements and must also be soluble or dispersible in water.

It was now surprisingly found that aqueous synthetic dispersions containing N-methylol group as well as

the polymerizate films produced therefrom can be made highly formaldehyde-free when urea derivatives are added to the dispersions, especially cyclic urea compounds, preferably ethylene urea (=imidazolidin-2-one). The binding of formaldehyde takes place by transferring the urea compounds added according to the invention into the N- and N'-methylol compounds respectively, as the reaction equilibrium in the aqueous acid phase is practically completely on the side of N- and The N'-methylol compound.

From the European Patent Application No. 0 043 036/A 1 it was already known that ethylene urea as an additive during curing of acid-curing alkyd resin-urea-resin combinations can be used to reduce the occurring emission of formaldehyde. The addition of the urea therefore takes place immediately before processing the varnish, preferably at the same time as the acid catalyst, and is thus a so-called two-holding system with a non-aqueous organic solution. As an acid-hardening plasticized urea/formaldehyde resin component, a commercially available 60 percent by weight resin solution in ethanol/butanol is used for the production of the 1- or 2-component varnish for the industrial surface treatment of wood and wood materials.

The object of the invention is now a formaldehyde-free aqueous plastic dispersion based on a cross-linkable polymer of ethylenically unsaturated monomers with a content of N-methylolamide and/or N-methylol ether amide groups, the dispersion being characterized by containing a compound of formula I,

where n = 0 or 1,

X = oxygen, -CH2-, -CH(R)- or -N(R)-, where R means (C1-<C>4)-alkyl or (C1-C4)-alkylol,

and

R<1>, R2 = H or OH.

The dispersion may also contain ordinary acid and/or acid emitters, preferably organic acids and/or organic acid emitters, and the dispersion's pH value is preferably in

the acidic range, especially at pH 1.5 to 6. Dispers-

The solids content of the solution is not subject to special restrictions and can move within the usual limits for aqueous plastic dispersions. Preferably they are in the range from 15 to 65% by weight, especially at 30 to 55% by weight.

The content of the compound for formula I is variable and can amount to up to 10% by weight referred to dispersion.

However, it must at least be equivalent to the amount of formaldehyde to be bound. Preferably it amounts to 0.15

to 6% by weight, especially 0.3 to 3% by weight referred to dispersion.

A particularly preferred compound of formula I is that

known as ethyleneurea imidazolidin-2-one.

Further compounds of formula I are e.g. dihydroxyethylene urea, propylene urea, triazinones, urones.

Such crosslinkable plastic dispersions are also preferred if the polymerized part contains all basic molecular units of ethylenically unsaturated monomers from the group of vinyl acetate, vinyl propioate, acrylic acid ester, maleic acid monoester, maleic acid diester, styrene, ethylene, vinyl ester and long-chain linear or branched carboxylic acid, vinyl chloride, acrylamide , acrylic acid, acrylonitrile, methacrylic acid, methacrylamide, if possible combination to copolymers or terpolymers as common basic molecular units with preferably suitable N-methylolamide and/or N-methyloletheramide groups.

The content of the basic molecular unit with the N-methylolamide and/or N-methyloletheramide groups suitable for crosslinking in the polymerizate part of the dispersion is not critical and can assume all common values with crosslinkable plastic dispersions. Preferably, however, 0.2 to 6 percent by weight, in particular 1.5 to 4 percent by weight, refers to the polymer.

A particularly preferred basic molecular unit with an N-methylolamide group suitable for cross-linking is that of N-methylolacrylamide.

Equally preferred are methylol isobutyl ether of N-methylol acrylamide as well as N-methylol methacrylamide and its N-methylol-(C1-C4)-alkyl ether.

A further object of the invention is a method for the production of the above-mentioned formaldehyde-free aqueous plastic dispersions on the basis of a cross-linkable polymer of ethylenic unsaturated monomers with a content of N-methylolamide and/or N-methyloletheramide groups, the method being characterized in that conventionally produced aqueous , crosslinkable and N-methylolamide- and/or N-methyloletheramide group-containing polymer dispersions are mixed with compound of formula I.

The compounds of formula I are added to the dispersion preferably as an alcoholic solution. Particularly preferably, a 20 to 50% by weight, especially 30% by weight solution of compound of formula I in ethanol is used. Surprisingly, the compounds of formula I can be incorporated without any problems into the above-mentioned crosslinkable aqueous polymer dispersions. The resulting mixtures according to the invention are stable under normal storage conditions at room temperature for up to several months also in the presence of other organic acids or acid emitters. Also, the basic properties of dispersions, namely the cross-linkability of their polymerizate constituents and the reactivity towards formaldehyde are fully maintained even in the presence or subsequent formation of the latter in the smallest concentrations. Achieving this spectrum of properties is one essential prerequisite for the applicability of the compounds of formula I as modifiers in crosslinkable plastic dispersions for treating, for example, non-wovens. Particularly advantageous results can be obtained by adding ethylene urea. Thus, e.g. by the addition according to the invention of ethylene urea

the retention of free formaldehyde in N-methylol group-containing crosslinkable aqueous plastic dispersions, reduces to the detection limit of usual determination methods for formaldehyde and is also maintained during the respective subsequent storage time of

this reduced level. The same applies to the films and coatings produced from the aforementioned dispersions according to the invention,

before or after their temperature treatment, whereby a practically formaldehyde-free finishing of fluorescent substances of any type is made possible by using an aqueous one-pot system.

Although the below co-used amounts according to the invention

polymerized films made of ethylene urea or

-coatings have somewhat higher hydrophilicity compared to films and coatings produced without a urea addition, are not adversely affected e.g. the dry and especially the wet workability and films and coatings produced by the dispersion according to the invention, surprisingly not negatively.

For the detection of formaldehyde, there are a number of determination methods whose results in their absolute assessment cannot generally be compared to each other. A demonstrative

method which is currently the safest for free formaldehyde in aqueous dispersions/ can be considered the "lutidine method". According to this method, formaldehyde is converted with acetylacetone in the presence of ammonia to 3,5-diacetyl-1,4-dihydrolutidine. The intensity of the resulting yellow color is measured

in spectrophotometer. The method is characterized by high sensitivity and little disturbance tendency.

Assessment of the films was carried out after storage of

the samples in connection with no. 2 of BGA recommendation XVIII

for melamine resin pressing compounds in the 9th announcement from the BGA of 1.8.1978 on "health-related assessment of plastics within the framework of the Food Act". Deviating from these previously given determination methods, the films were stored under stricter conditions in distilled water at 40°C for 4 hours.

A summary of the results with different plastic dispersion systems according to the lutidine method and assessment in connection with BGA recommendation XVIII is shown in table 1.

Table 2 shows the wet tearability of a special paper finished with a cross-linkable polymer dispersion depending on the addition of ethylene urea, as the values after temperature treatment at 150°C are of particular importance, since at 100°C activation energy to full

permanent cross-linking of polymers containing methylol groups is not yet available to the necessary extent.

The crosslinkable aqueous polymer dispersions according to the compound can be used for physiologically harmless bonding, wetting, strengthening or coating of materials of various types such as e.g. flat solid bodies, foils, granules, powders, fibres, threads, woven fabrics, non-wovens, paper. The application is preferably carried out by physiologically harmless fixing of non-wovens of natural, synthetic or mineral fibers or threads or their mixtures for the technical area, as well as for the sanitary, household and hygiene flora sectors

fabrics, further of paper.

Claims (9)

1. Formaldehyde-free aqueous plastic dispersion based on a crosslinkable polymer of ethylenically unsaturated monomers with a content of N-methylolamide and/or N-methyloletheramide groups, characterized in that the dispersion in holds a compound of formula I, where n = 0 or 1, X = oxygen, -CH2-, -CH(R)- or -N(R)-, where R means (C1-C4)-alkyl or (C1-C4)-alkylol, and R<1>, R<2> = H or OH. 2. Plastic dispersion according to claim 1, characterized in that it contains organic acids and/or organic acid emitters and has a solids content of from 15 to 65% by weight, referred to the aqueous dispersion. 3. Plastic dispersion according to claim 1 or 2, characterized in that it contains 0.15 to 6% by weight, referred to the aqueous dispersion, of a compound of formula I. 4. Plastic dispersion according to claim 1, 2 or 3, characterized in that it contains a compound of formula I, 1 2 where n = o and R , R =H. 5. Plastic dispersion according to claims 1 to 4, characterized in that the crosslinkable polymer contains N-methylol-acrylamide units. 6. Process for producing formaldehyde-free aqueous plastic dispersions based on a crosslinkable polymer of ethylenically unsaturated monomers with a content of N-methylolamide and/or N-methyloletheramide groups according to claims 1 to 6, characterized in that aqueous crosslinkable and N -methylolamide- and/or N-methyloletheramide group-containing polymer dispersions are mixed with a compound of formula I. 7. Process according to claim 6, characterized in that the compound of formula I is added as an alcoholic solution. 8. Use of polymer dispersions according to claims 1 to 5 for bonding, impregnation, reinforcement and coating of materials of different kinds. 9. Application of polymer dispersions according to claims 1 to 5 for fixing non-wovens of natural, synthetic or mineral fibers or their mixtures for technical areas as well as for the sectors of sanitary, household and hygiene fabrics, further for fixing paper, of woven and natural , synthetic or mineral fibers or their mixtures and for gluing foils of natural or synthetic materials.