EP0019169A1 - Use of an aqueous dispersion of an emulsion copolymer that contains amide groups for bonding nonwovens - Google Patents

Abstract

The amide group-containing copolymer contains recurring units of the general formula I <IMAGE> in which R represents H and / or CH3. When used, the preparations release virtually no formaldehyde. They are advantageously suitable as binders for the consolidation of nonwovens.

Description

This invention relates to binding agents, impregnating agents and coating agents based on aqueous dispersions of copolymers containing amide groups, which give crosslinking films, impregnating agents and coatings.

Binding, impregnating and coating agents based on aqueous dispersions of copolymers are increasingly being used, in particular in the field of producing bonded nonwovens from natural and / or synthetic, organic or inorganic fibers and also pigment prints, and in the fields of textile impregnation and coating which crosslink after drying and, if necessary, a heat treatment and are then largely resistant to the usual methods of chemical cleaning and washing. For example, in the case of chemical cleaning processes and washing processes, solidified nonwovens must neither lose their bulk, nor harden, nor become lappy and soft. Discoloration should not occur, for example, in the case of impregnation or coatings, or in the case of consolidated nonwovens. The known binders, impregnating agents and coating agents based on aqueous copolymers containing amide groups often contain as main monomers in amounts of 80 or more percent, ie as main monomers, mixtures of butadiene and styrene or acrylonitrile and very often acrylic and / or methacrylic acid esters 1 to 3 C. -Atoms containing alkanols and / or vinyl esters, for example of vinyl acetate, and / or vinyl chloride, optionally copolymerized together with acrylonitrile and butadiene. As amide group-containing monomers, such copolymers generally contain the N-methylolamides of acrylic and / or methacrylic acid and / or their ether poly-derived from alkanols usually containing 1 to 4 carbon atoms merized. In practice, the amount of such amide group-containing monomers is usually between 3 and 6% by weight and, in addition, the copolymers usually also contain 3 to 5 C atoms containing α, β-monoolefinically unsaturated mono- and / or dicarboxylic acids or their amides copolymerized. Examples of such binders are known from US Pat. No. 3,137,589.

When they are used after evaporation of the water, these known binders, impregnating agents and coating agents form films, coatings or impregnating agents as well as bonds between the fibers of nonwovens, which, when tempered at temperatures of generally 120 to 200, usually 130 to 160 ° C crosslink and thereby obtain excellent solvent and wash resistance. This also applies if such binders are used in pigment printing pastes. When tempering nonwoven fabrics that are solidified with such binders, or also when tempering coatings and impregnations produced in this way, considerable amounts of formaldehyde are generally released, which can lead to nuisance for those involved in the manufacture of the goods in question. Even when using bonded nonwovens at room temperature, formaldehyde is often released, which can lead to skin irritation. There has therefore been a need for a long time for corresponding binding agents, impregnating agents and coating agents, which also give washable and cleaning-resistant products when used, but no or only a lot less formaldehyde is released during their processing and use.

aufweisen. Die Copolymerisate der Binde-, Imprägnier- und überzugsmittel enthalten zu mindestens 85 % ihres Gewichts, d.h. als Hauptmonomere, (a) ein Gemisch aus 40 bis 60 Gewichtsteilen Styrol und/oder Acrylnitril und 60 bis 40 Gewichtsteilen Butadien oder (b) Acryl- und/oder Methacrylsäureester 1 bis 8 C-Atome enthaltender Alkanole und/oder Vinylester der Essig- oder Propionsäure und/oder Vinylchlorid und gegebenenfalls bis 40 Gew.% der gesamten Monomeren (b), an Acrylnitril, Styrol oder Butadien sowie zusätzlich zu den Monomeren (a) und (b) 0 bis 5 % ihres Gewichts an α,β-monoolefinisch ungesättigten, 3 bis 5 C-Atome aufweisenden Mono- und/oder Dicarbonsäuren und/oder deren Amide einpolymerisiert. Sie können in an sich üblicher Weise durch Emulsionspolymerisation der Monomeren hergestellt sein. Sie liegen in den Binde-, Imprägnier- und Überzugsmitteln in Form ihrer wäßrigen Dispersionen vor, die im allgemeinen einen Gehalt an derartigen Copolymerisaten von 30 bis 65, vorzugsweise von 40 bis 55 Gew.%, bezogen auf das Binde-, Imprägnier- und überzugsmittel haben. Die in den Copolymerisaten enthaltenden wiederkehrenden Einheiten der allgemeinen Formel I leiten sich von der N-Acrylamidoglykolsäure und/oder der N-Methacrylamidoglykolsäure ab, die bei der Herstellung der wäßrigen Copolymerisatdispersionen durch Emulsionspolymerisation eingesetzt werden kann, wobei ihre Menge bei der Emulsions-Copolymerisation im allgemeinen 3 bis 10 Gew.%, bezogen auf die gesamten Monomeren, vorzugsweise 3 bis 6 Gew.%, betragen kann. Acrylamidoglykolsäure und Methacrylamidoglykolsäure und ein Verfahren zu ihrer Herstellung sind aus der GB-PS 1 103 916 bekannt. (Aus dieser Patentschrift ist es auch bekannt, diese Monomere der Emulsionscopolymerisation zu unterwerfen und aus Copolymeren jener Monomerer Folien mit verringertem Quellvermögen in Trichloräthylen herzustellen.)This object is achieved by binding, impregnating and coating agents according to claim 1. The binding agents, impregnating agents and coating agents according to claim 1 preferably contain those copolymers which contain 3 to 10% by weight of units of the general formula 1

exhibit. The copolymers of binders, impregnants and coating compositions contain at least 85% of their weight, ie as main monomers, (a) a mixture of 40 to 60 parts by weight of styrene and / or acrylonitrile and 60 to 40 parts by weight of butadiene or (b) acrylic and / or methacrylic acid esters containing alkanols and / or vinyl esters of acetic or propionic acid and / or vinyl chloride and 1 to 8 carbon atoms and optionally up to 40% by weight of the total monomers (b), of acrylonitrile, styrene or butadiene and in addition to the monomers ( a) and (b) 0 to 5% of their weight of α, β-monoolefinically unsaturated mono- and / or dicarboxylic acids and / or their amides having 3 to 5 carbon atoms. They can be produced in a conventional manner by emulsion polymerization of the monomers. They are present in the binding agents, impregnating agents and coating agents in the form of their aqueous dispersions, which generally contain copolymers of this type 30 to 65, preferably from 40 to 55 wt.%, Based on the binder, impregnating and coating agent. The recurring units of the general formula I contained in the copolymers are derived from N-acrylamidoglycolic acid and / or N-methacrylamidoglycolic acid, which can be used in the preparation of the aqueous copolymer dispersions by emulsion polymerization, their amount generally being used in emulsion copolymerization 3 to 10% by weight, based on the total monomers, preferably 3 to 6% by weight. Acrylamidoglycolic acid and methacrylamidoglycolic acid and a process for their preparation are known from GB-PS 1 103 916. (From this patent it is also known to subject these monomers to emulsion copolymerization and to produce films with reduced swelling capacity in trichlorethylene from copolymers of those monomers.)

The recurring units of the general formula I can also advantageously be obtained in the amide group-containing copolymers by emulsion copolymers which contain the above-mentioned main monomers in copolymerized form in the amounts indicated therein, and which generally comprise 1.5 to 6% of their weight of acrylamide and / or contain copolymerized methacrylamide, reacted with glyoxylic acid, it being possible, for example, based on the copolymerized (meth) acrylamide, to use equivalent or excess amounts of glyoxylic acid; a deficit of glyoxylic acid can also be used. Furthermore, the amide group-containing copolymers which contain recurring units of the general formula I can be prepared by polymerizing the monomer mixture containing acrylic and / or methacrylamide in aqueous emulsion in the presence of glyoxylic acid under otherwise customary conditions.

In addition to the above monomers, the amide-containing copolymers present in the novel binder in the ^p rägnier- and coating compositions can also contain 0 to 3, preferably from 0.5 α to 1% of its weight of N-methylolamides, ß-nonoolefinisch unsaturated, 3 to Containing 5 carbon atoms containing mono- and / or dicarboxylic acids or their 1 to 4 carbon atoms in the alkyl radical containing copolymerized copolymer, in which case the copolymers contain from 3 to 6% of their weight of units of the general formula I. A particularly advantageous crosslinking is observed in those binders, impregnating agents and coating compositions whose copolymers containing amide groups, in addition to units of the general formula I, also have N-methylolacrylamide units and / or N-methylolmethacrylamide units, since this achieves a synergistic effect. which, when used solely as a binder for nonwovens, leads to particularly high resistance to washing and dry cleaning.

Alkanols containing 1 to 8 carbon atoms as acrylic and methyl acrylate esters in the production include, in particular, ethyl acrylate and methacrylate, n-butyl acrylate and methacrylate, isobutyl acrylate and methacrylate and 2-ethylhexyl acrylate and methacrylate as well as methyl acrylate and in quantities up to 10% by weight, based on the total monomers (b), methyl methacrylate and tert-butyl acrylate and methacrylate in question. The aqueous dispersions of the copolymers containing amide groups can be prepared in a conventional manner by emulsion polymerization using the customary radical-forming polymerization initiators, emulsifying and dispersing auxiliaries and, if appropriate, regulators. The amount of mostly anionic and / or nonionic emulsifiers is generally between 0.1 and 10, preferably between -1 and 5% by weight and examples of anionic emulsifiers are 6 to 18 carbon atoms Fatty acids, resin acids, from 4 to 18 carbon atoms containing fatty i alcohol sulfates, 10 to 18 carbon atoms Alkylsulfona- containing _"te, 10 to 18 carbon atoms-containing alkyl aryl, 4 to 18 carbon atoms containing hydroxyalkyl sulphonates, alkali metal and ammonium salts the sulfosuccinic acid ester and sulfonated adducts of ethylene oxide with fatty alcohols, fatty amides and fatty acids as well as with alkylphenols The emulsifiers are not critical for the agents according to the invention or the preparation of the dispersions, the usual amounts of emulsifiers for this can be used in the usual amounts Emulsifiers are adducts of ethylene oxide with fatty alcohols, such as lauryl, myristile, cetyl, stearyl and oleyl alcohol, with fatty acids, such as lauric, myristic, palmitic, stearic and oleic acid, and with their amides and with alkylphenol, such as Iso-octyl-, iso-nonyl- and dodecylphenol are mentioned, and examples of reaction products of ethylene oxide with I so-nonyl, dodecyl, tetradecyl mercaptan and higher alkyl mercaptans or higher alkyl thiophenols or corresponding reaction products of etherified or esterified polyhydroxy compounds with a longer alkyl chain, such as sorbitol monostearate. The alkoxylation products mentioned generally contain 5 to 80 mol of ethylene oxide, and those alkoxylation products of the type mentioned which contain propylene oxide in addition to ethylene oxide are also suitable.

Suitable initiators are, for example, inorganic peroxo compounds, such as hydrogen peroxide, sodium, potassium or ammonium peroxydisulfate, peroxocarbonates and borate peroxyhydrates, and also organic peroxo compounds, such as acyl hydroperoxides, diacyl peroxides, alkyl hydroperoxides, dialkyl peroxides and esters, such as tert-butyl perbenzoate. The amount of initiator is generally in the range from 0.01 to 5% by weight, based on the total monomers. The above Peroxo compounds can also be used in combination with reducing agents as redox catalysts. Examples of suitable reducing agents are alkali disulfites, alkali or ammonium hydrogen sulfites, thiosulfate, dithionite and formaldehyde sulfoxylates, furthermore iron (II) sulfate, titanium (III) sulfate, glucose and ascorbic acid. When using redox catalysts, the use of promoters is often advantageous. Traces of metal salts, in particular copper, manganese, iron, cobalt and / or nickel salts, may be mentioned as such.

Examples of suitable regulators are carbon tetrachloride, trichloromomethane, carbon tetrachloride, methallyl chloride, alcohols such as isopropanol and dodecanol, alkyl mercaptans and dialkyl xanthates, such as diisopropyl xanthate disulfide. The emulsion polymerization is generally carried out at from 10 to ₉₅ ° C., preferably from 40 to 90 ° C., the pH generally being between 1 and 9. This gives dispersions whose copolymer content is generally 30 to 60% by weight.

In the preparation process for the aqueous dispersions of the amide group-containing copolymers which contain units of the general formula I, emulsion copolymerization, which can be carried out, for example, by the monomer feed process or emulsion feed process, can be used instead of N-acrylamidoglycolic acid or N-methacrylamidoglycolic acid acrylamide , Acrylic or methacrylamide in a sufficient amount, ie generally in amounts of 1.5 to 6, preferably from 1.5 to 3.5,% by weight, based on the total monomers, and glyoxylic acid in a stoichiometric amount, based on acrylic - or methacrylamide, in the aqueous phase or further depending on the inflow of the monomers together with the monomers or separately according to the polymerization Feed polymerization mixture gradually. In this case, preference is given to using persulfates of the type mentioned above as polymerization initiators at temperatures from 60 to 85, in particular 70 to 85 ° C.

The binding agents, impregnating agents and coating agents according to the invention can, in addition to the aqueous dispersions of the amide group-containing copolymers which have repeating units of the general formula I, also conventional additives, e.g. Pigments, antioxidants, dyes, plasticizers and film-forming aids are contained in the usual quantities. They are particularly suitable as binders for nonwovens made from the usual natural and synthetic fibers, e.g. from cotton, wool, polyethylene glycol terephthalate, polyamides and / or polyolefins, as well as from rock wool, asbestos fibers etc. They are also suitable for impregnating woven and non-woven flat textile structures, as binders for textile printing pastes, paper coating slips and as coating agents, for example for foils, textile fabrics and objects made of metal.

When the agents are used as binders for non-woven fabrics, doubled, reinforced with thread, needled, rolled and / or shrunk nonwovens can be used. The binders can be applied to the nonwovens in a conventional manner, by impregnation, foam impregnation, spraying, splashing or printing. After treating the nonwovens with the binders according to the invention and removing excess binders, for example by squeezing, the impregnated nonwoven is generally dried and then tempered. Drying can take place, for example, in the course of 1 to 10 minutes at 100 to 170 ° C, the annealing within 0.5 to 3 minutes at temperatures of 110 to 200 ° C. One generally applies also binders in such an amount that the content of the consolidated nonwoven copolymer is 15 to 60% by weight, based on the amount of the fiber material.

The parts and percentages given in the following examples relate to the weight.

(A) Manufacturing Examples: example 1

An emulsion of 566 parts of ethyl acrylate, 5.5 parts of N-methylolacrylamide, 27 parts of N _- methacrylamidoglycolic acid and 6 parts of sodium dodecyl sulfate in 382 parts of water and 50 parts of a solution of 856 ° C. are added to a solution of 0.3 parts of potassium peroxydisulfate in 389 parts of water 4% potassium peroxydisulfate solution was gradually added over 2 hours while stirring. 25 parts of a 4% potassium peroxysulfate solution are then added at the same temperature over the course of 1 hour, and the mixture is then stirred at 85 ° C. for 2 hours. After cooling to 40 ° C., 0.4 part of cumene hydroperoxide and 0.4 part of sodium formaldehyde sulfoxylate are added and the mixture is stirred at this temperature for 1 hour. An aqueous dispersion of a copolymer containing amide groups with 4.5% by weight of repeating units of the general formula I is obtained. The dispersion can be used as such as a binder for nonwoven fabrics, and also as an impregnating agent for textiles and as a binder for pigment printing pastes.

Example 2

To a solution of 8 parts of a 30% aqueous solution of hydrogen peroxide, 0.24 parts of ascorbic acid and 0.0012 parts of iron (III) sulfate in 602 parts of water a solution of 1126 parts of ethyl acrylate, 26 parts of acrylamide and a solution of 34 parts of glyoxylic acid monohydrate, 26 parts of N-methylolmethacrylamide, 12 parts of sodium dodecyl sulfate and 200 parts of water, and 100 parts of an activator solution of 2.4 parts at 40 ° C. Ascorbic acid and 0.012 parts of iron (II) sulfate in 97.6 parts of water within 2 hours with stirring. Then another 20 parts of the activator solution of the composition mentioned are added at the same temperature within a further hour. After cooling, an aqueous dispersion of a copolymer containing amide groups is obtained which contains 4.5% by weight of units of the general formula I and which is suitable as such as a binder for nonwoven fabrics and also for the production of optionally pigmented coatings on flat textile webs.

Example 3

An emulsion of 284 parts of ethyl acrylate, 284 is added to a mixture of 4 parts of a 30% aqueous solution of hydrogen peroxide, 0.12 part of ascorbic acid and 0.0006 part of iron (II) sulfate in 425 parts of water at 45 ° C. Parts of n-butyl acrylate, 23 parts of N-methylolmethaerylamide (used as a 45% aqueous solution), 13 parts of acrylamide and 6 parts of sodium dodecyl sulfate in 401 parts of water and 50 parts of an aqueous activator solution composed of 1.2 parts of ascorbic acid and 0.0006 parts of iron (II) sulfate in 48.8 parts of water within 2 hours. Subsequently, 10 parts of further activator solution of the stated composition are added at the same temperature within a further hour. After cooling, 17 parts of glyoxylic acid monohydrate are added and an aqueous dispersion of a copolymer containing amide groups is obtained which contains 4.4% by weight of units of the general formula I. The dispersion is suitable as such and also after addition usual additives as binders for nonwovens, for example in the production of interlining.

Example 4

The procedure is as given in Example 1, but only 566 g of ethyl acrylate and 27 g of N-acrylamidoglycolic acid are used as monomers. An aqueous dispersion which can be used as such as a binder for nonwoven fabrics is obtained under otherwise identical conditions.

(B) Examples of the use of the dispersions prepared according to Examples 1 to 4 as binders for nonwoven fabrics: Example 5

A cross-laid nonwoven fabric (basis weight 40 g / m ² ) consisting of 65 parts of polyamide staple fibers (3.3 dtex / 60 mm staple length) and 35 parts of polyester staple fibers (1.7 dtex / 40 mm staple length) is Impregnation process impregnated with the binders of Examples 1-4. The solids content of the liquors is 15%.

1% of maleic acid (solid based on plastic solid) is added to the batches as a crosslinking catalyst. The substrates squeezed off after the impregnation are dried and condensed for 6 minutes at 150 ^° C. The squeezing pressure of the paddle is selected so that the fiber / binder ratio after drying is 2: 1.

• Die mit den Polymerisaten 1, 2 und 3 gebundenen Substrate überstehen den Chemisch-Reinigungsprozeß ohne erkennbare oberflächliche Schädigung. Der mit dem Binder 4 verfestigte Vliesstoff zeigt nur leichtes Ausfasern.

The finished nonwovens are subjected to a dry cleaning test in perchlorethylene. (DIN 54 303, part 1). The evaluation of the results leads to the following assessment:

• The substrates bound with the polymers 1, 2 and 3 survive the chemical cleaning process without visible surface damage. The nonwoven bonded with the binder 4 shows only slight fraying.

Example 6

A nonwoven fabric consisting of 100% polyamide fibers (3.3 dtex / 40 mn stack length) with a basis weight of ₄₅ g / m ² is impregnated with the binders of Examples 1-4 (batches as under Example 1), the Excess binder squeezed between 2 rollers and the impregnated substrate dried and condensed at 140 ° C for 6 minutes. The fiber / binder ratio is 2: 1 in all cases. The results of the strip tensile test (DIN 53 857, sheet 2) are summarized in Table 1 below:

Table 1

Strip tensile test

Example 7

A cross-laid carded nonwoven, consisting of 100% viscose fibers with 1.7 dtex titer and 40 mm stack length, which has a basis weight of 50 g / m ² , is made in the same way as in Examples 5 and 6 with the polymer dispersions 1 - 4 solidified. The results of the strip tensile tests of the nonwovens with a fiber / binder ratio of 7: 3 are summarized in Table 2 below.

Table 2

Strip tensile test

(C) comparative experiments Comparative Dispersion I

According to the information in Example 1, a mixture of 566 TEI _l s of ethyl acrylate, 13 parts of polymerized N-methylol methacrylamide (40% aqueous solution) and 13 parts of acrylic acid.

Comparative dispersion II

According to the information in Example 1, a monomer mixture of 566 parts of ethyl acrylate and 45.5 parts of N-methylolmethacrylamide is (45% _`aqueous solution) under otherwise identical conditions polymerized.

• Im Chemisch-Reinigungstest (Beispiel 5) übersteht das mit Dispersion II gebundene Substrat ohne erkennbare oberflächliche Schädigung, das mit Dispersion I verfestige Vlies zerfällt völlig.

Comparative dispersions I and II are subjected to the test conditions given in Examples 5 to 7 and the following results are obtained:

• In the chemical cleaning test (example 5), the substrate bound with dispersion II survives without any visible surface damage, and the nonwoven that solidifies with dispersion I completely disintegrates.

In the tensile test on strips (Example 6) to a polyamide non-woven fabric is used for dispersion I a maximum tensile force (F _H), total solids _k s of 700daN obtained for dispersion II of 720daN and the maximum tensile force (F _Hw), water wet for dispersion I with 190daN for dispersion II determined with 260daN.

In the strip tensile test (Example 7) on viscose nonwoven, the values listed in Table 3 below were obtained for dispersions I and II:

Table 3

Patrol test
(daN / 5 cm strip)

Claims (6)

1. Binding, impregnating and coating agents based on an aqueous dispersion of a copolymer containing amide groups, characterized in that the copolymer containing amide groups contains recurring units of the general formula I

contains, in which R represents H and / or CH ₃ . 2. Composition according to claim 1, characterized in that the amide group-containing copolymer has 3 to 10% by weight of the units of the general formula I. 3. Composition according to claim 1, characterized in that the amide group-containing copolymer 3 to 6 wt.% Units of general formula I and additionally 0.5 to 1.5 wt.% Units of general formula II

contains, in which R ^{1 is} H or CH ₃ and R ^{4 is} H or an alkyl radical containing 1 to 4 carbon atoms. 4. Composition according to claims 1 to 3, characterized in that the copolymers containing amide groups at least 85% of their weight ' (a) a mixture of 40 to 60 parts by weight of styrene and / or acrylonitrile and 60 to 40 parts by weight of butadiene or (b) Acrylic and / or methacrylic acid esters of alkanols and / or vinyl esters of acetic or propionic acid and / or vinyl chloride containing 1 to 8 carbon atoms and optionally additionally up to 40% by weight of the total monomers (b) of acrylonitrile, styrene or butadiene ,
and 0 to 5% by weight of α, β-monoolefinically unsaturated mono- and / or dicarboxylic acids and / or their amides containing 3 to 5 carbon atoms and / or their amides. 5. A process for the preparation of agents according to claims 1 to 4, characterized in that acrylic and / or methacrylamide copolymerized emulsions containing copolymers are reacted in aqueous dispersion with glyoxylic acid. 6. Use of the agent according to claim 4 for strengthening nonwoven fabrics.