Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/12—Polymerisation in non-solvents
  • C08F2/16—Aqueous medium
  • C08F2/22—Emulsion polymerisation
  • C08F2/24—Emulsion polymerisation with the aid of emulsifying agents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F218/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
  • C08F218/02—Esters of monocarboxylic acids
  • C08F218/04—Vinyl esters
  • C08F218/08—Vinyl acetate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J131/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid, or of a haloformic acid; Adhesives based on derivatives of such polymers
  • C09J131/02—Homopolymers or copolymers of esters of monocarboxylic acids
  • C09J131/04—Homopolymers or copolymers of vinyl acetate
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/64—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/02—Ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F218/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
  • C08F218/02—Esters of monocarboxylic acids
  • C08F218/04—Vinyl esters
  • C08F218/10—Vinyl esters of monocarboxylic acids containing three or more carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/04—Acids; Metal salts or ammonium salts thereof
  • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/12—Esters of monohydric alcohols or phenols
  • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
  • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
  • C08F220/1804—C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/52—Amides or imides
  • C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
  • C08F220/58—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide containing oxygen in addition to the carbonamido oxygen, e.g. N-methylolacrylamide, N-(meth)acryloylmorpholine
  • C08F220/585—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide containing oxygen in addition to the carbonamido oxygen, e.g. N-methylolacrylamide, N-(meth)acryloylmorpholine and containing other heteroatoms, e.g. 2-acrylamido-2-methylpropane sulfonic acid [AMPS]
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F228/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a bond to sulfur or by a heterocyclic ring containing sulfur
  • C08F228/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a bond to sulfur or by a heterocyclic ring containing sulfur by a bond to sulfur

Definitions

• the present invention relates to processes for the preparation of aqueous dispersions of vinyl ester-ethylene-acrylic acid amide
• Copolymers by means of free-radically initiated emulsion polymerization, the aqueous dispersions thus obtainable and their use, for example as binders or adhesives, in particular for the fiber bonding of nonwovens.
• Aqueous dispersions of emulsion polymers based on ethylenically unsaturated monomers have been used for some time for the consolidation of fibers for the production of nonwovens.
• monomers in this case (meth) acrylic acid esters, styrene, olefins or vinyl esters are very common.
• Copolymerization of so-called post-crosslinking monomers imparts cross-linking properties to the emulsion polymers, so that the emulsion polymers crosslink with each other and optionally also with the fibers and thus nonwovens with higher strength can be produced.
• N-methylolacrylamide (NMA) has prevailed in industrial practice predominantly.
• US 4449978 teaches copolymerizing from 1.75 to 3.5% by weight of N-methylolacrylamide and for the preparation of polymer dispersions having sufficient crosslinking properties and stabilities which make bonded nonwoven fabrics with acceptable dry and wet strengths accessible 1.25 to 8.25 wt .-% of acrylamide, based on the total amount of the monomers.
• polymers containing N-methylolacrylamide units can lead to a considerable introduction of formaldehyde into the
• formaldehyde can in this case come from the commercially available N-methylolacrylamide batches themselves. Thus, some 48% aqueous N-methylolacrylamide solutions contain 2% formaldehyde, as known, for example, from US 4449978. Furthermore, formaldehyde is liberated in the course of crosslinking of the N-methylol groups.
• Other sources of formaldehyde may be initiators or initiator systems used for the emulsion polymerization, such as this common sodium formaldehydesulfoxylate (SFS) or Formopon.
• US 5540987 or US 6787594 recommends the use of hydrophobic peroxide such as t-butyl hydroperoxide (tBHP) in combination with ascorbic acid or sulfinic acid derivatives, also known as Brueggolit® FF6.
• tBHP t-butyl hydroperoxide
• ascorbic acid or sulfinic acid derivatives also known as Brueggolit® FF6.
• hydrophobic peroxides it is difficult to control the particle sizes of vinyl ester copolymers, and very coarse and sedimentation-prone particle fractions are formed.
• DE19631935 in addition to N-methylolacrylamide and N-alkoxymethylacrylamides known, such as N- (isobutoxymethyl) acrylamide (IBMA) or N- (n-butoxymethyl) acrylamide (NBMA).
• IBMA isobutoxymethyl acrylamide
• NBMA N- (n-butoxymethyl) acrylamide
• DE19631935 and DE4432945 describe emulsion polymerization processes in which the initially introduced non-postcrosslinking monomers are completely polymerized before the metered addition of the acrylamide derivatives and the remaining monomers is recorded. The same applies to a process described in EP0731207.
• DE4240731 describes the preparation of copolymers using from 0.1 to 5.0% by weight of N-alkylolamides and N-alkoxyalkylamides, these postcrosslinking monomers being added only after at least 50% of the non-postcrosslinking comonomers have already been added were metered.
• DE 4240731 shows only that the original was fully polymerized at the aforementioned time and the metered monomers were polymerized continuously during their metering.
• EP 1777241 describes by way of example copolymers of vinyl esters, N-methylolacrylamide and other monomers, which were prepared in the absence of protective colloids and in the presence of small amounts of emulsifiers by emulsion polymerization, wherein individual monomers were distributed in a certain manner on initial and dosage.
• the polymer dispersions thus obtained have a content of free formaldehyde of significantly more than 30 ppm and lead to bonded nonwovens with over 20 ppm of free formaldehyde.
• EP0451554 the preparation of a binder for nonwoven fabrics is described by first the total amount of vinyl acetate is introduced and simultaneously with the beginning of the dosage the initiator to the start of the polymerization and N-methylol etheramide and other monomers were added.
• DE 3727181 recommends the complete or partial replacement of N-methylolamides or N-methylol-etheramides by vinylalkoxysilanes in order to reduce the formaldehyde content.
• the polymers described there are not sufficiently stable in storage, so that their crosslinking action decreases rapidly.
• No. 2005239362 teaches the use of binders based on vinyl acetate, vinyl versatate and postcrosslinking monomers, such as N-methylolacrylamide, as well as pre-crosslinking, polyunsaturated monomers, such as triallyl cyanurate, for improving the wet and dry strength of nonwovens.
• EP2138548 recommends polymers of vinyl acetate, vinylsatates and (meth) acrylamide derivatives, which have been prepared by emulsion polymerization in the presence of fully saponified polyvinyl alcohols. Regarding the beginning of the metering of the monomers during the emulsion polymerization, EP2138548 teaches that this should take place only after polymerizing at least 50% of the monomers initially charged. To reduce the formaldehyde content, there have been numerous attempts in the past to replace acrylamide derivatives with a wide variety of alternative postcrosslinking monomers, as for example in US Pat. Nos.
• the strength of bonded nonwoven fabrics is known to be dependent on a variety of factors, such as the type of fiber material, the method of forming the nonwoven fabric, the properties of the polymer binder, the amount of binder application, the method of binder application on the nonwoven fabric and the drying conditions of with the aqueous polymer dispersion applied nonwoven fabric, such as drying temperature, drying time and optionally the flow conditions. Accordingly, a comparison of numerical values for strength values of bonded nonwoven fabrics is only reasonably possible if in each case identical conditions under variation of an influencing variable, for example the properties of the polymer dispersion, are used.
• bonded nonwovens dry strength, wet strength (strength of the water-moist nonwoven), solvent strengths (strengths of the solvent-moist nonwoven), hydrophilicity, such as, for example, Drop-in time of a defined drop of water, absorption rate and absorption capacity.
• the object was to produce aqueous dispersions of vinyl ester-ethylene-acrylic acid amide copolymers by means of emulsion polymerization, which
• Values for the "capacity" of preferably at least 0.5, more preferably at least 0.7 and even more preferably at least 0.9 g are to be achieved; Particle size distributions with a modal value "x-mode" of the volume distribution density function of the particle diameter (most common particle size of the volume distribution density function) with values in the range of in particular 140 to 600 nm, preferably 150 to 500 nm and more preferably 150 to 400 nm and simultaneously provide a volume fraction of particles in particular greater than 900 nm, dF3 ( ⁇ 900 nm), in particular of ⁇ 30% by volume, preferably of ⁇ 25% by volume;
• a small coarse particulate fraction having particle sizes of greater than 40 ⁇ known as sieve residue or "grit ⁇ 40 ⁇ ", in particular special not more than 200 ppm, based on the weight of the dispersion;
• the invention relates to processes for the preparation of vinyl ter-ethylene-acrylamide copolymers in the form of aqueous dispersions by free-radically initiated emulsion polymerization of
• one or more monomers (a) and monomer (b) in whole or in part, and optionally monomer (c1) are initially introduced in water and
• Another object of the invention are the products obtainable by the aforementioned method.
• the invention also relates to uses of the aforementioned process products for bonding nonwoven fabrics, as adhesives, as an additive for adhesives or as an additive for coating agents.
• the point in time at which at least 50% by weight of the total monomers (c) are metered in according to the metering criterion according to the invention is also referred to below as the metering time t-DB in accordance with the invention.
• the dosing time t-DB which is essential to the invention is the time at which at least 50% by weight of the total monomers (c2) and (c3) are metered in according to the inventive dosing criterion.
• conversion of the monomers is familiar to the person skilled in the art and is defined as the quotient of the weight of the polymers formed up to the respective time point, that is to say the polymerized monomer proportions, and the weight of the total monomers introduced into the reactor up to this point in time % and is also referred to below as current turnover (sales UiA), also known under the term “instantaneous conversion”.
• sales UiA also known under the term “instantaneous conversion”.
• sales or current sales or sales UiA always refers to the aforementioned definition of sales.
• vinyl esters (a) are vinyl acetate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate or vinyl versatate, in particular vinyl esters of branched monocarboxylic acids having 9 to 11 carbon atoms, for example those disclosed in US Pat Trade names VeoVa® 10 VeoVa® 9 known compounds. Particularly preferred are vinyl acetate, vinyl versatate and vinyl laurate. Particularly preferred vinyl esters (a) used are 80 to 100% by weight of vinyl acetate, based on the total weight of the total vinyl ester (a) used.
• the acrylamide (cl) is also known under the name 2-propenamide.
• N-methylolmethacrylamide and in particular N-methylolacrylamide are preferred.
• aqueous mixtures Preference is given to the use of monomer (c2), in particular N-methylol acrylamide, in the form of aqueous mixtures with the monomer (c1), where the monomers (c1) and (c2) are present in a molar ratio of 2: 1 to 1: 2, in particular 1: 1.
• Such aqueous mixtures have a content of monomer (c1) and monomers (c2) of preferably from 30 to 60% by weight, more preferably from 40 to 55% by weight, and most preferably about 48% by weight, based on the total weight of the aqueous mixtures.
• Such aqueous mixtures with a molar ratio of about 1: 1 to monomers (c1) and (c2) are also known under the name "NMA-LF" or "MAMD".
• As monomers (c3) are N- (isobutoxymethyl) acrylamide (IBMA), N- (isobutoxymethyl) methacrylamide (IBMMA), N- (n-butoxymethyl) acrylamide (NBMA) or N- (n-butoxymethyl) methacrylamide (NBMMA ) prefers. Particularly preferred are N- (isobutoxymethyl) acrylamide (IBMA) or N- (n-butoxymethyl) acrylamide (NBMA).
• the monomers (d) are preferably vinyltrialkoxy- or alkylvinyldialkoxysilanes with branched or unbranched alkyl or alkoxy radicals having 1 to 4 C atoms.
• the alkyl radical the methyl radical is preferred.
• Preferred alkoxy radicals are methoxy, ethoxy, methoxyethylene, ethoxyethylene, methoxypropylene glycol ether, ethoxypropylene glycol ether radicals.
• Preferred examples are vinyltrimethoxysilane or vinyltriethoxysilane.
• the ethylenically unsaturated monomers (e) are preferably selected from the group (el) comprising acrylic acid esters and methacrylic acid esters of alcohols having 1 to 10 carbon atoms, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n Butyl methacrylate, 2-ethylhexyl acrylate; ethylenically unsaturated dicarboxylic esters such as diisopropyl fumarate; Hydroxyalkyl (meth) acrylates such as hydroxypropyl acrylate o- hydroxyethyl acrylate and polyethylenically unsaturated monomers such as divinyl adipate, diallyl maleate, allyl methacrylate, butanediol diacrylate or triallyl cyanurate.
• ethylenically unsaturated monomers (e) can be selected from the group (e2) comprising ethylenically unsaturated carboxylic acids having 1 to 10 C atoms, such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid; and ethylenically unsaturated sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid or vinylsulfonic acid.
• Particularly preferred monomers (e2) are vinyl sulfonate or its alkali metal salts, acrylic acid or 2-acrylamido-2-methylpropanesulfonic acid (AMPS).
• the total amounts of the monomers (c2) and (c3), based on the total weight of the monomers (a) to (e), are from 0.23 to 0.90% by weight, preferably 0.28 to 0.85 wt .-% and particularly preferably 0.35 to 0.85 wt .-%.
• Comonomer mixtures suitable for emulsion polymerization include, for example
• monomer (c2) preferably N-methylolacrylamide, 0 to 0.67% by weight, in particular 0.40 to 0.67% by weight of monomer (c3), preferably N - (isobutoxymethyl) acrylamide (IBMA) or N- (n-butoxymethyl) acrylamide (NBMA);
• monomer (c2) preferably N-methylolacrylamide.
• aqueous dispersions of vinyl ester-ethylene-acrylic acid amide copolymers obtainable therewith are preferably adjusted to a pH of 6.
• comonomer mixtures comprising
• aqueous dispersions of vinyl ester-ethylene-acrylic acid amide copolymers obtainable therewith are preferably adjusted to a pH of 6.
• the monomers (c2) are preferably used in the form of "NMA-LF".
• the proportions of "NMA-LF” are preferably from 0.5 to 1.0% by weight, based on the total weight of the monomers (a) to ( e).
• the comonomer mixture still contain 0.6 to 15 wt .-%, more preferably 0.6 to 7 wt .-% and most preferably 1.0 to 5.5 wt .-% of monomers (e ), based on the total weight of the comonomer mixture (a) to (e).
• monomers (e) e
• Particularly preferred are 0.3 to 10% by weight, more preferably 0.3 to 3.5% by weight, most preferably 0.5 to 2.7% by weight of the monomers (el). , in particular butyl acrylate and hydroxyethyl acrylate; such as
• the monomers (e2) in particular acrylic acid and vinylsulfonate.
• the percentages relating to the comonomer mixtures are in each case based on the total weight of the particular comonomer mixture from the monomers (a), (b), (c), and optionally (d) and optionally (e) and each supplement to 100% by weight.
• the process according to the invention for the preparation of the copolymers by means of free-radical emulsion polymerization can be carried out in the customary polymerization reactors in the copolymerization of gaseous monomers, such as ethylene, in customary pressure reactors.
• the total vinyl ester (a) used and at least part of the total ethylene (b) used are initially charged.
• the template will generally contain part of the total water used.
• acrylamide (cl) Preferably, from 15 to 50% by weight of the total amount of acrylamide (cl) used is initially charged. It is also preferable to provide at least 0.8% by weight, particularly preferably 0.8 to 1.5% by weight, of acrylamide (c1), based on the total weight of monomers (a) to (e). Of course it is also possible not to submit acrylamide (cl).
• no monomer (c2) and / or no monomer (c3) and / or no monomer (d) is presented.
• the monomers (e) can be completely or partially charged or metered.
• ethylenically unsaturated sulfonic acids in particular vinyl sulfonate
• / or (meth) acrylic acid esters in particular butyl acrylate
• hydroxyalkyl (meth) acrylates in particular hydroxyethyl acrylate
• / or ethylenically unsaturated carboxylic acids in particular acrylic acid
• the template is free of emulsifiers.
• the original is heated, for example with stirring to temperatures of 30 ° C to 80 ° C, preferably 40 ° C to 70 ° C and more preferably from 45 ° C to 65 ° C.
• the pressure in the reactor, in which the is located is preferably 10 bar to 100 bar.
• the pressure is known to depend on the reactor volume, its degree of filling, ie in particular on the amounts of water, monomers, in particular of the monomers (a) and (b), and on the temperature.
• the ethylene pressure set at the start of the emulsion polymerization can be kept constant over the entire reaction time, preferably over the entire metering time of the monomers (a), for example by metering in ethylene. However, it is also possible not to supplement the initially introduced into the reactor amount of ethylene or to vary the ethylene pressure during the polymerization within said limits.
• the emulsion polymerization is carried out with initiation by means of conventional free-radical initiators, which are preferably used in amounts of from 0.05 to 3.0% by weight. Percent, based on the total weight of monomers (a) to (e).
• the free-radical formers can be activated either directly by increasing the temperature or preferably, even at low temperatures, by redox reaction.
• a radical generator the usual oxidation and reducing agents can be used. It is advantageous to add a common activator such as iron ammonium sulfate to the reactor before starting the emulsion polymerization.
• oxidizing and reducing agents preferably takes place by continuous metering of aqueous solutions of oxidizing agent (initiator feed 1) and reducing agent (initiator feed 2).
• Initiator dosing 1 and initiator dosing 2 are generally spatially separated, but metered in parallel.
• As a reducing agent ascorbic acid, sodium isascorbate or sulfinic acid derivatives, also known under the trade name Brueggolit® FF6, are preferred.
• persulfate compounds are preferable, and ammonium persulfate is particularly preferable; However, it may also be advantageous to use alkali persulfate, in particular sodium persulfate, especially if ammonium ions are to be completely excluded. This can be advantageous if discoloration problems occur and should be minimized; then the combined use of sodium persulfate or potassium persulfate with Brüggolit® FF6 is recommended.
• the free-radical formers used are preferably not formaldehyde sulfoxylates or formopon.
• time t-RB The point in time at which the heating of the polymerization batch is recognizable.
• the heating of the polymerization batch is considered, for example, as recognizable when the polymerization mixture is heated to 0.1 ° C to 1 ° C.
• the increase in temperature depends, as is known, on the respective reactor volume, its degree of filling and the respective cooling conditions.
• the heating of the polymerization batch as a result of the exothermic nature of the incipient polymerization reaction is also evident from the fact that the temperature control switches over to cooling.
• the pressure in the reactor for example, increased by 0.1 to 0.5 bar.
• the conversion of the monomers initially charged or, if appropriate, previously metered in is known to be very low.
• the actual conversion of the monomers at any given time, based on the total weight of the monomers (a) to (e) used up to this point in time, is also referred to as the conversion UiA.
• the conversion of the monomers UiA at the time t-RB 0 to ⁇ 2 wt .-%, preferably 1 to 2 wt .-%, each based on the total weight of the monomers used at the time t-RB (a) to (e ).
• the remaining monomers i. the monomers (a) to (e) not used in the initial charge are metered in after initiation of the emulsion polymerization, wherein the metering criterion according to the invention must be observed. Accordingly, starting from the dosing time t-DB essential to the invention, the following monomers are preferably metered in independently of one another in the following amounts:
• preferably 90 to 100 wt .-%, particularly preferably 100 wt .-% of the total monomers used (c3) are added; preferably 95 to 100 wt .-%, particularly preferably 100 wt .-% of the total monomers used (d) is added.
• novel metered additions of the monomers (c1), (c2), optionally (c3) and / or optionally (d) may be carried out spatially separated or preferably spatially in common, one after the other or preferably simultaneously or in parallel. In this case, the dosing criterion according to the invention is to be observed.
• Any remaining monomers (a), (b) and optionally (e) not used in the initial charge are also metered in.
• fractions of the monomers (a) to (e) can also be added after initiation of the emulsion polymerization but before the dosing time essential to the invention, t-DB, with the premise that the dosing criterion according to the invention is adhered to.
• the actual conversion of the monomers (a) to (e) initially introduced or metered in at this time into the metering time instant t-DB is 8 to 50% by weight, preferably 9 to 45% by weight. , particularly preferably 10 to 40 wt .-% and most preferably 10 to 35 wt .-% is.
• the data in% by weight relate here to the weight of the monomers (a) to (e) introduced or metered in up to the dosing instant in time t-DB essential to the invention.
• the current conversion of the monomers initially charged and / or metered in consisting of vinyl ester (a), amides (c), optionally alkoxysilanes (d) and optionally monomers (e), preferably 13 to 50 Wt .-%, particularly preferably 18 to 45 wt .-% and most preferably 20 to 40 wt .-%, based on the sum of the inventions
• the actual conversion of the vinyl acetate initially charged and / or metered in is preferably from 13 to 50% by weight, more preferably from 18 to 45% by weight and most preferably from 20 to 40% by weight.
• essential dosing time t-DB submitted and / or dosed vinyl acetate is preferably from 13 to 50% by weight, more preferably from 18 to 45% by weight and most preferably from 20 to 40% by weight.
• the actual conversion of the ethylene (b) initially charged and optionally metered in is preferably 6 and 35% by weight, more preferably 7 to 30% by weight and most preferably 8 to 30% by weight. -%, Based on the weight of up to the invention essential dosing time t-DB submitted and optionally dosed ethylene (b).
• the dispersants used may be the ionic or nonionic emulsifiers customarily used in the emulsion polymerization.
• the method according to the invention therefore also permits the at least substantial omission of emulsifiers.
• the emulsifiers can be distributed on template and dosage.
• the template contains no emulsifier.
• the emulsion polymerization is preferably initiated in the absence of emulsifiers. Any emulsifiers are therefore preferably added after the metering time t-DB essential to the invention.
• Suitable emulsifiers are, for example, anionic surfactants, such as alkyl sulfates having a chain length of 8 to 18 carbon atoms, alkyl and alkylaryl ether sulfates having 8 to 18 carbon atoms in the hydrophobic radical and up to 40 ethylene or propylene oxide units, alkyl or alkyl Rylsulfonate with 8 to 18 carbon atoms, ⁇ lklaresulfonate, esters and half esters of sulfosuccinic acid with monohydric alcohols or alkylphenols.
• anionic surfactants such as alkyl sulfates having a chain length of 8 to 18 carbon atoms, alkyl and alkylaryl ether sulfates having 8 to 18 carbon atoms in the hydrophobic radical and up to 40 ethylene or propylene oxide units, alkyl or alkyl Rylsulfonate with 8 to 18 carbon atoms, ⁇ lklaresulfon
• Suitable nonionic surfactants are, for example, alkyl polyglycol ethers or alkylaryl polyglycol ethers having 8 to 40 ethylene oxide units.
• alkyl ether sulfates or dodecylbenzenesulfonates is preferred.
• the emulsion polymerization according to the invention is carried out in the absence of protective colloids.
• protective colloids in the context of emulsion polymerizations is well known to the person skilled in the art and generally comprises water-soluble polymers, in particular polyvinyl alcohols, preferably vinyl alcohol / vinyl acetate copolymers containing from 80 to 100 mol% of vinyl alcohol units; Polyvinylpyrrolidone or hydroxyethylcelluloses.
• Dispensing with protective colloids serves the purpose of producing emulsion polymers having the desired particle size distributions.
• protective colloids can increase product viscosity and reduce the water resistance of bonded nonwoven fabrics, and can also be a source of thermal yellowing of bonded nonwoven fabrics.
• Vinyl esters (a) are added, for example, as metering 3 to the reactor.
• the monomers (c1) and optionally (c2) are added, for example, in an aqueous dosage 4, which is preferred.
• the optional monomers (c3) and (d) are preferably added to the dosage 3.
• Monomers (c3) can also be added within the dosage 4, whereas it is preferred to dose monomers (d) within the dosage 3, or part of the dosage 3.
• the optional monomers (e) are added, for example, to dosages 3 or 4. It may be advantageous to introduce water-soluble monomers (e) into the dosage 4.
• Emulsifier is preferably added to the dosage 4.
• dosing 3 containing vinyl ester (a) and optionally monomers (c3) and / or (d) and optionally some of the monomers (e), as well as a metering, are added almost instantaneously or slightly in time to the dosing time t-DB essential to the invention 4, containing monomers (c1) and (c2), but optionally preferably a portion of any monomers (e) and residual emulsifier, started and dosed at a constant rate over a period of 1 to 6 hours, preferably in 2 to 4 hours ,
• Unincorporated monomer (b) is added to the reaction system within this time period, preferably ending before dosing 3 is terminated, for example at substantially constant pressure or at a constant flow rate as dosing 5.
• the initiator doses 1 and 2 are added so that at the end of doses 3 and 4 at least a conversion of all previously used monomers from 60 to 95 wt .-%, preferably from 70 to 90 % By weight is reached.
• Dosages 3 and 4 are preferably stopped simultaneously.
• the initiator doses 1 and 2 are generally further added until the conversion of the monomers (a) to (e) used is preferably> 95% by weight, preferably> 98% by weight. has reached. It can be beneficial for that be to increase the dosing rates of the initiator doses 1 and 2 and / or their concentrations.
• any unreacted monomer levels after initiator doses 1 and 2 have ended it may be expedient to further reduce the residual monomer content, for example by postpolymerization using customary redox components such as t-butyl hydroperoxide as the oxidant.
• Reduction of residual monomer levels while minimizing levels of volatile organic compounds is possible by conventional stripping with steam.
• the addition of 5 to 20 grams, preferably 8 to 12 grams of a 10% aqueous hydrogen peroxide solution per kilogram of a 50% dispersion has been found.
• Such addition prior to conventional steam stripping minimizes significant tendencies of possible product yellowing, particularly when ascorbic acid is used as the reducing agent.
• the preferred pH range for the emulsion polymerization reaction is 2 to 6.
• pH values during the emulsion polymerization reaction of ⁇ 4.5 and in particular of ⁇ 3 are preferred.
• the pH during the polymerization is controlled by suitably adjusting the pH values of the reactor charge and aqueous dosages, such as, in particular, Dosage 4.
• the pH of the dispersion obtained is usually adjusted to values between 4 and 5.
• the pH of the resulting dispersion is adjusted to preferably 6, more preferably 6 to 7, otherwise the positive crosslinking effect caused by the monomers (d) will decrease within a few weeks.
• the pH adjustment or control of the pH can with acids such as sulfuric acid, formic acid, acetic acid; or with bases such as ammonia, caustic soda, potassium hydroxide, amines; or by using buffer substances, such as alkali metal acetate, alkali metal carbonate, alkali metal diphosphates.
• the glass transition temperature Tg of the copolymers according to the invention is generally -20 ° C to + 20 ° C, preferably -15 ° C to + 10 ° C.
• the choice of the monomers (a) to (e) for achieving such glass transition temperatures Tg is familiar to the person skilled in the art.
• the dispersions prepared by the process according to the invention generally have a solids content of from 35 to 65% by weight, preferably from 40 to 60% by weight and in particular from 45 to 55% by weight.
• the Brookfield viscosity of the dispersions is preferably 50 to 2000 raPas, particularly preferably 100 to 1500 mPas (determined using a Brookfield viscometer at 23 ° C. at 20 rpm at a solids content of the dispersions of 49 to 51% by weight).
• the polymers have a volume fraction of particles with dF3 900 nm) of preferably ⁇ 30 vol .-%, particularly preferably ⁇ 25 vol. % and at the same time particle size distributions with a modal value of the volume density distribution function x-mode of preferably 140 to 600 nm, more preferably 150 to 500 nm and most preferably 150 and 400 nm (determination as described below under point 1.4).
• the coarse particulate fraction of the polymers having particle sizes greater than 40 ⁇ m, also known as sieve residue or "grit” is preferably 200 200 ppm, based on the weight of the dispersion (determination as described below under point 1.5).
• the free formaldehyde content of the dispersions having a solids content of 45 to 55% is preferably 30 30 ppm and more preferably ⁇ 25 ppm (determination as described below under 1.6).
• the free formaldehyde content for bonded nonwoven fabrics is preferably 10 10 ppm, more preferably ⁇ 7.5 ppm, and most preferably ⁇ 5 ppm (determined as described below under 2.3).
• the amounts of the monomers (c1) or (c2) according to the invention are undershot, the minimum requirements for nonwoven strengths to be achieved can no longer be met.
• the requirements with respect to the limits to be observed for the free formaldehyde content of the dispersions of in particular ⁇ 30 ppm, preferably ⁇ 25 ppm and for the free formal dehydgehalt bonded nonwovens sufficient strength of in particular ⁇ 10 ppm, preferably ⁇ 7.5 ppm and more preferably of ⁇ 5 ppm no longer complied with.
• any monomers (d) used are preferably added in the amounts according to the invention and preferably in the manner according to the invention according to the dosing criterion according to the invention.
• any monomers (d) used are preferably added in the manner according to the invention according to the dosing criterion according to the invention.
• the vinyl ester-ethylene-acrylic acid amide copolymers prepared according to the invention surprisingly impart the desired strengths, in particular the desired wet and solvent strengths, to the level of commercially available styrene / acrylate dispersions, without the disadvantages of the latter with respect to insufficient hydrophilicity equipped nonwoven fabrics and preferably have free formaldehyde levels for the vinyl ester-ethylene-acrylic acid amide copolymer dispersions of ⁇ 30 ppm and for the finished nonwoven fabrics of ⁇ 10 ppm, especially of ⁇ 5 ppm.
• the vinyl ester-ethylene-acrylamide copolymers prepared by the process according to the invention are therefore particularly suitable for the production of "ultra-low-formaldehyde" nonwovens
• the vinyl ester-ethylene-acrylamide copolymers according to the invention can also be used in the production or surface refinement of papers for bonding cellulosic materials Ria, such as paper and paperboard, in formulations for aqueous paints, for impregnation and coating of textile fabrics, for example in the carpet backing, are used.
• the following examples serve to illustrate the invention in detail and should not be construed as limiting the invention in any way.
• the respective conversion of the monomers at the respective time ti during the emulsion polymerization reaction was calculated from the solids content FGi of a representative process sample taken from the reactor at time ti.
• the solids content FGi of each representative process sample was determined by the rapid method described in Section 1.1.
• a process sample taken from the reactor at time ti had the same composition as the reactor contents at time ti, with the only difference that the respective process sample does not contain ethylene, and thus is a representative process sample and thus contains representative proportions, for example, of unreacted monomers , except ethylene, as well as polymerized monomer proportions.
• feedstock combines monomers, auxiliaries and water.
• auxiliaries combines monomers, auxiliaries and water.
• sales calculation the following parameters are introduced:
• - ti stands for any time during the emulsion polymerization, for example, for the invention dsierzeittician t-DB; t "stands for any time at which all feedstocks have been added to the reactor.
• MMon the total weight of monomers Mon
• MMoniti the total weight of all monomers Mon, which were initially introduced into the reactor and / or metered in at time ti.
• Moni is the sum of all monomers except ethylene; the total weight of monomers Moni is called MMonl; MMonl (ti) is the total weight of all monomers Moni, which were initially introduced into the reactor and / or added up to the time ti. Monomers Moni are thus all monomers (a) and (c) to (e) subsumed.
• Mon2 is ethylene; the total weight of monomers Mon2 is called MMonl; MMon2 (ti) is the total weight of all ethylene monomers which have been introduced and / or added to the reactor up to time ti.
• - W stands for water; the total weight of water W is called MW; MW ⁇ ti) is the total weight of water that was introduced into the reactor and / or metered in until the time ti.
• auxiliaries stands for auxiliaries; the total weight of the excipients H is called MH; MH ⁇ ti) is the total weight of all auxiliaries, which were initially introduced into the reactor and / or added up to time ti.
• UiMonl stands for the instantaneous conversion of the monomers Moni and is the weight ratio of the total weight of monomers Moni polymerized up to the time ti and the total weight of all monomers MMon1 (introduced and / or added to the reactor up to time ti) ti).
• UiMon2 represents the instantaneous conversion of the ethylene Mon2 and is the weight ratio of the total weight of the monomer Mon2 polymerized up to the time ti and the total weight of the ethylene MMon2 introduced and / or metered into the reactor up to the time ti ti).
• UiA stands for the instantaneous vonversion of all monomers Mon and is the weight ratio of the total weight of monomers Mon polymerized up to time ti, that is the total weight of the mixed monomers formed up to time ti, and the total weight of the monomers up to Time ti in the Reakto] and / or metered monomers MMon (ti).
• the amounts of feedstocks at time ti in the reactor are easily determined from the amounts of the amounts charged in the reactor and the amounts added to the reactor until time ti.
• the viscosity of the dispersion was after tempering to 23 ° C with a Brookfield viscometer according to equipment specification, using spindle 2 or 3, depending on the viscosity range, at 20 rpm, measured. The viscosity is given in mPas.
• the dispersion was diluted sufficiently with water. From the plot of the volume distribution density function of the particle diameter f3 (x) one determines the position of the mode value of f3 (x) as the most frequent particle diameter (x-mode) in nanometers. From the plot of the volume distribution function of the particle diameter F3 (x), the volume fraction of particles greater than or equal to 900 nm is determined as dF3 900 nm) in volume%. Under the generally given assumption that the density of the particles is independent of their size, this volume fraction corresponds to the weight fraction. 1.5 sieve residue (grit> 40 pm)
• the residue of the dispersion given in parts per 10 6 characterizes coarse-grained fractions in the dispersion with dimensions greater than 40 ⁇ .
• 100 grams of the dispersion were diluted with one liter of distilled water, then poured through a 150 mesh nylon mesh, and the passage was filtered through a mesh of mesh size 40 ⁇ . It was because rinsed with water until the passage was clear.
• the residue on the sieve fabrics was weighed back after drying and the sieve residue per sieve fabric, based on dispersion, was calculated. In Table 3, the total residue on both screens was greater than 40 ⁇ indicated.
• the present polymer dispersions were diluted 1: 1 with water and transferred by ultracentrifugation (2 h at 32,000 rpm) in a clear as possible latex serum.
• the latex sera thus obtained were then determined photometrically according to ISO 15373 (Method A, Plastics - Polymer Dispersions - Determination of free formaldehyde).
• the binding capacity of the polymer dispersions described was characterized in a comparative manner on two different, cellulose-containing and nonwoven fabrics.
• Typical tissue paper (100% pulp, 26 gsm, dry strength: 3.7 N / 45 mm, wet strength: 0.9 N / 45 mm, with 2 ppm formaldehyde) was mixed with a liquor of the respective 30% polymer dispersion In the gap ("gusset") of a Mathis HVF Foulard (Mathis / CH) homogeneously impregnated and dried by means of a laboratory through-air dryer (Fleissner, 3 min / 150 ° C) and crosslinked The corresponding binder orders were gravimetrically after 24 h air conditioning in standard atmosphere (ISO 139, 2005, 23 ⁇ 2 ° C, 50 ⁇ 3%).
• a thermally pre-bonded airlaid web (75 gsm, 88% fluff pulp and 12% PP / PE bicomponent fibers, 0.85 mm thickness, dry strength 500 g / 5 cm, wet strength 300 g / 5 cm) became a 20% spray liquor sprayed homogeneously on both sides with a semi-automatic spray unit using the airless method (slot nozzles Unijet 8001 E, 5 bar) and then dried in a laboratory through-air dryer (Mathis LTF, Mathis / CH) at 160 ° C. for 3 min.
• 10 fleece strips (20 cm clamping length, 5 cm clamping length) were made in the transverse direction to the machine production direction and, as described in Chap. 2.1. a maximum tensile force measurement with a deformation rate of 150 mm / min. subjected.
• the formaldehyde content of the nonwovens bonded to the abovementioned polymer dispersions was determined according to ISO 14184-1 (textiles determination of the content of formaldehyde, Part 1: free and hydrolyzed formaldehyde (water extraction method, 1999) or according to WSP 310.2 (11) (Standard Test Method for Free and Hydrolysed Formaldehyde in Nonwovens (Water Extraction Method - Method 1, EDANA / INDA 2011).
• Tissue nonwoven drop single time (TEZ):
• the measurement of the droplet sinking time TEZ is used to evaluate the hydrophilicity or hydrophobicity of the filmed polymer on a film. serförmigen substrate (ability of wetting by water).
• the dripping time TEZ is measured as follows:
• Airlaid fleece Relative water absorption capacity:
• the amount of water absorbed in grams (g) corresponds to the water absorption capacity (hereinafter referred to as capacity) of the nonwoven fabric and is read in a mass (g) against time (s) application at 180s. 3.
• capacity water absorption capacity
• the reactor was evacuated, the vacuum was broken with nitrogen, and nitrogen was passed through the reactor for at least 5 minutes. Subsequently, the template monomer was added while stirring and after tempering to target temperature, the reaction by parallel metering of doses 1 and 2, or started only by means of dosing 1.
• the dispersion was cooled in a reactor under vacuum.
• VAE vinyl acetate-ethylene copolymerizations
• Comparative Examples V4 to V8 was a double-walled 2-liter pressure reactor from Büchi, for working pressures up to 85 bar, equipped with electronic temperature measurement and control, a three - stage paddle stirrer with variable speed, safety valve and dosing options for at least five dosing options for parallel dosing of two initiator components (dosage 1 for the oxidant, dosed from above, and dosing 2 for the reducing agent, dosed from below), monomer or monomer mixture (dosing 3 ) and an aqueous solution (dosage 4) containing, for example, emulsifier and water-soluble monomers, such as For example, acrylic acid, acrylamide and N-methylolacrylamide, as well as for ethylene (dosage 5, if used).
• the aqueous portion of the reactor receiver was adjusted to pH 4.0 by using 1% formic acid each and aspirated into the evacuated reactor. It was then evacuated again, the vacuum was broken with nitrogen, evacuated again and the monomer template was aspirated with stirring. Subsequently, the reactor was heated to nominal temperature of usually 50 ° C, set to target speed of usually and unless otherwise indicated 500 rpm and pressed during heating the desired amount of ethylene to mass. The setpoint temperature was kept substantially constant until it cooled.
• doses 3 and 4 were dosed uniformly over three hours each.
• the vinyl acetate-ethylene copolymerization for Comparative Example C9 was carried out in a 5-liter pressure reactor, for working pressures up to 100 bar, with analogous equipment as the 2-liter reactor.
• the vinyl acetate-ethylene copolymerization for Example 4 was carried out in a 600 liter pressure reactor, for working pressures up to 85 bar, with analogous equipment as the 2 liter reactor. raw materials
• a emulsifier A was a fatty alcohol ether-sulfate Na salt with 12 C atoms in the alkyl radical and 3 EO units (known, for example, as Genapol® ZRO or Disponil® FES27) as aqueous Solution with an active ingredient content of 27 + 1 wt .-% for use.
• NMA-LF N-methylolacrylamide
• Vinyl sulfate monomer was used as a 25 wt .-% aqueous solution of sodium vinylsulfonate.
• the vinyltriethoxysilane used was GENIOSIL® GF56 from WACKER Chemie AG.
• a styrene-acrylate standard dispersion with the following monomer composition in% by weight was prepared: 12.0% styrene; 71.3% butyl acrylate; 6.0% acrylamide; 6.4% methacrylic acid; 2.4% acrylic acid and 1.9% hydroxyethyl acrylate.
• the reactor feed consisted of 598 grams of water, 3.0 grams of Texapon K12 emulsifier and 67.3 grams of styrene.
• a monomer mixture 2 consisting of 467.5 grams of butyl acrylate, 52.8 grams of methacrylic acid, 19.95 grams of acrylic acid and 16 grams of hydroxyethyl acrylate at a rate of 208.6 g / hr.
• the ammonium persulfate dosage was still running for 40 minutes Auspolymerisationszeit.
• the temperature was maintained at 79 to 82 ° C.
• the polymerization mixture was cooled and adjusted with water to 40 wt .-% of solids content.
• a styrene-acrylate standard dispersion with the following monomer composition in% by weight was prepared: 12.4% of styrene; 74.0% butyl acrylate; 4.1% acrylamide; 6.6% methacrylic acid; 2.5% acrylic acid and 0.35% N-methylolacrylamide.
• the reactor template consisted of 598 grams of water, 6.1 grams of Texapon K12 emulsifier and 67.3 grams of styrene.
• a monomer mixture 2 consisting of 467.5 grams of butyl acrylate, 52.8 grams of methacrylic acid and 19.95 grams of acrylic acid at a rate of 202.6 g / hr.
• the ammonium persulfate dosage was still running for 40 minutes Auspolymerisationszeit.
• the temperature was maintained at 79 to 82 ° C. After completion of the polymerization, the polymerization was cooled.
• Comparative Example V4 A VAE dispersion having the following monomer composition in% by weight was prepared: 69.65% vinyl acetate, 23.00% ethylene, 2.93% VeoVa®10, 1.43% acrylic acid, 0.73% butyl acrylate, 0.59% vinyl sulfonate and 1.69% acrylamide.
• the reactor feed consisted of 490 grams of water, 3.5 grams of a 0.1% aqueous hydroquinone monomethyl ether (HQME) solution, 27.36 grams of a 30% aqueous acrylamide solution, 22.9 grams of a 25% aqueous vinyl sulfonate solution , 4 grams of a 1% ferro- ammonium sulfate (FAS) solution, 172.3 grams of vinyl acetate, 7.1 grams of butyl acrylate, 28.5 grams of VeoVa®10, and 224 grams of ethylene.
• HQME 0.1% aqueous hydroquinone monomethyl ether
• FAS ferro- ammonium sulfate
• a VAE dispersion having the following monomer composition in% by weight was prepared: 70.88% vinyl acetate, 22.54% ethylene, 2.10% acrylic acid, 1.01% butyl acrylate, 0.58% vinyl sulfonate and 2.90% acrylamide.
• the reactor feed consisted of 490 grams of water, 3.5 grams of a 0.1% aqueous hydroquinone monomethyl ether (HQME) solution, 27.40 grams of a 30% aqueous acrylamide solution, 22.9 grams of a 25% aqueous vinyl sulfonate solution , 4 grams of a 1% ferro- ammonium sulfate (FAS) solution, 200.0 grams of vinyl acetate, 10.0 grams of butyl acrylate, and 224 grams of ethylene.
• HQME 0.1% aqueous hydroquinone monomethyl ether
• FAS ferro- ammonium sulfate
• dosage 3 consisting of 506 grams of vinyl acetate
• dosage 4 consisting of 61.5 grams of water, 30.5 grams of a 28% aqueous emulsifier A, 3.5 grams 0, l% aqueous HQME solution, 68.5 grams of a 30% aqueous acrylamide solution, 20.9 grams of acrylic acid, adjusted to a pH of 3.9 with a 12.5% aqueous ammonia solution started , After completion of doses 3 and 4 was proceeded to general polymerization rule for the 2-liter reactor.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 69.30% vinyl acetate, 22.89% ethylene, 2.91% VeoVa®10, 1.42% acrylic acid, 0.73% butyl acrylate, 0.58% vinylsulfonate, 1.88% acrylamide and 0.29% N-methylolacrylamide.
• the reactor feed consisted of 490 grams of water, 3.5 grams of a 0.1% aqueous hydroquinone monomethyl ether (HQME) solution, 27.36 grams of a 30% aqueous acrylamide solution, 22.9 grams of a 25% aqueous vinyl sulfonate solution , 4 grams of a 1% ferro- ammonium sulfate (FAS) solution, 172.3 grams of vinyl acetate, 7.1 grams of butyl acrylate, 28.5 grams of VeoVa®10, and 224 grams of ethylene.
• HQME 0.1% aqueous hydroquinone monomethyl ether
• FAS ferro- ammonium sulfate
• a VAE dispersion having the following monomer composition in% by weight was prepared: 69.12% of vinyl acetate, 22.83% of ethylene, 2.90% of VeoVa®10, 1.42% of acrylic acid, 0.72% of butyl acrylate, 0.58% vinylsulfonate, 1.99% acrylamide and 0.44% N-methylolacrylamide.
• the reactor template was identical to Example 1.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 68.95% vinyl acetate, 22.77% ethylene, 2.90% VeoVa®10, 1.41% acrylic acid, 0.72% butyl acrylate, 0.58% vinylsulfonate, 2.08% acrylamide and 0.59% N-methylolacrylamide.
• the reactor template was identical to Example 1.
• VAE dispersion was prepared with the same monomer composition as for Example 3.
• the reactor receiver consisted of 143.5 kg of water, 1.13 grams of hydroquinone monomethyl ether (HQME), 8.70 kg of a 30% aqueous acrylamide solution, 7.25 kg of a 25% aqueous vinyl sulfonate solution, 12 , 8 grams of ferro-ammonium sulfate (FAS), 54.5 kg of vinyl acetate, 2.25 kg of butyl acrylate, 9.0 kg of VeoVa®10 and 71 kg of ethylene.
• HQME hydroquinone monomethyl ether
• FAS ferro-ammonium sulfate
• dosages 1 and 2 proceeded at a rate of 4.6 kg / hr for an additional 60 minutes. Subsequently, 6.5 kg of a 10% aqueous solution of hydrogen peroxide were added in 10 minutes and then adjusted to a pH of about 4.5 by metering a 12.5% aqueous ammonia solution. The reactor contents were then emulsified with the addition of 60 grams of silicone defoamer in 5 kg of water in a flash vessel and defoamed there for one hour under vacuum.
• Example 4 was reproduced as indicated.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 67.82% vinyl acetate, 22.40% ethylene, 2.85% VeoVa®10, 1.39% acrylic acid, 0.71% butyl acrylate, 0.57% vinylsulfonate, 3.69% acrylamide and 0.58% N-methylolacrylamide.
• the reactor template was identical to Example 1.
• dosage 3 consisting of 506 grams of vinyl acetate
• dosage 4 consisting of 18.0 grams of water, 30.5 grams of a 28% aqueous emulsifier A, 3.5 grams 0, 1% aqueous HQME solution, 13.9 grams of acrylic acid, 95.48 grams of a 30% aqueous acrylamide solution and 12.01 grams of a
• a VAE dispersion was prepared with the same monomer composition as for Example 3.
• the reactor template was identical to Example 1.
• a dosage 3 consisting of 506 grams of vinyl acetate, parallel to a dosage 4A, consisting of 68.0 grams of water, 24.63 grams of a 26% aqueous emulsifier solution A, 2.63 grams of a 0.1% aqueous HQME solution, 10.43 grams of acrylic acid, 20.52 grams of a 30% aqueous acrylamide solution, total adjusted to a pH of 3.6 with a 12.5% aqueous ammonia solution , began. With the start of doses 3 and 4A, the rates of both initiator doses 1 and 2 were increased. Dosing 3 was dosed for 3 hours and Dose 4A was uniformly dosed for 135 minutes.
• Dosage 4B consisting of 2.2 grams of water, 8.2 grams of a 26% aqueous emulsifier solution A, 0.88 grams of a 0.1% aqueous HQME solution, 3.47 Grams of acrylic acid, 20.42 grams of a 30% aqueous acrylamide solution and 12.01 grams of a 48% aqueous N-methylolacrylamide solution, total with a 12.5% aqueous ammonia solution to a pH of 3 , 6, started and dosed evenly for 45 minutes and parallel to the dosage 3 and simultaneously stopped with dosage 3.
• a VAE dispersion with the same monomer composition as for Example 5 was prepared.
• the reactor template was identical to Example 1.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 67.66% vinyl acetate, 22.51% ethylene, 2.86% VeoVa®10, 1.40% acrylic acid, 0.71% butyl acrylate, 0.58% vinylsulfonate, 3.50% acrylamide, 0.29% N-methylolacrylamide and 0.49% N- (isobutoxymethyl) acrylamide (IBMA).
• the reactor template was identical to Examples 1.
• dosage 3 consisting of 501.1 grams of vinyl acetate and 4.9 grams of IBMA
• dosage 4 consisting of 23.0 grams of water, 30.5 grams of a 28% aqueous Emulsifier solution A, 3.5 grams of a 0.1% aqueous HQME solution, 13.9 grams of acrylic acid, 88.79 grams of a 30% aqueous acrylamide solution and 6.01 grams of a 48% aqueous N-methylolacrylamide solution, total adjusted to a pH of 3.6 with a 12.5% aqueous ammonia solution.
• a VAE dispersion with the following monomer composition in% by weight was prepared: 70.57% vinyl acetate, 22.39% ethylene, 2.09% acrylic acid, 1.00% butyl acrylate, 0.57% vinyl sulfonate, 3 08% acrylamide and 0.29% N-methylolacrylamide.
• the reactor template was identical to Comparative Example V5.
• dosage 3 consisting of 506.0 grams of vinyl acetate
• dosage 4 consisting of 51.1 grams of water, 30.5 grams of a 28% aqueous emulsifier solution A, 3.5 Grams of a 0.1% aqueous HQME solution, 20.4 grams of acrylic acid, 75.39 grams of a 30% aqueous acrylamide solution, and 6.09 grams of a 48% aqueous N-methylol acrylamide solution, totaling 12.5 % aqueous ammonia solution to a pH of 3.9, started.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 69.59% vinyl acetate, 22.40% ethylene, 2.09% acrylic acid, 1.00% butyl acrylate, 0.57% vinyl sulfonate, 3.08% Acrylamide, 0.28% N-methylolacrylamide and 1.00% vinyltriethoxysilane.
• the reactor template was identical to Example 7.
• dosage 3 consisting of 496.0 grams of vinyl acetate and 10 grams of vinyltriethoxysilane
• dosage 4 consisting of 51.5 grams of water, 30.5 grams of a 28% aqueous emulsifier A solution , 3.5 grams of a 0.1% aqueous HQME solution, 20.4 grams of acrylic acid, 75.12 grams of a 30% aqueous acrylamide solution. and 5.86 grams of a 48% aqueous N-methylolacrylamide solution, adjusted to a total pH of 3.9 with a 12.5% aqueous ammonia solution.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 69.09% of vinyl acetate, 22.40% of ethylene, 2.09% of acrylic acid, 1.00% of butyl acrylate, 0.57% of vinylsulfonate, 3 08% acrylamide, 0.28% N-methylolacrylamide, 1.00% vinyltriethoxysilane and 0.50% N- (isobutoxymethyl) acrylamide (IBMA).
• the reactor template was identical to Example 7.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 72.42% vinyl acetate, 17.80% ethylene, 2.85% VeoVa® 10, 1.39% acrylic acid, 0.71% butyl acrylate, 0, 57% vinyl sulfonate, 3.69% acrylamide and 0.58% N-methylolacrylamide.
• the reactor template was identical to Example 1, with the difference that only 178 grams of ethylene were used.
• dosage 3 consisting of 552.0 grams of vinyl acetate
• dosage 4 consisting of 18.0 grams of water, 30.5 grams of a 28% aqueous emulsifier A, 3.5 Grams of a 0.1% aqueous HQME solution, 13.9 grams of acrylic acid, 95.58 grams of a 30% aqueous acrylamide solution and 12.01 grams of a
• a VAE dispersion having the following monomer composition in% by weight was prepared: 73.08% vinyl acetate, 14.97% ethylene, 0.40% acrylic acid, 8.34% butyl acrylate, 0.08% vinyl sulfonate, 2, 15% acrylamide, 0.59% N-methylolacrylamide and 0.39% Lubrizol® 2403A (acrylamidopro- panesulfonate Na salt, AMPS).
• the reactor feed consisted of 523 grams of water, 3.2 grams of a 0.1% aqueous hydroquinone monomethyl ether (HQME) solution, 2.9 grams of a 25% aqueous vinyl sulfonate solution, 7.3 grams of a 5% aqueous emulsifier solution of aerosol ® A102, 11.4 grams of a 20% aqueous emulsifier solution of Genapol® PF40, 4 grams of a 1% Ferroammone Sulfate (FAS) solution, 66.0 grams of vinyl acetate, 7.7 grams of butyl acrylate, and 143 grams of ethylene.
• HQME hydroquinone monomethyl ether
• Example 12 A VAE dispersion having the following monomer composition in% by weight was prepared: 82.788% vinyl acetate, 12.05% ethylene, 0.56% acrylic acid, 0.76% butyl acrylate, 0.07% vinyl sulfonate, 3.20% Acrylamide and 0.59% N-methylolacrylamide.
• the reactor feed consisted of 555 grams of water, 3.7 grams of a 0.1% aqueous hydroquinone monomethyl ether (HQME) solution, 2.9 grams of a 25% aqueous vinyl sulfonate solution, 1.2 grams of a 30% aqueous emulsifier solution of aerosol ® A102, 2.3 grams of a 97% aqueous emulsifier solution of Genapol® PF40, 4 grams of a 1% Ferroammone Sulfate (FAS) solution, 65.0 grams of vinyl acetate, 7.6 grams of butyl acrylate and 121 grams of ethylene.
• HQME hydroquinone monomethyl ether
• dosage 3 consisting of 766 grams of vinyl acetate
• dosage 4 consisting of 30 grams of water, 62.7 grams of a 30% aqueous emulsifier Aerosol® MA, 3.7 grams 0, 1% aqueous HQME solution, 5.6 grams of acrylic acid, 106.96 grams of a 30% aqueous acrylamide solution and 12.25 grams of a 48% aqueous N-methylolacrylamide solution, total of 12.5% aqueous ammonia solution adjusted to a pH of 4.0, started.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 66.14% vinyl acetate, 28.71% ethylene, 0.74% acrylic acid, 0.67% butyl acrylate, 0.06% vinyl sulfonate, 3.10% Acrylamide and 0.59% N-methylolacrylamide.
• the reactor feed consisted of 525 grams of water, 3.5 grams of a 0.1% aqueous hydroquinone monomethyl ether (HQME) solution, 2.47 grams of a 25% aqueous vinyl sulfonate solution, 6.12 grams of a 5% aqueous emulsifier solution of aerosol ® A102, 9.39 grams of a 20% aqueous emulsifier solution of Genapol® PF40, 4 grams one 1% Ferroammonium Sulfate (FAS) solution, 55.0 grams of vinyl acetate, 6.5 grams of butyl acrylate, and 185 grams of ethylene.
• HQME hydroquinone monomethyl ether
• FAS Ferroammonium Sulfate
• a VAE dispersion having the following monomer composition in% by weight was prepared: 66.41% vinyl acetate, 28.83% ethylene, 0.74% acrylic acid, 0.67% butyl acrylate, 0.06% vinyl sulfonate, 3.11% Acrylamide and 0.17% N-methylolacrylamide.
• An ethylene dosage was identical to Example 13. After completion of doses 3 and 4 was proceeded to the general polymerization protocol for the 2-liter reactor. In each case 92 grams of dosage 1 and dosage 2 were consumed. The product was adjusted to a pH of 4.5 and a solids content of about 50% with 12.5% ammonia solution.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 68.37% vinyl acetate, 29.68% ethylene, 0.76% acrylic acid, 0.69% butyl acrylate, 0.07% vinyl sulfonate, 0, 12% acrylamide and 0.31% N-methylolacrylamide.
• Dose 3 Thirty minutes after the start of dosing of the initiator components, with the parallel dosage of Dose 3, identical to Example 13, and Dose 4, consisting of 50.0 grams of water, 78.5 grams of a 25% aqueous emulsifier solution Genapol® X360, 4.0 grams a 0.1% aqueous HQME solution, 7.2 grams of acrylic acid, 3.80 grams of a 30% aqueous acrylamide solution, and 6.0 grams of a 48% aqueous N-methylol acrylamide solution, totaling 12.5%.
• the aqueous ammonia solution is adjusted to a pH of 4.0.
• An ethylene dosage was identical to Example 13. After completion of doses 3 and 4 was proceeded to the general polymerization protocol for the 2-liter reactor.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 66.31% vinyl acetate, 21.90% ethylene, 2.79% VeoVa®10, 1.96% acrylic acid, 0.69% butyl acrylate, 0.56% vinylsulfonate, 3.28% acrylamide, 0.56% N-methylolacrylamide and 1.96% hydroxyethyl acrylate.
• the reactor template was identical to Example 1.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 68.87% vinyl acetate, 21.85% ethylene, 1.95% acrylic acid, 0.98% butyl acrylate, 0.56% vinyl sulfonate, 3.28% Acrylamide, 0.56% N-methylolacrylamide and 1.95% hydroxyethyl acrylate.
• the reactor template was identical to Example 7.
• a VAE dispersion having the following monomer composition in% by weight was prepared: 68.71% vinyl acetate, 21.96% ethylene, 1.96% acrylic acid, 0.98% butyl acrylate, 0.56% vinyl sulfonate, 3.10% Acrylamide, 0.29% N-methylolacrylamide, 1.96% hydroxyethyl acrylate and 0.49% N- (isobutoxymethyl) acrylamide (IBMA).
• the reactor template was identical to Example 7.
• a VAE dispersion with the following monomer composition in% by weight was prepared analogously to Example 5 of the specification DE4240731 A1: 75.02% vinyl acetate, 21.08% ethylene, 0.84% acrylic acid, 0.73% butyl acrylate, 0.07% Vinylsulfonate, 1.50% acrylamide and 0.75% N-methylolacrylamide.
• the reactor feed consisted of 500 grams of water, 2.43 grams of a 25% aqueous vinyl sulfonate solution, 1.01 grams of a 30% aqueous emulsifier solution of Aerosol® A102, 9.39 grams of a
• Dosage 1 consisted of 75 grams of a 10% aqueous ammonium persulfate solution; Dosage 2 consisted of 75 grams of a 5% aqueous sodium formaldehyde sulfoxylate solution (known as Bruegitolit®). Doses 1 and 2 were dosed uniformly over a total of 6 hours.
• VAE dispersion having the following monomer composition in% by weight was prepared: 80.78% vinyl acetate, 14.52% ethylene, 0.19% vinyl sulfonate, 4.01% acrylamide and 0.50 % N-methylolacrylamide.
• This comparative example is based essentially on the "Comparative Example 1" specified in US2005 / 0239362 A1, in which no vinyl versatate was used and most of the NMA-LF (MAMD) used there is replaced by mainly acrylamide and only one portion of N-methylolacrylamide of 0.5% by weight based on total monomer was used.
• MAMD NMA-LF
• the reactor receiver consisted of 1072 grams of water, 20 grams of a 25% aqueous vinylsulfonate solution, 20 grams of Rhodacal DS10 emulsifier solution, 100 grams of a 30% Aerosol® A102 aqueous emulsifier solution, 62.5 grams of a 10% aqueous solution of citric acid, 1.05 grams of Na citrate, 1.5 grams of a 10% aqueous solution of ferroammonium sulfate (FAS), 2086 grams of vinyl acetate and 375 grams of ethylene pressurized to 40 ° C at a stirrer speed of 800 rpm resulted in equilibrium pressure from 29.5 bar.
• FAS ferroammonium sulfate
• Dosage 1 consisted of a 2.5% aqueous solution of t-butyl hydroperoxide and Dosage 2 of a 5% aqueous solution of sodium isoascorbate.
• Dosing 2 10 grams were dosed quickly to feed the reactor and then dosing 1 started at a rate of 40 grams / hr. 25 minutes after the start of Dose 1, exotherm was registered, followed by Dose 4, consisting of 27 grams of a 48% aqueous solution of N-methylolacrylamide, 345 grams of a 30% aqueous solution of acrylamide, and 1 gram of a 1% aqueous solution of hydroquinone monomethyl ether (HQME) started at a rate of 160 grams / hr, the rate of Dosage 1 increased to 80 grams / hr and Dosage 2 also at the rate of 80 Grams / h were restarted.
• Dose 4 consisting of 27 grams of a 48% aqueous solution of N-methylolacrylamide, 345 grams of a 30% aqueous solution of acrylamide, and 1 gram of a 1% aqueous solution of hydroquinone monomethyl ether (HQME) started at a
• the setpoint temperature has now been increased evenly from 40 ° C to 60 ° C within 60 minutes.
• One hour after the start of dosage 4 its rate was reduced to 106.5 grams / hr and dosed for a further 2 hours.
• the rates of Doses 1 and 2 were increased to 120 grams / hr and both dosed for an additional 65 minutes.
• the product was adjusted to a pH of 4.5 and a solids content of 50% by weight.
• a vinyl acetate copolymer dispersion having the following monomer composition in% by weight was prepared: 76.72% vinyl acetate, 17.45% VeoVa® 10, 0.22% vinyl sulfonate, 0.56% butyl acrylate, 0 , 76% acrylic acid, 2.84% acrylamide and 1.64% vinyltriethoxysilane.
• the reactor receiver consisted of 351.5 grams of water, 2.5 grams of a 0.1% aqueous solution of hydroquinone monomethyl ether (HQME), 0.5 grams of a 27% aqueous solution of Emulsifier A, 8.0 grams of a 25% aqueous solution of vinyl sulfonate, 10 grams of a 30% aqueous solution of acrylamide, total of 1% aqueous solution of formic acid adjusted to pH 5.5, 60 grams of vinyl acetate and 5 grams of butyl acrylate.
• the reactor mixture was heated to 50 ° C and added from 43 ° C 3 grams of a 1% aqueous solution of ferroammonium sulfate (FAS). The stirrer speed was set at 150 rpm.
• Dosage 2 consisted of a 5% aqueous solution of ammonium persulfate and dosage 2 of a 1.7% aqueous solution of ascorbic acid.
• the doses 1 and 2 were started at 10 grams / h and now the external jacket temperature to 50 ° C found. 10 minutes after the start of dosages 1 and 2, dosage 3 containing 624 grams of vinyl acetate, 156 grams of VeoVa® 10 and 14.7 grams of vinyltriethoxysilane was started and metered evenly over a period of 244 minutes.
• Dose 4 containing 290 grams of water, 17.5 grams of a 27% aqueous solution of Emulsifier A, 17.5 grams of a 40% aqueous emulsifier solution of Genapol® X150, 6.8 grams of acrylic acid , 74.5 grams of a 30% aqueous solution of acrylamide, 2.5 grams of a 0.1% aqueous solution of hydroquinone monomethyl ether (HQME), total with a 12.5% aqueous solution of ammonia to a pH of 4.0, started and evenly dosed over a period of 231 minutes. With the start of dosage 3, the rates of doses 1 and 2 were increased to 15 grams / h and metered until 30 minutes after dosing of dosage 3.
• HQME hydroquinone monomethyl ether
• Table 1 gives essential recipe data; Table 2 contains for the vinyl acetate-ethylene copolymers, the conditions for the dosing start of a N-methylolacrylamide-containing dosage (usually a dosage 4); Table 3 lists essential analytical data for the aqueous polymer dispersions, and Table 4 sets forth the test results for tissue and airlaid nonwovens bonded with these dispersions.
• Table 1 Essential recipe data
• Table 2 Characteristic data for the dosing start DB of a N-methylol acrylamide-containing dosage (usually a dosage 4) for vinyl acetate-ethylene copolymerizations
• Nonwoven fabric in ppm based on the weight of the bonded nonwoven fabric
• Nonwoven fabric in ppm based on the weight of the bonded nonwoven fabric
• the different nonwoven strengths for the standard binder according to Comparative Example VI are used here for reference values for all examples and comparative examples and are each defined 100% for Comparative Example VI.
• the commercial product of Comparative Example C2 provided nonwoven strengths at the level of the standard binder VI, with strengths in the range of ⁇ 15%, ie 85% to 115% compared to VI found. Since the product VI is accepted commercially, strength values of at least 85% based on the strength values of the standard binder VI can be sufficiently defined.
• Comparative Examples VI to V3 A disadvantage for Comparative Examples VI to V3 is the clearly too low hydrophilicity of bonded nonwovens, which manifests itself in very high values for the drop inink time on tissue fleece and the clearly too low capacity for airlaid nonwoven. Accordingly, Comparative Examples VI to V3 do not meet the requirements for sufficient hydrophilicity of bonded nonwoven fabrics.
• VAE vinyl acetate-ethylene
• Example V6 which is based on Example 3, in contrast to Example 3, the NMA-containing dosage was only at a conversion of the monomers UiA of 84.7 wt .-%, based on the weight of the time of NMA dosing start started in the reactor introduced monomers.
• significantly lower wet strengths and solvent strengths of only 70 to 80% based on the strength values of the standard binder VI were achieved; these strength values are too low.
• Example C7 which is based on Example 5, unlike Example 5, the NMA-containing dosage (Dosage 4) very shortly after the start of the reaction t-RB, ie shortly after detection of exothermic reaction, ie when the jacket temperature of the reactor begins to decrease Initiation of the reaction was detected 17 minutes after dosing start of the initiator doses 1 and 2 and dosing start for dosing 4 was 20 minutes after initiator doses 1 and 2 had been started.
• Dosage 4 very shortly after the start of the reaction t-RB, ie shortly after detection of exothermic reaction, ie when the jacket temperature of the reactor begins to decrease Initiation of the reaction was detected 17 minutes after dosing start of the initiator doses 1 and 2 and dosing start for dosing 4 was 20 minutes after initiator doses 1 and 2 had been started.
• Binder for nonwovens is not suitable.
• Example 6 was based on Example 1, but an additional 0.49 wt .-% N- (isobutoxymethyl) acrylamide (IBMA) were used, whereby the wet strength and in particular the solvent resistance of bonded nonwoven fabrics were advantageously further increased.
• IBMA isobutoxymethyl
• Examples 7 to 10 were based on Comparative Example C5, but now each 0.29 wt .-% of N-methylolacrylamide were used and the dosing criterion of the invention was taken into account.
• all of the nonwoven strengths determined could be significantly increased compared to comparative example C5, essentially as a result of the low proportion of NMA, and met the requirements set.
• Example 8 starting from Example 7, additionally and advantageously 1.0% by weight of vinyltriethoxysilane was used, whereby in particular the solvent resistance of bonded nonwovens could be significantly increased.
• Example 9 The additional use of 0.50% by weight of N- (isobutoxymethyl) -acrylamide (IBMA) in Example 9, starting from Example 8, again leads to an increase in the nonwoven strength values, in particular the wet strengths being markedly increased and the solvent strengths being increased to a very high extent , Overall, the product according to Example 9 gave the bonded nonwovens overall significantly higher strengths than the standard binder according to VI.
• IBMA isobutoxymethyl
• Examples 6 to 9 are also characterized by a particularly low content of free formaldehyde for the bonded nonwoven fabrics of in each case 5 ppm.
• Example 10 was based on Example 1 except that a lower amount of ethylene, an increased amount of acrylamide and 0.58% by weight of N-methylolacrylamide were used.
• Example 10 showed clearly high nonwoven strengths above the level for the standard binder according to VI and, in addition, the required hydrophilicity of the bonded nonwovens at low levels of free formaldehyde required.
• the proportion of emulsifier used was ⁇ 1.0% by weight, based on the total amount of monomer used for the polymerization, the reaction template in each case containing no emulsifier.
• Examples 11 to 13 For examples 11 to 13, emulsifiers were used in a proportion of about 2.1 ⁇ 0.2% by weight, based on the total amount of monomers used for the polymerization, with 10 to 15% of the emulsifier fraction being introduced into the reactor master. Lower particle sizes were achieved. For these examples, the proportion of ethylene monomer was varied between about 15 and about 29 wt .-% based on the total monomer.
• nonwoven strength values achieved for these examples meet the minimum requirement of at least 85% of the strength values of the standard binder according to VI, with the solvent strengths in particular being dependent on the type of emulsifiers used and being correspondingly adjustable.
• the selectable fraction for the emulsifier fraction based on the total monomer these examples resulted in some of the clearly hydrophilic nonwovens.
• Comparative Example C8 demonstrates that when using only 0.17% by weight of N-methylolacrylamide, ie less than the NMA contents of 0.23 to 0.65% by weight, based on the total monomer, of the invention, the requirements for nonwoven strengths of at least 85% of the strengths of the standard binder according to VI can no longer be met.
• examples 14 to 16 in each case copious amounts of 3% by weight of acrylamide and in each case 1.96% by weight of acrylic acid and hydroxyethyl acrylate, in each case based on the total monomer, were used.
• Examples 14 and 15 were each 0.56 wt .-% of N-methylolacrylamide and for Example 16, 0.29% by weight of NMA and additionally 0.49% by weight of N- (isobutoxymethyl) acrylamide (IBMA) were used.
• the NMA-containing metering was started at a monomer conversion UiA of the monomers charged in the reactor in the range from 8 to 50% by weight, based on the weight of all monomers charged, and thus the metering criterion according to the invention was observed.
• Comparative Example V10 Comparative Example V10
• This comparative example corresponds to an example given in DE 4240731 A1 (example 5 there).
• This comparative example demonstrates that a late metering of N-methylolacrylamide initiated in DE 4240731 A1, in this case at a monomer conversion UiA of 81.2% by weight, based on the total weight of the catalyst, up to the time of commencement of NMA metering into the reactor added monomers, even when using 0.75 wt .-% of NMA, ie more NMA than the inventive proportions of 0.23 to 0.65 wt .-% of NMA based on total monomer, not to the required strength Accordingly, the inventive sales range (dosing criterion) UiA of 8 to 50% by weight is surprisingly decisive for the strength values to be achieved.
• the obtained nonwoven strength values do not reach the required level of at least 85% of the strength value of the standard binder according to VI.
• This comparative example relates to a vinyl acetate copolymerization for which no ethylene and no N-methylol-acrylamide was used. There were u.a. 2.84 wt .-% acrylamide and 1.64 wt .-% vinyltriethoxysilane used. At expected low values for the free formaldehyde content for the dispersion and the bonded nonwovens, nonwoven strengths are obtained at the level of the standard binder according to VI and in some cases significantly more. However, since the glass transition temperature of the resulting polymer is well above about 10 ° C, its application results in "hard" bonded nonwoven fabrics with insufficient flexibility.

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