EP1046737B1 - Method of manufacturing airlaid nonwoven fabrics - Google Patents

Method of manufacturing airlaid nonwoven fabrics Download PDF

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Publication number
EP1046737B1
EP1046737B1 EP00107105A EP00107105A EP1046737B1 EP 1046737 B1 EP1046737 B1 EP 1046737B1 EP 00107105 A EP00107105 A EP 00107105A EP 00107105 A EP00107105 A EP 00107105A EP 1046737 B1 EP1046737 B1 EP 1046737B1
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Prior art keywords
weight
powder
polymer
fibre
fiber
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EP00107105A
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German (de)
French (fr)
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EP1046737A1 (en
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Korad Alfons Dr. Wierer
Holger Dr. Poths
Richard Dr. Goetze
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Wacker Chemie AG
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Wacker Chemie AG
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Classifications

    • 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
    • D04H1/587—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 characterised by the bonding agents used
    • 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
    • D04H1/42—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 characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/425—Cellulose series
    • 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
    • D04H1/60—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 dry state, e.g. thermo-activatable agents in solid or molten state, and heat being applied subsequently

Definitions

  • the invention relates to a method for producing nonwoven fabrics after the airlaid process, with fibers and powder Binding agents are placed in the air flow, and with it available nonwovens and their use.
  • WO-A 96/39553 describes the prior art for production air-laid nonwovens using the airlaid process, which are used for example in hygiene products, Find household items or in filter media.
  • This will be natural Fibers, for example cellulose fibers (fluff pulp), inflated to a wire band with air, the air drawn off and the flat fiber structure thus obtained with an aqueous binder or thermoplastic fibers, under the influence of heat, Pressure and / or water jets, solidified.
  • the WO-A 96/39553 itself relates to the manufacture of nonwovens the airlaid process, with an aqueous polymer dispersion for fiber binding is used and the penetration depth of the latex binder into the laid out fiber structure by the spray pressure or the vacuum applied is controlled.
  • a disadvantage of the airlaids which are only bound with aqueous binders is the lack of binding of the nonwoven at high basis weights, so that delamination of the nonwoven layers inside can occur.
  • the reason for this is that in the case of thick nonwovens, the polymer portion of the binder dispersion does not go through and only water penetrates into the interior of the fiber structure.
  • Heavy airlaids with basis weights of> 60 g / m 2 are accordingly made up by an additional costly production step, for example by lamination with hot melt adhesives.
  • thermoplastic binding fibers predominantly based on polyolefin, prepared by dust generation (Linting) in production or packaging Difficulties as these materials are insufficient Show dust binding of very short natural fibers.
  • adhesion of these binding fibers to the polar fluff pulp fibers not sufficient due to their non-polar character, so that increased amounts of binder are necessary.
  • Simultaneous is the absorption capacity of aqueous liquids significantly reduced by the hydrophobic proportion of binding fibers, what a use as an absorption medium in hygiene articles, stands in the way of its main application areas for voluminous airlaids.
  • WO-A 90/11171 describes the production of fiber structures according to the airlaid process, natural fibers, preferably Wood fibers, sprayed with binder latex and dried, so that this completely with a thermoplastic binder layer are impregnated.
  • the consolidation of the fiber composite takes place in a second step using heat and pressure.
  • Disadvantageous with the complete impregnation is the change the physical properties of the completely covered natural fiber surface. For example, this can be the absorption capacity deteriorate the fiber composite for aqueous liquids, so that such a process does not produce Airlaids with absorbency is suitable.
  • processing conditions are not recommended in this document in which the dispersed binder particles dry because is believed that dry binders are none or show little adhesion to the fiber.
  • the invention had for its object to provide a process for the production of nonwoven fabrics by the airlaid method - with which thick and voluminous airlaid nonwovens with a weight per unit area of> 60 g / m 2 can also be accessed with optimum binding, without the need for more effort Lamination steps and without the absorption capacity of the fiber being restricted.
  • Fiber materials are suitable as fiber materials Fiber materials.
  • Polyester polyamide, glass, cellulose, cotton, wool and wood fibers.
  • Natural fibers such as are particularly preferred Cellulose, cotton, wool and wood fibers, in particular Cellulose fibers such as cellulose fibers.
  • Suitable thermoplastic polymer powders are polymers of one or more monomers from the group of vinyl esters of unbranched or branched carboxylic acids with 1 to 12 C atoms and the ester of acrylic acid and methacrylic acid with unbranched or branched alcohols with 1 to 12 carbon atoms. Short-chain vinyl esters with 1 to 4 carbon atoms are preferred in the carboxylic acid residue such as vinyl acetate, vinyl propionate, vinyl butyrate, 1-methyl vinyl acetate.
  • Methacrylic acid ester or acrylic acid ester with 1 to 4 carbon atoms in the ester residue such as methyl acrylate, methyl methacrylate, ethyl acrylate, Ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate.
  • 0.05 to 10.0% by weight can also be obtained on the total weight of the monomers, polar auxiliary monomers the group comprising ethylenically unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, Maleic acid, fumaric acid, itaconic acid, acrylamide, methacrylamide; ethylenically unsaturated sulfonic acids or their salts, preferably vinyl sulfonic acid, 2-acrylamidopropane sulfonate and N-vinyl pyrrolidone can be copolymerized.
  • polar auxiliary monomers the group comprising ethylenically unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, Maleic acid, fumaric acid, itaconic acid, acrylamide, methacrylamide; ethylenically unsaturated sulfonic acids or their salts, preferably vinyl sul
  • Hydrophilic polymers are preferred, the hydrophilicity the polymers by partial saponification of the vinyl esters or (Meth) acrylic acid ester units and optionally by a polar auxiliary monomer content is obtained in the polymer. Hydrophilic polymers are therefore those which which are at least 50% by weight of the short-chain mentioned above Contain vinyl ester or (meth) acrylic ester units or at least 5% by weight of the said polar auxiliary monomers, each based on the total weight of the monomers. For core-shell polymers the values in% by weight apply to the shell polymer.
  • hydrophobic copolymers which, in addition to the vinyl ester or (meth) acrylate comonomers, also contain one or more hydrophobic comonomers from the group comprising long-chain vinyl esters having 5 to 11 carbon atoms in the ester radical, for example vinyl -2-ethylhexanoate, vinyl laurate, vinyl pivalate and vinyl ester of alpha-branched monocarboxylic acids with 9 to 11 carbon atoms, for example VeoVa9 R or Veo-Va10 R (trade name of Shell); Vinyl aromatics, for example styrene, methylstyrene and vinyltoluene; Vinyl halides, for example vinyl chloride; Olefins, e.g.
  • the proportion of hydrophobic comonomers is at least 20% by weight, preferably 20 to 70% by weight, in each case based on the total weight of the copolymer.
  • the powdered binders are thermosetting, that means they cross-link at higher Temperature.
  • Crosslinkable comonomers are therefore also suitable, preferably in amounts of 0.05 to 10% by weight on the total weight of the monomers, such as acrylamidoglycolic acid (AGA), methacrylamidoglycolic acid methyl ester (MAGME), N-methylolacrylamide (NMA), N-methylol methacrylamide (NMMA), N-methyl olallyl carbamate, Alkyl ether of N-methylolacrylamide or N-methylolmethacrylamide such as their isobutoxy ether or n-butoxy ether.
  • AGA acrylamidoglycolic acid
  • MAGME methacrylamidoglycolic acid methyl ester
  • NMA N-methylolacrylamide
  • NMMA N-methylol methacrylamide
  • Alkyl ether of N-methylolacrylamide or N-methylolmethacrylamide such as their isobutoxy ether or
  • crosslinkable comonomers are alkoxysilane functional ones Monomers such as acryloxypropyl tri (alkoxy) and Methacryloxypropyl tri (alkoxy) silanes, vinyl trialkoxysilanes and vinyl methyl dialkoxysilanes, preferably vinyl triethoxysilane and gamma-methacryloxypropyltriethoxysilane.
  • Preferred crosslinkable comonomers are N-methylolacrylamide (NMA), N-methylolmethacrylamide (NMMA), N-methylolallyl carbamate, alkyl ether of N-methylolacrylamide or N-methylolmethacrylamide such as their isobutoxy ether or n-butoxy ether.
  • the polymer composition is chosen so that the powdered binders can be heat activated, that is, softened at elevated temperature. Therefore, the polymer composition is chosen so that a glass transition temperature Tg of -40 ° C to + 150 ° C, preferably from -20 ° C to + 50 ° C results.
  • Tg n the glass transition temperature in degrees Kelvin of the homopolymer of monomer n. Tg values for homopolymers are listed in Polymer Handbook 3rd Edition, J. Wiley & Sons, New York (1989).
  • the polymers are prepared in a known manner by bulk, solution, suspension or emulsion polymerization and optionally subsequent drying.
  • the Drying can be carried out using known methods: Suspension polymers by suction and drying; both Solution polymers by precipitation of the polymers or distillation the solvent and subsequent drying; in the case of emulsion polymers by spray drying, or by means of coagulation of the dispersion and subsequent fluid bed drying of the coagulum.
  • the polymerization is carried out in conventional reactors or pressure reactors performed in a temperature range from 30 ° C to 80 ° C and initiated with the commonly used methods.
  • the initiation takes place by means of the usual water-insoluble or water-soluble radical generator that preferably in amounts of 0.01 to 3.0% by weight, based on the Total weight of the monomers can be used.
  • examples for water-insoluble initiators are dicetyl peroxydicarbonate, Dicyclohexyl peroxydicarbonate, dibenzoyl peroxide; examples for water-soluble initiators are sodium persulfate, hydrogen peroxide, t-butyl peroxide, t-butyl hydroperoxide; Potassium peroxodiphosphate, Azobisisobutyronitrile.
  • the radical initiators mentioned in a known manner with 0.01 to 0.5% by weight, based on the total weight of the monomers, Reducing agents can be combined.
  • Reducing agents can be combined.
  • At the redox initiation is preferably one or both Redox catalyst components metered during the polymerization.
  • the polymerization takes place in the presence of the commonly used protective colloids such as Polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose, Polyvinyl pyrrolidone; during the emulsion polymerization the polymerization in the presence of those commonly used Emulsifiers are anionic, cationic and nonionic Emulsifiers.
  • the amount of protective colloids and Emulsifiers are usually from 0.5 to 6% by weight on the total weight of the monomers.
  • the polymerization can discontinuous or continuous, with or without use of seed latices, with presentation of all or individual components of the reaction mixture, or with partial submission and replenishment of the or individual components of the reaction mixture, or according to the dosing process without a template be performed.
  • the solids content of the dispersion thus obtainable is 20 to 70%.
  • the polymer dispersions are preferably dried by means of spray drying or by means of coagulation of the dispersion and subsequent fluidized bed drying of the coagulum.
  • Drying is preferred in conventional spray drying systems, where the atomization by means of one-, two- or multi-component nozzles or with a rotating disc can.
  • the outlet temperature is generally in Range from 55 ° C to 100 ° C, preferably 65 ° C to 90 ° C, depending on Plant, Tg of the resin and desired degree of dryness selected.
  • the dispersion of the polymer is used for spray drying a fixed content of preferably 20% to 70% together with Protective colloids sprayed and dried as an atomization aid become.
  • partially saponified can be used as protective colloids
  • Polyvinyl alcohols, polyvinyl pyrrolidones, starches, Melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates be used.
  • a particular advantage of suspension polymerization powder produced or dried by spray drying is because of the proportion of protective colloid water-activatable binding powder can be obtained; that is the The melt viscosity of the polymer powder can be increased by adding Reduce water.
  • water-activatable powders are used for fiber binding.
  • Not Powders that can be activated with water are better sealable binders and are used when the fiber composite is subsequently by heat sealing with another substrate to be connected.
  • the polymer powders have a melt flow index MFI (Melt Flow Index) from 2 to 300, preferably 15 to 80 g / 10 min at 190 ° C and a load weight of 2.16 kg.
  • MFI Melt Flow Index
  • To determine the MFI value is determined according to method DIN 53735 on a Göttfert MFI device Move the MPS-D model.
  • the molecular weight is 15,000 to 800,000, preferably 100,000 to 200,000.
  • the molecular weight is the weight average, determined by means of the gel permeation method (GPC) against sodium polystyrene sulfonate standards, specified.
  • the preferred grain size is 50 to 400 ⁇ m, particularly preferably 100 to 400 ⁇ m.
  • the method according to the invention can be used on conventional airlaid systems with several forming heads connected in series for blowing the fiber and / or powder mixture with air be practiced.
  • the number of forming heads is determined according to the desired basis weight of the nonwoven and process variants.
  • the fiber material can be laid out in the form of a prefabricated fiber fleece, or a first fiber layer made of loose fibers can be laid on by means of air laying. If a prefabricated nonwoven is laid out, the nonwoven is laid out, for example, in the form of knitted fabrics, scrims, spunbonded or polymer-bonded nonwoven.
  • loose fibers short fibers with a fiber length of 20 20 mm, preferably 1 to 18 mm, in particular 2 to 12 mm, are preferably used in this and the subsequent steps.
  • the weight per unit area of the nonwoven fabric or loose fibers laid out in the first step is 10 to 50 g / m 2 .
  • the fibers and the thermoplastic polymer powder are separated or deposited as a fiber / powder mixture in an air stream in an amount of 10 to 300 g / m 2 , preferably 10 to 100 g / m 2 .
  • the fibers and the fiber binding powder are dry-mixed in a turbulent airflow, continuously or discontinuously, and the mixture is then deposited in the airflow. This step can be repeated one or more times until the desired basis weight of the fleece is reached.
  • the procedure is such that the multiple application is carried out by means of a plurality of forming heads arranged one behind the other.
  • the application amount is preferably 10 to 100 g / m 2 per process step.
  • the proportion by weight of fiber binding powder is in each case 1 to 30% by weight, preferably 5 to 15% by weight, in each case based on the total weight of fiber and polymer powder.
  • the nonwovens or fibers should be laid out have a residual moisture content of 5 to 15% by weight since the residual moisture content swelling of the polymer powder and better adhesion of the polymer powder on the fiber.
  • the designed ones Non-woven fabrics or layers of fibers, either before laying on the next layer or after storing all layers, with water or steam humidified to activate the polymer powder.
  • the humidification can using steam or spraying Water, optionally combinations of the individual Procedures are used. When producing thick Steaming with hot steam is preferred for nonwovens.
  • the drying and solidification of the laid fiber material is generally carried out at temperatures from 80 ° C to 260 ° C, preferably 120 ° C to 200 ° C, optionally under a pressure of up to 100 bar, the drying temperature and the pressure to be used primarily from Depending on the type of fiber material.
  • fiber bodies with a very high basis weight are accessible by means of air laying.
  • the weight per unit area of the fiber bodies is generally from 30 g / m 2 to 1000 g / m 2 , preferably from 60 g / m 2 to 1000 g / m 2 , in particular from 60 g / m 2 to 300 g / m 2 .
  • the fiber binding powder Powdery additives are also included, for example super adsorber (SAP), fillers such as silica gel, Flame retardants, expandable microbeads or activated carbon.
  • SAP super adsorber
  • fillers such as silica gel, Flame retardants, expandable microbeads or activated carbon.
  • the fibers and the fiber binding powder can be deposited in a mixture in an air stream to form a textile fabric and then the fiber structure can be sprayed with an aqueous polymer dispersion instead of water activation or in addition to water activation.
  • the procedure here can be such that polymer powder and polymer dispersion have the same polymer base;
  • it is also possible to use different polymers from the group of the above-mentioned vinyl ester or methacrylic acid ester polymers for example depositing a water-activatable powder with the fibers and spraying this fiber structure with an aqueous dispersion of a non-water-activatable but sealable polymer.
  • the polymer dispersion is included a fixed content of preferably 7 to 30%.
  • the amount of polymer dispersion used is preferably 2 to 25% by weight of the fiber content.
  • the drying and solidification takes place analogous to the procedure described above. This process variant is preferred when very thick fiber structures be made, or if the nonwovens in a next Process step to be laminated.
  • the fiber structures are given in the above Way, with or without spraying of polymer dispersion, treated and then another substrate hung up.
  • the laminates are consolidated under the temperature and pressure conditions given above.
  • lamination can be two identical or different fiber structures are glued together or a fiber structure with be glued to another substrate.
  • plastic films such as polyester films or polyolefin films, Fabrics and nonwovens such as cellulose fleeces, fiberboard such as chipboard, foamed sheet materials like polyurethane foams.
  • the products accessible by the process according to the invention are suitable for use in the automotive industry or in the construction sector, for example as insulation or for use in hygiene area, for example for the production of diapers or sanitary napkins.
  • the non-woven fabrics can save costs in an integrated manufacturing process can be processed further, for example to form laminates yourself or other fleeces while maintaining multifunctional Composites.
  • the polymer powders also have binding capacity for functional, powdery additives, which are often found in nonwovens are included and can be due to the tie even distribution effectively. Compared to Conventional binding fibers are obtained when using the binding powder better adhesion to natural fibers, improved dust binding without the absorption capacity of the airlaid being restricted becomes.
  • An airlaid made of cellulose fibers (fiber length 2 to 12 mm) with a basis weight of 100 g / m 2 was, with 10 wt .-% (s / s), based on the total weight of fiber and polymer, an aqueous dispersion of a self-crosslinking vinyl acetate-ethylene -NMA copolymers sprayed on both sides and then dried in a drying cabinet at a temperature of 180 ° C and without pressure.
  • the strength of the nonwoven was tested with a peel seam test. For this purpose, 40 mm wide strips were produced and then 5 individual strips were tested according to ISO 9073-3 and the average was determined.
  • the peel seam strength of the airlaid was 0.15 N / cm.
  • Cellulose fibers (fiber length 2 to 12 mm) were laid out in a basis weight of 50 g / m 2 and then a layer of cellulose fiber in a basis weight of 50 g / m 2 with an additional 20% by weight, based on the fiber / powder mixture Total weight of fiber and powder, a powdery vinyl acetate-diisopropyl fumarate copolymer with 30 wt .-% diisopropyl fumarate.
  • the fleece was dried in the drying cabinet under the same conditions as in Comparative Example 1.
  • the peel strength was 0.38 N / cm. Although non-crosslinkable binder was used, the peel seam strength was significantly increased in comparison with comparative example 1.
  • Example 2 The procedure was analogous to Example 2, with the difference that that after laying out the fleece and before drying 30th % By weight of water, based on the total weight of fiber and Powder that were sprayed on.
  • the peel seam strength increased again and was 0.41 N / cm.
  • Example 2 The procedure was analogous to Example 2, with the difference that that 10 wt .-%, based on the total weight of fiber and Powder, a 70:30 mixture (w / w) of the powdered binder according to example 2 and a SAP powder (Famor SX FAM) was used. Despite the high percentage of SAP powder the peel seam strength of 0.30 N / cm is significantly higher than that of the Use of a larger amount of crosslinkable binder dispersion (Comparative Example 1). It wasn't dusting the Superadsorber powder either noticeable.
  • Example 2 The procedure was analogous to Example 2, with the difference that that 10 wt .-%, based on the total weight of fiber and Powder, a powdery, hydrophobic polyolefin copolymer (PE / PP) were used.
  • the peel seam strength was with 0.08 N / cm compared to the vinyl ester or (meth) acrylic ester polymers significantly reduced.
  • Fig. 1 is a SEM picture of one with PE / PP bicomponent fibers thermally consolidated airlaids (100 g / m2). The poor wetting of the fluff pulp is good too detect.
  • Fig. 2 shows an airlaid (100 g / m 2 ) consolidated with a powdered binder (example 3), which has very good wetting of the fibers.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Nonwoven Fabrics (AREA)
  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Herstellung von Faservliesen nach dem Airlaidverfahren, wobei Fasern und pulverförmiges Bindemittel im Luftstrom abgelegt werden, und die damit erhältlichen Vliese sowie deren Verwendung.The invention relates to a method for producing nonwoven fabrics after the airlaid process, with fibers and powder Binding agents are placed in the air flow, and with it available nonwovens and their use.

Die WO-A 96/39553 beschreibt den Stand der Technik zur Herstellung von luftgelegten Vliesstoffen nach dem Airlaidverfahren, welche ihre Anwendung beispielsweise in Hygieneprodukten, Haushaltsartikeln oder in Filtermedien finden. Dazu werden natürliche Fasern, beispielsweise Cellulosefasern (Fluffpulp), mit Luft auf ein Drahtband aufgeblasen, die Luft abgezogen und das so erhaltene flächige Fasergebilde mit einem wäßrigen Bindemittel oder thermoplastischen Fasern, unter Einfluß von Wärme, Druck und/oder Wasserstrahlen, verfestigt. Die WO-A 96/39553 selbst betrifft die Herstellung von Nonwovens nach dem Airlaidverfahren, wobei zur Faserbindung eine wäßrige Polymerdispersion eingesetzt wird und die Eindringtiefe des Latexbinders in das ausgelegte Fasergebilde durch den Sprühdruck bzw. das angelegte Vakuum gesteuert wird.WO-A 96/39553 describes the prior art for production air-laid nonwovens using the airlaid process, which are used for example in hygiene products, Find household items or in filter media. This will be natural Fibers, for example cellulose fibers (fluff pulp), inflated to a wire band with air, the air drawn off and the flat fiber structure thus obtained with an aqueous binder or thermoplastic fibers, under the influence of heat, Pressure and / or water jets, solidified. The WO-A 96/39553 itself relates to the manufacture of nonwovens the airlaid process, with an aqueous polymer dispersion for fiber binding is used and the penetration depth of the latex binder into the laid out fiber structure by the spray pressure or the vacuum applied is controlled.

Nachteilig bei den nur mit wäßrigen Bindemitteln gebundenen Airlaids ist die mangelnde Durchbindung des Vlieses bei hohen Flächengewichten, so daß es zur Delaminierung der Vliesschichten im Innern kommen kann. Der Grund dafür ist, daß bei dicken Vliesen der Polymeranteil der Binderdispersion nicht durchgeht und ins Innere des Fasergebildes nur Wasser eindringt. Schwere Airlaids mit Flächengewichten von > 60 g/m2 werden dementsprechend durch einen zusätzlichen kostenaufwendigen Produktionsschritt, beispielsweise mittels Kaschierung mit Schmelzklebern konfektioniert.A disadvantage of the airlaids which are only bound with aqueous binders is the lack of binding of the nonwoven at high basis weights, so that delamination of the nonwoven layers inside can occur. The reason for this is that in the case of thick nonwovens, the polymer portion of the binder dispersion does not go through and only water penetrates into the interior of the fiber structure. Heavy airlaids with basis weights of> 60 g / m 2 are accordingly made up by an additional costly production step, for example by lamination with hot melt adhesives.

Die Bindung von Airlaids mit thermoplastischen Bindefasern, überwiegend auf Polyolefinbasis, bereitet durch die Staubentwicklung (Linting) bei der Produktion bzw. Konfektionierung Schwierigkeiten, da diese Materialien nur eine ungenügende Staubbindung von sehr kurzen Naturfasern aufweisen. Desgleichen ist die Haftung dieser Bindefasern auf den polaren Fluffpulp-Fasern aufgrund ihres unpolaren Charakters nicht ausreichend, so daß erhöhte Bindemittelmengen nötig sind. Gleichzeitg wird das Aufnahmevermögen von wäßrigen Flüssigkeiten durch den hydrophoben Bindefaseranteil deutlich verringert, was einer Verwendung als Absorptionsmedium in Hygieneartikeln, seinem der Hauptanwendungsgebiete für voluminöse Airlaids, entgegensteht.The binding of airlaids with thermoplastic binding fibers, predominantly based on polyolefin, prepared by dust generation (Linting) in production or packaging Difficulties as these materials are insufficient Show dust binding of very short natural fibers. The same is the adhesion of these binding fibers to the polar fluff pulp fibers not sufficient due to their non-polar character, so that increased amounts of binder are necessary. Simultaneous is the absorption capacity of aqueous liquids significantly reduced by the hydrophobic proportion of binding fibers, what a use as an absorption medium in hygiene articles, stands in the way of its main application areas for voluminous airlaids.

Die WO-A 90/11171 beschreibt die Herstellung von Fasergebilden nach dem Airlaidverfahren, wobei Naturfasern, vorzugsweise Holzfasern, mit Binderlatex besprüht und getrocknet werden, so daß diese vollständig mit einer thermoplastischen Binderschicht imprägniert sind. Die Verfestigung des Faserverbundes erfolgt in einem zweiten Schritt durch Wärme und Druck. Nachteilig bei der vollständigen Imprägnierung ist die Veränderung der physikalischen Eigenschaften der vollständig umhüllten Naturfaseroberfläche. Dies kann zum Beispiel das Aufnahmevermögen des Faserverbundes für wäßrige Flüssigkeiten verschlechtern, so daß ein solches Verfahren nicht zur Herstellung von Airlaids mit Absorptionsvermögen geeignet ist. Darüberhinaus wird in dieser Schrift von Verarbeitungsbedingungen abgeraten bei denen die dispergierten Bindemittelteilchen trocknen, da die Ansicht vertreten wird, daß trockene Bindemittel keine oder nur geringe Haftung an der Faser zeigen.WO-A 90/11171 describes the production of fiber structures according to the airlaid process, natural fibers, preferably Wood fibers, sprayed with binder latex and dried, so that this completely with a thermoplastic binder layer are impregnated. The consolidation of the fiber composite takes place in a second step using heat and pressure. Disadvantageous with the complete impregnation is the change the physical properties of the completely covered natural fiber surface. For example, this can be the absorption capacity deteriorate the fiber composite for aqueous liquids, so that such a process does not produce Airlaids with absorbency is suitable. Furthermore processing conditions are not recommended in this document in which the dispersed binder particles dry because is believed that dry binders are none or show little adhesion to the fiber.

Die Verwendung von pulverförmigen Bindemitteln wie Phenoplastpulver oder Polypropylenpulver ist bei der Herstellung von Krempelvliesen (Wirrvlieskarden) bekannt. Beispielsweise werden in der WO-A 90/14457 Glasfasern mit einer Krempelvorrichtung zu einem Wirrvlies ausgelegt und mit Pulver bestreut. Das pulverhaltige Vlies wird anschließend so gefaltet, daß mehere Lagen übereinander liegen und durch Hitze- und Druckeinwirkung verfestigt. Die Kardierung von Fasern wird im Gegensatz zum Airlaidverfahren zur Herstellung von sehr dicken Faserkörpern mit einem Flächengewicht von 2000 bis 4000 g/m2 eingesetzt, wobei im allgemeinen Fasern mit einer Faserlänge von > 20 mm verarbeitet werden. Nachteilig ist die aufwendige Ablagetechnik, welche auch bei geringeren Flächengewichten, wie sie für Airlaidprodukte charakteristisch sind, ein unregelmäßiges Vlies ergibt, dessen Unregelmäßigkeiten sich erst mit zunehmendem Flächengewicht ausgleichen.The use of powdered binders such as phenolic powder or polypropylene powder is known in the production of carded nonwovens (tangled nonwoven cards). For example, in WO-A 90/14457 glass fibers are laid out with a carding device to form a tangled nonwoven and sprinkled with powder. The powder-containing fleece is then folded in such a way that several layers lie on top of one another and are consolidated by the action of heat and pressure. In contrast to the airlaid process, the carding of fibers is used for the production of very thick fiber bodies with a basis weight of 2000 to 4000 g / m 2 , whereby fibers with a fiber length of> 20 mm are generally processed. A disadvantage is the complex filing technique, which results in an irregular fleece even with lower basis weights, which are characteristic of airlaid products, the irregularities of which only compensate for themselves with increasing basis weight.

Die Verwendung von vernetzbaren Polymerpulvern in Verfahren, worin das Pulver in vorher ausgelegte, gegebenenfalls vorverfestigte, Fasermaterialien nachträglich eingestreut wird, ist in der EP-B 687317 und der EP-A 894888 beschrieben. Nachteilig ist, daß mittels Auslegen einer Faser/Pulver-Mischung im Airlaidprozeß große Pulververluste auftreten und dickere Airlaids mittels einfachen Auslegens einer Faser/Pulver-Mischung nicht zugänglich sind, sondern die dabei erhältlichen Produkte aufwendig laminiert werden müßten.The use of crosslinkable polymer powders in processes wherein the powder in previously designed, optionally pre-consolidated, Fiber materials is subsequently sprinkled in in EP-B 687317 and EP-A 894888. Disadvantageous is that by laying out a fiber / powder mixture in the airlaid process large powder losses occur and thicker airlaids by simply laying out a fiber / powder mixture are accessible, but the products available are expensive should be laminated.

Der Erfindung lag die Aufgabe zugrunde, ein Verfahren zur Herstellung von Faservliesen nach dem Airlaid-Verfahren zur Verfügung zu stellen-mit dem auch dicke und voluminöse Airlaidvliese mit einem Flächengewicht von > 60 g/m2 mit optimaler Durchbindung zugänglich werden, ohne die Notwendigkeit aufwendiger Laminierungsschritte und ohne daß die Absorptionsfähigkeit der Faser eingeschränkt wird.The invention had for its object to provide a process for the production of nonwoven fabrics by the airlaid method - with which thick and voluminous airlaid nonwovens with a weight per unit area of> 60 g / m 2 can also be accessed with optimum binding, without the need for more effort Lamination steps and without the absorption capacity of the fiber being restricted.

Gegenstand der Erfindung ist ein Verfahren zur Herstellung von Faservliesen nach dem Airlaidverfahren wobei die Fasern und das pulverförmige Bindemittel in einem Luftstrom abgelegt werden, dadurch gekennzeichnet, daß

  • a) in einem ersten Verfahrensschritt ein Faservlies oder Fasern bis zu einem Flächengewicht von 10 bis 50 g/m2 ausgelegt werden,
  • b) im nächsten Schritt Fasern und ein thermoplastisches Polymerpulver auf der Basis von Polymerisaten von einem oder mehreren Monomeren aus der Gruppe der Vinylester und (Meth)Acrylsäureester getrennt oder als Mischung im Luftstrom in einer Menge von 10 bis 300 g/m2 abgelegt werden und dieser Schritt gegebenenfalls so oft wiederholt wird, bis das gewünschte Flächengewicht erhalten wird, und
  • c) das Fasermaterial bei Temperaturen von 80°C bis 260°C und gegebenenfalls bei einem Druck von bis zu 100 bar verfestigt wird.
    • The invention relates to a process for the production of nonwovens by the airlaid process, the fibers and the powdery binder being deposited in an air stream, characterized in that
  • a) in a first process step, a nonwoven fabric or fibers up to a basis weight of 10 to 50 g / m 2 are laid out,
  • b) in the next step fibers and a thermoplastic polymer powder based on polymers of one or more monomers from the group of vinyl esters and (meth) acrylic acid esters are separated or deposited as a mixture in an air stream in an amount of 10 to 300 g / m 2 and this step may be repeated until the desired basis weight is obtained, and
  • c) the fiber material is solidified at temperatures of 80 ° C to 260 ° C and optionally at a pressure of up to 100 bar.

    • Als Fasermaterialien geeignet sind alle natürlichen und synthetischen Fasermaterialien. Eine Beschränkung bei der Auswahl an Fasermaterialien besteht a priori nicht; es kommen alle Faserrohstoffe in Betracht, die in der Nonwoven-Industrie zum Einsatz kommen, beispielsweise Polyester-, Polyamid-, Polypropylen-, Polyethylen-, Glas-, Keramik-, Viskose-, Carbon-, Cellulose-, Baumwolle-, Wolle- und Holzfasern. Bevorzugt werden Polyester-, Polyamid-, Glas-, Cellulose-, Baumwolle-, Wolle- und Holzfasern. Besonders bevorzugt werden Naturfasern wie Cellulose-, Baumwolle-, Wolle- und Holzfasern, insbesondere Cellulosefasern wie Zellstofffasern.All natural and synthetic materials are suitable as fiber materials Fiber materials. A choice limitation a priori there is no fiber material; all fiber raw materials come considered in the nonwoven industry at Are used, for example polyester, polyamide, polypropylene, Polyethylene, glass, ceramic, viscose, carbon, cellulose, Cotton, wool and wood fibers. To be favoured Polyester, polyamide, glass, cellulose, cotton, wool and wood fibers. Natural fibers such as are particularly preferred Cellulose, cotton, wool and wood fibers, in particular Cellulose fibers such as cellulose fibers.

    Geeignete thermoplastische Polymerpulver sind Polymerisate von einem oder mehreren Monomeren aus der Gruppe der Vinylester von unverzweigten oder verzweigten Carbonsäuren mit 1 bis 12 C-Atomen und der Ester der Acrylsäure und Methacrylsäure mit unverzweigten oder verzweigten Alkoholen mit 1 bis 12 C-Atomen. Bevorzugt sind kurzkettige Vinylester mit 1 bis 4 C-Atomen im Carbonsäurerest wie Vinylacetat, Vinylpropionat, Vinylbutyrat, 1-Methylvinylacetat. Bevorzugt sind auch kurzkettige Methacrylsäureester oder Acrylsäureester mit 1 bis 4 C-Atomen im Esterrest wie Methylacrylat, Methylmethacrylat, Ethylacrylat, Ethylmethacrylat, Propylacrylat, Propylmethacrylat, n-Butylacrylat, n-Butylmethacrylat.Suitable thermoplastic polymer powders are polymers of one or more monomers from the group of vinyl esters of unbranched or branched carboxylic acids with 1 to 12 C atoms and the ester of acrylic acid and methacrylic acid with unbranched or branched alcohols with 1 to 12 carbon atoms. Short-chain vinyl esters with 1 to 4 carbon atoms are preferred in the carboxylic acid residue such as vinyl acetate, vinyl propionate, vinyl butyrate, 1-methyl vinyl acetate. Short-chain ones are also preferred Methacrylic acid ester or acrylic acid ester with 1 to 4 carbon atoms in the ester residue such as methyl acrylate, methyl methacrylate, ethyl acrylate, Ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate.

    Gegebenenfalls können auch noch 0.05 bis 10.0 Gew%, bezogen auf das Gesamtgewicht der Monomeren, polarer Hilfsmonomere aus der Gruppe umfassend ethylenisch ungesättigte Mono- und Dicarbonsäuren und deren Amide, wie Acrylsäure, Methacrylsäure, Maleinsäure, Fumarsäure, Itaconsäure, Acrylamid, Methacrylamid; ethylenisch ungesättigte Sulfonsäuren bzw. deren Salze, vorzugsweise Vinylsulfonsäure, 2-Acrylamidopropansulfonat und N-Vinylpyrrolidon copolymerisiert werden.If necessary, 0.05 to 10.0% by weight can also be obtained on the total weight of the monomers, polar auxiliary monomers the group comprising ethylenically unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, Maleic acid, fumaric acid, itaconic acid, acrylamide, methacrylamide; ethylenically unsaturated sulfonic acids or their salts, preferably vinyl sulfonic acid, 2-acrylamidopropane sulfonate and N-vinyl pyrrolidone can be copolymerized.

    Bevorzugt werden hydrophile Polymerisate, wobei die Hydrophilie der Polymerisate durch Teilverseifung der Vinylester bzw. (Meth)acrylsäureester-Einheiten sowie gegebenenfalls durch einen polaren Hilfsmonomeranteil im Polymerisat erhalten wird. Als hydrophile Polymerisate werden daher solche bezeichnet, welche mindestens 50 Gew.-% der obengenannten kurzkettigen Vinylester- oder (Meth)acrylsäureester-Einheiten enthalten oder mindestens 5 Gew.-% der genannten polaren Hilfsmonomere, jeweils bezogen auf das Gesamtgewicht der Monomere. Bei Kern-Schale-Polymerisaten gelten die genannten Werte in Gew.-% für das Schalenpolymer.Hydrophilic polymers are preferred, the hydrophilicity the polymers by partial saponification of the vinyl esters or (Meth) acrylic acid ester units and optionally by a polar auxiliary monomer content is obtained in the polymer. Hydrophilic polymers are therefore those which which are at least 50% by weight of the short-chain mentioned above Contain vinyl ester or (meth) acrylic ester units or at least 5% by weight of the said polar auxiliary monomers, each based on the total weight of the monomers. For core-shell polymers the values in% by weight apply to the shell polymer.

    Insbesondere für Anwendungen im Baubereich können gegebenenfalls hydrophobe Copolymere eingesetzt werden, welche neben den Vinylester- bzw. (Meth)acrylat-Comonomeren noch ein oder mehrere hydrophobe Comonomere enthalten aus der Gruppe umfassend langkettige Vinylester mit 5 bis 11 C-Atomen im Esterrest, beispielsweise Vinyl-2-ethylhexanoat, Vinyllaurat, Vinylpivalat und Vinylester von alpha-verzweigten Monocarbonsäuren mit 9 bis 11 C-Atomen, beispielsweise VeoVa9R oder Veo-Va10R (Handelsnamen der Firma Shell); Vinylaromaten, beispielsweise Styrol, Methylstyrol und Vinyltoluol; Vinylhalogenide, beispielsweise Vinylchlorid; Olefine, beispielsweise Ethylen und Propylen; Diene, beispielsweise 1.3-Butadien und Isopren; sowie Diester von Dicarbonsäuren wie Fumarsäure oder Maleinsäure, beispielsweise Dibutylmaleat und Diisopropylfumarat. Im allgemeinen beträgt der Anteil an hydrophoben Comonomeren mindestens 20 Gew.-%, vorzugsweise 20 bis 70 Gew.-%, jeweils bezogen auf das Gesamtgewicht des Copolymers.In particular for applications in the construction sector, it is optionally possible to use hydrophobic copolymers which, in addition to the vinyl ester or (meth) acrylate comonomers, also contain one or more hydrophobic comonomers from the group comprising long-chain vinyl esters having 5 to 11 carbon atoms in the ester radical, for example vinyl -2-ethylhexanoate, vinyl laurate, vinyl pivalate and vinyl ester of alpha-branched monocarboxylic acids with 9 to 11 carbon atoms, for example VeoVa9 R or Veo-Va10 R (trade name of Shell); Vinyl aromatics, for example styrene, methylstyrene and vinyltoluene; Vinyl halides, for example vinyl chloride; Olefins, e.g. ethylene and propylene; Dienes, for example 1,3-butadiene and isoprene; and diesters of dicarboxylic acids such as fumaric acid or maleic acid, for example dibutyl maleate and diisopropyl fumarate. In general, the proportion of hydrophobic comonomers is at least 20% by weight, preferably 20 to 70% by weight, in each case based on the total weight of the copolymer.

    Die pulverförmigen Bindemittel sind in einer bevorzugten Ausführungsform wärmehärtbar, das heißt sie vernetzen bei erhöhter Temperatur. Geeignet sind deshalb auch vernetzbare Comonomere, vorzugsweise in Mengen von 0.05 bis 10 Gew.-%, bezogen auf das Gesamtgewicht der Monomere, wie Acrylamidoglykolsäure (AGA), Methacrylamidoglykolsäuremethylester (MAGME), N-Methylolacrylamid (NMA), N-Methylolmethacrylamid (NMMA), N-Methylolallylcarbamat, Alkylether von N-Methylolacrylamid oder N-Methylolmethacrylamid wie deren Isobutoxyether oder n-Butoxyether. Weitere Beispiele für vernetzbare Comonomere sind Alkoxysilan-funktionelle Monomere wie Acryloxypropyltri(alkoxy)-und Methacryloxypropyltri(alkoxy)-Silane, Vinyltrialkoxysilane und Vinylmethyldialkoxysilane, vorzugsweise Vinyltriethoxysilan und gamma-Methacryloxypropyltriethoxysilan. Bevorzugte vernetzbare Comonomere sind N-Methylolacrylamid (NMA), N-Methylolmethacrylamid (NMMA), N-Methylolallylcarbamat, Alkylether von N-Methylolacrylamid oder N-Methylolmethacrylamid wie deren Isobutoxyether oder n-Butoxyether.In a preferred embodiment, the powdered binders are thermosetting, that means they cross-link at higher Temperature. Crosslinkable comonomers are therefore also suitable, preferably in amounts of 0.05 to 10% by weight on the total weight of the monomers, such as acrylamidoglycolic acid (AGA), methacrylamidoglycolic acid methyl ester (MAGME), N-methylolacrylamide (NMA), N-methylol methacrylamide (NMMA), N-methyl olallyl carbamate, Alkyl ether of N-methylolacrylamide or N-methylolmethacrylamide such as their isobutoxy ether or n-butoxy ether. Further examples of crosslinkable comonomers are alkoxysilane functional ones Monomers such as acryloxypropyl tri (alkoxy) and Methacryloxypropyl tri (alkoxy) silanes, vinyl trialkoxysilanes and vinyl methyl dialkoxysilanes, preferably vinyl triethoxysilane and gamma-methacryloxypropyltriethoxysilane. Preferred crosslinkable comonomers are N-methylolacrylamide (NMA), N-methylolmethacrylamide (NMMA), N-methylolallyl carbamate, alkyl ether of N-methylolacrylamide or N-methylolmethacrylamide such as their isobutoxy ether or n-butoxy ether.

    Die Polymerzusammensetzung wird so gewählt, daß die pulverförmigen Bindemittel wärmeaktivierbar sind, das heißt bei erhöhter Temperatur erweichen. Deshalb wird die Polymerzusammensetzung so gewählt, daß eine Glasübergangstemperatur Tg von -40°C bis +150°C, vorzugsweise von -20°C bis +50°C, resultiert. Die Glasübergangstemperatur Tg der Polymerisate kann in bekannter Weise mittels Differential Scanning Calorimetry (DSC) ermittelt werden. Die Tg kann auch mittels der Fox-Gleichung näherungsweise vorausberechnet werden. Nach Fox T. G., Bull. Am. Physics Soc. 1, 3, page 123 (1956) gilt: 1/Tg = x1/Tg1 + x2/Tg2 + ... + xn/Tgn, wobei xn für den Massebruch (Gew%/100) des Monomers n steht, und Tgn die Glasübergangstemperatur in Grad Kelvin des Homopolymers des Monomer n ist. Tg-Werte für Homopolymerisate sind in Polymer Handbook 3nd Edition, J. Wiley & Sons, New York (1989) aufgeführt.The polymer composition is chosen so that the powdered binders can be heat activated, that is, softened at elevated temperature. Therefore, the polymer composition is chosen so that a glass transition temperature Tg of -40 ° C to + 150 ° C, preferably from -20 ° C to + 50 ° C results. The glass transition temperature Tg of the polymers can be determined in a known manner by means of differential scanning calorimetry (DSC). The Tg can also be roughly predicted using the Fox equation. According to Fox TG, Bull. Am. Physics Soc. 1 , 3, page 123 (1956) applies: 1 / Tg = x 1 / Tg 1 + x 2 / Tg 2 + ... + x n / Tg n , where x n is the mass fraction (wt% / 100) of the Monomer n, and Tg n is the glass transition temperature in degrees Kelvin of the homopolymer of monomer n. Tg values for homopolymers are listed in Polymer Handbook 3rd Edition, J. Wiley & Sons, New York (1989).

    Als hydrophile Polymerisate werden die nachstehend aufgeführten bevorzugt, wobei sich die Angaben in Gewichtsprozent, gegebenenfalls mit dem Anteil an polaren oder vernetzbaren Hilfsmonomeren, auf 100 Gew.-% aufaddieren:

  • Vinylacetat-Polymerisate, gegebenenfalls mit einem Gehalt an N-Methylolacrylamid von 0.05 bis 10 Gew.-%;
  • Vinylacetat-Ethylen-Copolymere mit einem Ethylengehalt von 1 bis 30 Gew.-%, gegebenenfalls mit einem Gehalt an N-Methylolacrylamid von 0.05 bis 10 Gew.-%;
  • Vinylacetat-Ethylen-Vinylchlorid-Copolymere mit einem Ethylengehalt und Vinylchlorid-Gehalt von zusammen 5 bis 30 Gew.-%;
  • Vinylacetat-Acrylat-Copolymere mit einem oder mehreren kurzkettigen Acrylsäureestern aus der Gruppe Methylacrylat, Ethylacrylat, Propylacrylat, Butylacrylat;
  • Acrylsäureester-Polymerisate von einem oder mehreren kurzkettigen Acrylsäureestern aus der Gruppe Methylacrylat, Ethylacrylat, Propylacrylat, Butylacrylat, gegebenenfalls mit einem Gehalt an N-Methylolacrylamid von 0.05 bis 10 Gew.-%.
    • The following are preferred as hydrophilic polymers, the details in percent by weight, optionally with the proportion of polar or crosslinkable auxiliary monomers, adding up to 100% by weight:
  • Vinyl acetate polymers, optionally with an N-methylolacrylamide content of 0.05 to 10% by weight;
  • Vinyl acetate-ethylene copolymers with an ethylene content of 1 to 30% by weight, optionally with a content of N-methylolacrylamide of 0.05 to 10% by weight;
  • Vinyl acetate-ethylene-vinyl chloride copolymers with an ethylene content and vinyl chloride content of altogether 5 to 30% by weight;
  • Vinyl acetate-acrylate copolymers with one or more short-chain acrylic acid esters from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate;
  • Acrylic acid ester polymers of one or more short-chain acrylic acid esters from the group of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, optionally with a content of N-methylolacrylamide of 0.05 to 10% by weight.

    • Als hydrophobe Polymerisate werden die nachstehend aufgeführten bevorzugt, wobei sich die Angaben in Gewichtsprozent, gegebenenfalls mit dem Anteil an vernetzbaren Hilfsmonomeren, auf 100 Gew.-% aufaddieren:

  • Vinylacetat-Copolymerisate, mit 20 bis 50 Gew.-% Diestern von Dicarbonsäuren, insbesondere Dibutylmaleat und/oder Diisopropylfumarat, welche gegebenenfalls noch 1 bis 15 Gew.-% Ethylen enthalten;
  • Vinylacetat-Copolymere mit 20 bis 50 Gew.-% von einem oder mehrerer copolymerisierbarer Vinylestern wie Vinyllaurat, Vinylpivalat, Vinyl-2-ethylhexansäureester, Vinylester einer alpha-verzweigten Carbonsäure, insbesonders Versaticsäure-Vinylester (VeoVa9R, VeoVa10R, VeoVa11R), welche gegebenenfalls noch 5 bis 30 Gew% Ethylen enthalten;
  • Styrol-Acrylsäureester-Copolymere wie Styrol-n-Butylacrylat oder Styrol-2-Ethylhexylacrylat mit einem Styrol-Gehalt von jeweils 30 bis 70 Gew%.
    • The following are preferred as hydrophobic polymers, the details in percent by weight, optionally with the proportion of crosslinkable auxiliary monomers, adding up to 100% by weight:
  • Vinyl acetate copolymers with 20 to 50% by weight diesters of dicarboxylic acids, in particular dibutyl maleate and / or diisopropyl fumarate, which may also contain 1 to 15% by weight of ethylene;
  • Vinyl acetate copolymers with 20 to 50% by weight of one or more copolymerizable vinyl esters such as vinyl laurate, vinyl pivalate, vinyl 2-ethylhexanoic acid ester, vinyl ester of an alpha-branched carboxylic acid, in particular vinyl acetate versatic acid (VeoVa9 R , VeoVa10 R , VeoVa11 R ), which may also contain 5 to 30% by weight of ethylene;
  • Styrene-acrylic acid ester copolymers such as styrene-n-butyl acrylate or styrene-2-ethylhexyl acrylate, each with a styrene content of 30 to 70% by weight.

    • Die Herstellung der Polymerisate erfolgt in bekannter Weise mittels Masse-, Lösungs-, Suspensions- oder Emulsionspolymerisation und gegebenenfalls anschließender Trocknung. Die Trocknung kann mittels bekannter Verfahren erfolgen: Bei der Suspensionspolymerisaten durch Absaugen und Trocknung; bei den Lösungspolymerisaten durch Ausfällen der Polymerisate oder Abdestillation des Lösungsmittels und anschließender Trocknung; bei den Emulsionspolymerisaten mittels Sprühtrocknung, oder mittels Koagulation der Dispersion und anschließender Wirbelschichttrocknung des Koagulats.The polymers are prepared in a known manner by bulk, solution, suspension or emulsion polymerization and optionally subsequent drying. The Drying can be carried out using known methods: Suspension polymers by suction and drying; both Solution polymers by precipitation of the polymers or distillation the solvent and subsequent drying; in the case of emulsion polymers by spray drying, or by means of coagulation of the dispersion and subsequent fluid bed drying of the coagulum.

    Die Polymerisation wird in herkömmlichen Reaktoren oder Druckreaktoren in einem Temperaturbereich von 30°C bis 80°C durchgeführt und mit den üblicherweise eingesetzten Methoden eingeleitet. Die Initiierung erfolgt mittels der gebräuchlichen, wasserunlöslichen oder wasserlöslichen Radikalbildner, die vorzugsweise in Mengen von 0.01 bis 3.0 Gew% bezogen auf das Gesamtgewicht der Monomeren, eingesetzt werden. Beispiele für wasserunlösliche Initiatoren sind Dicetylperoxydicarbonat, Dicyclohexylperoxydicarbonat, Dibenzoylperoxid; Beispiele für wasserlösliche Initiatoren sind Natriumpersulfat, Wasserstoffperoxid, t-Butylperoxid, t-Butylhydroperoxid; Kaliumperoxodiphosphat, Azobisisobutyronitril. Gegebenenfalls können die genannten radikalischen Initiatoren auch in bekannter Weise mit 0.01 bis 0.5 Gew%, bezogen auf das Gesamtgewicht der Monomeren, Reduktionsmittel kombiniert werden. Geeignet sind zum Beispiel Alkaliformaldehydsulfoxylate und Ascorbinsäure. Bei der Redoxinitiierung werden dabei vorzugsweise eine oder beide RedoxKatalysatorkomponenten während der Polymerisation dosiert.The polymerization is carried out in conventional reactors or pressure reactors performed in a temperature range from 30 ° C to 80 ° C and initiated with the commonly used methods. The initiation takes place by means of the usual water-insoluble or water-soluble radical generator that preferably in amounts of 0.01 to 3.0% by weight, based on the Total weight of the monomers can be used. examples for water-insoluble initiators are dicetyl peroxydicarbonate, Dicyclohexyl peroxydicarbonate, dibenzoyl peroxide; examples for water-soluble initiators are sodium persulfate, hydrogen peroxide, t-butyl peroxide, t-butyl hydroperoxide; Potassium peroxodiphosphate, Azobisisobutyronitrile. If necessary, the radical initiators mentioned in a known manner with 0.01 to 0.5% by weight, based on the total weight of the monomers, Reducing agents can be combined. Are suitable for Example alkali formaldehyde sulfoxylates and ascorbic acid. At the redox initiation is preferably one or both Redox catalyst components metered during the polymerization.

    Bei der Suspensionspolymerisation erfolgt die Polymerisation in Gegenwart der üblicherweise verwendeten Schutzkolloide wie Polyvinylalkohol, Cellulosederivate wie Hydroxyethylcellulose, Polyvinylpyrrolidon; bei der Emulsionspolymerisation erfolgt die Polymerisation in Gegenwart der üblicherweise verwendeten Emulgatoren, das sind anionische, kationische als auch nichtionische Emulgatoren. Die Einsatzmenge von Schutzkolloiden und Emulgatoren betragen normalerweise von 0.5 bis 6 Gew%, bezogen auf das Gesamtgewicht der Monomeren. Die Polymerisation kann diskontinuierlich oder kontinuierlich, mit oder ohne Verwendung von Saatlatices, unter Vorlage aller oder einzelner Bestandteile des Reaktionsgemisches, oder unter teilweiser Vorlage und Nachdosierung der oder einzelner Bestandteile des Reaktionsgemisches, oder nach dem Dosierverfahren ohne Vorlage durchgeführt werden. Der Festgehalt der so erhältlichen Dispersion beträgt 20 bis 70 %.In the case of suspension polymerization, the polymerization takes place in the presence of the commonly used protective colloids such as Polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose, Polyvinyl pyrrolidone; during the emulsion polymerization the polymerization in the presence of those commonly used Emulsifiers are anionic, cationic and nonionic Emulsifiers. The amount of protective colloids and Emulsifiers are usually from 0.5 to 6% by weight on the total weight of the monomers. The polymerization can discontinuous or continuous, with or without use of seed latices, with presentation of all or individual components of the reaction mixture, or with partial submission and replenishment of the or individual components of the reaction mixture, or according to the dosing process without a template be performed. The solids content of the dispersion thus obtainable is 20 to 70%.

    Die Trocknung der Polymerdispersionen erfolgt vorzugsweise mittels Sprühtrocknung oder mittels Koagulation der Dispersion und anschließender Wirbelschichttrocknung des Koagulats. Zur Trocknung bevorzugt wird die Sprühtrocknung in üblichen Sprühtrocknungsanlagen, wobei die Zerstäubung mittels Ein-, Zwei- oder Mehrstoffdüsen oder mit einer rotierenden Scheibe erfolgen kann. Die Austrittstemperatur wird im allgemeinen im Bereich von 55°C bis 100°C, bevorzugt 65°C bis 90°C, je nach Anlage, Tg des Harzes und gewünschtem Trocknungsgrad, gewählt. Zur Sprühtrocknung wird die Dispersion des Polymerisats mit einem Festgehalt von vorzugsweise 20 % bis 70 % gemeinsam mit Schutzkolloiden als Verdüsungshilfe versprüht und getrocknet werden. Als Schutzkolloide können dabei beispielsweise teilverseifte Polyvinylalkohole, Polyvinylpyrrolidone, Stärken, Melaminformaldehydsulfonate, Naphthalinformaldehydsulfonate eingesetzt werden. Bevorzugt werden bei diesem Verfahrensschritt 5 bis 20 Gew% Schutzkolloid, bezogen auf das Polymerisat, zugesetzt.The polymer dispersions are preferably dried by means of spray drying or by means of coagulation of the dispersion and subsequent fluidized bed drying of the coagulum. For Drying is preferred in conventional spray drying systems, where the atomization by means of one-, two- or multi-component nozzles or with a rotating disc can. The outlet temperature is generally in Range from 55 ° C to 100 ° C, preferably 65 ° C to 90 ° C, depending on Plant, Tg of the resin and desired degree of dryness selected. The dispersion of the polymer is used for spray drying a fixed content of preferably 20% to 70% together with Protective colloids sprayed and dried as an atomization aid become. For example, partially saponified can be used as protective colloids Polyvinyl alcohols, polyvinyl pyrrolidones, starches, Melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates be used. Are preferred in this process step 5 to 20% by weight of protective colloid, based on the polymer, added.

    Ein besonderer Vorteil der durch Suspensionspolymerisation hergestellten oder mittels Sprühtrocknung getrockneten Pulver liegt darin, daß dabei aufgrund des Anteils an Schutzkolloid wasseraktivierbare Bindepulver erhalten werden; das heißt die Schmelzviskosität der Polymerpulver läßt sich durch Zugabe von Wasser herabsetzen. Nicht wasseraktivierbare Polymerpulver erhält man beispielsweise durch Isolierung mittels Koagulation und anschließender Wirbelschichttrocknung. Bevorzugt werden zur Faserbindung wasseraktivierbare Pulver eingesetzt. Nicht mit Wasser aktivierbare Pulver sind besser siegelbare Bindemittel und werden dann angewandt, wenn der Faserverbund anschließend noch durch Heißsiegelung mit einem anderen Substrat verbunden werden soll.A particular advantage of suspension polymerization powder produced or dried by spray drying is because of the proportion of protective colloid water-activatable binding powder can be obtained; that is the The melt viscosity of the polymer powder can be increased by adding Reduce water. Polymer powder that cannot be activated by water one, for example, by isolation using coagulation and subsequent fluid bed drying. To be favoured water-activatable powders are used for fiber binding. Not Powders that can be activated with water are better sealable binders and are used when the fiber composite is subsequently by heat sealing with another substrate to be connected.

    Die Polymerpulver haben einen Schmelzindex MFI (Melt Flow Index) von 2 bis 300, vorzugsweise 15 bis 80 g/10 min bei 190 °C und einem Belastungsgewicht von 2.16 kg. Zur Bestimmung des MFI-Wertes wird nach Methode DIN 53735 auf einem Göttfert-MFI-Gerät Modell MPS-D verfahren. Das Molekulargewicht beträgt 15000 bis 800000, vorzugsweise 100000 bis 200000. Das Molekulargewicht ist als Gewichtsmittel, bestimmt mittels Gelpermeationsverfahren (GPC) gegen Natrium-Polystyrolsulfonat-Standards, angegeben. Die bevorzugte Korngröße beträgt 50 bis 400 µm, besonders bevorzugt 100 bis 400 µm.The polymer powders have a melt flow index MFI (Melt Flow Index) from 2 to 300, preferably 15 to 80 g / 10 min at 190 ° C and a load weight of 2.16 kg. To determine the MFI value is determined according to method DIN 53735 on a Göttfert MFI device Move the MPS-D model. The molecular weight is 15,000 to 800,000, preferably 100,000 to 200,000. The molecular weight is the weight average, determined by means of the gel permeation method (GPC) against sodium polystyrene sulfonate standards, specified. The preferred grain size is 50 to 400 µm, particularly preferably 100 to 400 µm.

    Das erfindungsgemäße Verfahren kann auf herkömmlichen Airlaid-Anlagen mit mehreren hintereinandergeschalteten Forming Heads zum Einblasen der Faser- und/oder Pulver-Mischung mit Luft praktiziert werden. Die Anzahl der Forming Heads richtet sich dabei nach dem angestrebten Flächengewicht des Faservlieses und Verfahrensvarianten.The method according to the invention can be used on conventional airlaid systems with several forming heads connected in series for blowing the fiber and / or powder mixture with air be practiced. The number of forming heads is determined according to the desired basis weight of the nonwoven and process variants.

    Im ersten Verfahrensschritt kann das Fasermaterial in Form eines vorgefertigten Faservlieses ausgelegt werden oder es kann mittels Luftlegen eine erste Faserlage aus losen Fasern aufgelegt werden. Wird ein vorgefertigtes Faservlies ausgelegt, wird der Vliesstoff (nonwoven) beispielsweise in Form von Gewirren, Gelegen, als Spinnvlies oder polymergebundenes Vlies ausgelegt. Beim Einsatz von losen Fasern werden in diesem und den nachfolgenden Schritten vorzugsweise kurze Fasern mit einer Faserlänge von ≤ 20 mm, vorzugsweise 1 bis 18 mm, insbesonders 2 bis 12 mm, eingesetzt. Das Flächengewicht des im ersten Schritt ausgelegten Faservlieses bzw. der ausgelegten losen Fasern beträgt 10 bis 50 g/m2.In the first process step, the fiber material can be laid out in the form of a prefabricated fiber fleece, or a first fiber layer made of loose fibers can be laid on by means of air laying. If a prefabricated nonwoven is laid out, the nonwoven is laid out, for example, in the form of knitted fabrics, scrims, spunbonded or polymer-bonded nonwoven. When loose fibers are used, short fibers with a fiber length of 20 20 mm, preferably 1 to 18 mm, in particular 2 to 12 mm, are preferably used in this and the subsequent steps. The weight per unit area of the nonwoven fabric or loose fibers laid out in the first step is 10 to 50 g / m 2 .

    Im nächsten Schritt werden die Fasern und das thermoplastische Polymerpulver getrennt oder als Faser/Pulver-Mischung im Luftstrom in einer Menge von 10 bis 300 g/m2, vorzugsweise von 10 bis 100 g/m2 abgelegt. Im allgemeinen werden im Airlaidverfahren die Fasern und das Faserbindepulver in einem turbulenten Luftstrom, kontinuierlich oder diskontinuierlich, trocken gemischt und anschließend das Gemisch im Luftstrom abgelegt. Dieser Schritt kann ein- oder mehrfach wiederholt werden bis das angestrebte Flächengewicht des Vlieses erreicht ist. In the next step, the fibers and the thermoplastic polymer powder are separated or deposited as a fiber / powder mixture in an air stream in an amount of 10 to 300 g / m 2 , preferably 10 to 100 g / m 2 . In general, in the airlaid process, the fibers and the fiber binding powder are dry-mixed in a turbulent airflow, continuously or discontinuously, and the mixture is then deposited in the airflow. This step can be repeated one or more times until the desired basis weight of the fleece is reached.

    Zweckmäßig wird so vorgegangen, daß die mehrfache Auftragung mittels mehrerer hintereinander angeordneter Forming Heads erfolgt. Die Auftragungsmenge beträgt vorzugsweise 10 bis 100 g/m2 pro Verfahrensschritt. Der Gewichtsanteil an Faserbindepulver beträgt jeweils 1 bis 30 Gew.-%, vorzugsweise 5 bis 15 Gew%, jeweils bezogen auf das Gesamtgewicht an Faser und Polymerpulver.Appropriately, the procedure is such that the multiple application is carried out by means of a plurality of forming heads arranged one behind the other. The application amount is preferably 10 to 100 g / m 2 per process step. The proportion by weight of fiber binding powder is in each case 1 to 30% by weight, preferably 5 to 15% by weight, in each case based on the total weight of fiber and polymer powder.

    Vorzugsweise sollten die Faservliese oder Fasern beim Auslegen eine Restfeuchte von 5 bis 15 Gew.-% aufweisen, da die Restfeuchte ein Anquellen des Polymerpulvers und eine bessere Haftung des Polymerpulvers auf der Faser bewirkt. In einer weiteren bevorzugten Ausführungsform, insbesondere bei der Anwendung von wasseraktivierbaren Polymerpulvern, werden die ausgelegten Faservliese oder Faserlagen, entweder vor dem Auflegen der nächsten Lage oder nach Ablage aller Lagen, mit Wasser oder Dampf befeuchtet um das Polymerpulver zu aktivieren. Dazu werden die einzelnen Lagen mit 5 bis 60 Gew.-%, vorzugsweise 10 bis 35 Gew.-% Wasser, jeweils bezogen auf das Gesamtgewicht von Faser und Polymerpulver, befeuchtet. Die Befeuchtung kann mittels Wasserdampf erfolgen oder auch mittels Besprühen mit Wasser, gegebenenfalls können auch Kombinationen der einzelnen Verfahren eingesetzt werden. Bei der Herstellung von dicken Vliesstoffen wird das Dämpfen mit heißem Wasserdampf bevorzugt.Preferably, the nonwovens or fibers should be laid out have a residual moisture content of 5 to 15% by weight since the residual moisture content swelling of the polymer powder and better adhesion of the polymer powder on the fiber. In another preferred embodiment, especially in the application of water-activatable polymer powders, the designed ones Non-woven fabrics or layers of fibers, either before laying on the next layer or after storing all layers, with water or steam humidified to activate the polymer powder. To the individual layers with 5 to 60 wt .-%, preferably 10 to 35 wt .-% water, each based on the total weight of fiber and polymer powder, moistened. The humidification can using steam or spraying Water, optionally combinations of the individual Procedures are used. When producing thick Steaming with hot steam is preferred for nonwovens.

    Die Trocknung und Verfestigung des ausgelegten Fasermaterials erfolgt im allgemeinen bei Temperaturen von 80°C bis 260°C, vorzugsweise 120°C bis 200°C, gegebenenfalls unter einem Druck von bis zu 100 bar, wobei die Trocknungstemperatur und der anzuwendende Druck primär von der Art des Fasermaterials abhängen. Mit dem erfindungsgemäßen Verfahren werden Faserkörper mit sehr hohem Flächengewicht mittels Luftlegen zugänglich. Das Flächengewicht der Faserkörper beträgt im allgemeinen von 30 g/m2 bis 1000 g/m2, bevorzugt von 60 g/m2 bis 1000 g/m2, insbesondere von 60 g/m2 bis 300 g/m2. The drying and solidification of the laid fiber material is generally carried out at temperatures from 80 ° C to 260 ° C, preferably 120 ° C to 200 ° C, optionally under a pressure of up to 100 bar, the drying temperature and the pressure to be used primarily from Depending on the type of fiber material. With the method according to the invention, fiber bodies with a very high basis weight are accessible by means of air laying. The weight per unit area of the fiber bodies is generally from 30 g / m 2 to 1000 g / m 2 , preferably from 60 g / m 2 to 1000 g / m 2 , in particular from 60 g / m 2 to 300 g / m 2 .

    In einer bevorzugten Ausführungsform können mit dem Faserbindepulver auch pulverförmige Zusatzstoffe miteingebracht werden, beispielweise Superadsorber (SAP), Füllstoffe wie Silicagel, Flammschutzmittel, blähfähige Microperlen oder Aktivkohle. Damit können die Faserkörper für bestimmte Anwendungsgebiete konditioniert werden, ohne daß dazu ein weiterer, aufwendiger Verfahrensschritt erforderlich wird.In a preferred embodiment, the fiber binding powder Powdery additives are also included, for example super adsorber (SAP), fillers such as silica gel, Flame retardants, expandable microbeads or activated carbon. This allows the fiber body for certain areas of application be conditioned without another, more complex Process step is required.

    Bei der Herstellung von Faserkörpern mit sehr hohem Flächengewicht, vorzugsweise von 60 bis 1000 g/m2 kann auch so vorgegangen werden, daß Kombinationen von Polymerpulver und wäßriger Polymerdispersion eingesetzt werden. Dazu können wie beschrieben die Fasern und das Faserbindepulver im Gemisch im Luftstrom zu einem textilen Flächengebilde abgelegt werden und anschließend anstelle der Wasseraktivierung oder zusätzlich zur Wasseraktivierung das Fasergebilde mit einer wäßrigen Polymerdispersion besprüht werden. Dabei kann so vorgegangen werden, daß Polymerpulver und Polymerdispersion dieselbe Polymerbasis haben; man kann aber auch voneinander verschiedene Polymerisate aus der Gruppe der obengenannten Vinylester- bzw. Methacrylsäureester-Polymerisate einsetzen, beispielsweise ein wasseraktivierbares Pulver mit den Fasern ablegen und dieses Fasergebilde mit einer wäßrigen Dispersion eines nicht wasseraktivierbaren, aber siegelbaren Polymerisats besprühen.In the production of fiber bodies with a very high basis weight, preferably from 60 to 1000 g / m 2, it is also possible to use combinations of polymer powder and aqueous polymer dispersion. For this purpose, as described, the fibers and the fiber binding powder can be deposited in a mixture in an air stream to form a textile fabric and then the fiber structure can be sprayed with an aqueous polymer dispersion instead of water activation or in addition to water activation. The procedure here can be such that polymer powder and polymer dispersion have the same polymer base; However, it is also possible to use different polymers from the group of the above-mentioned vinyl ester or methacrylic acid ester polymers, for example depositing a water-activatable powder with the fibers and spraying this fiber structure with an aqueous dispersion of a non-water-activatable but sealable polymer.

    Es kann auch so vorgegangen werden, daß als letzter Verfahrensschritt vor der Wärmebehandlung nur mehr Dispersion aufgesprüht wird. Das Besprühen mit Polymerdispersion kann dabei einseitig oder von beiden Seiten her erfolgen. Neben der besseren Bindung von dicken Fasergebilden führt dies zu Fasergebilden mit besserer Bindung an der Oberflächen und zum Entstauben der Oberfläche der so behandelten Fasergebilde.It can also be done in such a way that the last process step only dispersion sprayed on before the heat treatment becomes. Spraying with polymer dispersion can one-sided or from both sides. Besides the better Binding of thick fiber structures leads to fiber structures with better binding on the surfaces and for dust removal the surface of the fiber structures treated in this way.

    Bei diesen Verfahrensvarianten wird die Polymerdispersion mit einem Festgehalt von vorzugsweise 7 bis 30 % eingesetzt. Die Einsatzmenge an Polymerdispersion beträgt vorzugsweise 2 bis 25 Gew.-% des Faseranteils. Die Trocknung und Verfestigung erfolgt analog der oben beschriebenen Vorgehensweise. Diese Verfahrensvariante wird dann bevorzugt, wenn sehr dicke Fasergebilde gefertigt werden, oder falls die Vliese in einem nächsten Verfahrensschritt laminiert werden sollen.In these process variants, the polymer dispersion is included a fixed content of preferably 7 to 30%. The The amount of polymer dispersion used is preferably 2 to 25% by weight of the fiber content. The drying and solidification takes place analogous to the procedure described above. This process variant is preferred when very thick fiber structures be made, or if the nonwovens in a next Process step to be laminated.

    Bei der Laminierung werden die Fasergebilde in der oben angegebenen Art und Weise, mit oder ohne Aufsprühen von Polymerdispersion, behandelt und anschließend ein weiteres Substrat aufgelegt. Die Verfestigung der Laminate erfolgt unter den oben angegebenen Temperatur- und Druckbedingungen. Bei der Laminierung können zwei gleiche oder unterschiedliche Fasergebilde miteinander verklebt werden oder ein Fasergebilde mit einem weiteren Substrat verklebt werden. Als Substrate eignen sich Kunststoff-Folien wie Polyesterfolien oder Polyolefinfolien, Gewebe und Nonwovens wie Cellulosevliese, Holzfaserplatten wie Preßspanplatten, geschäumte flächige Materialien wie Polyurethanschäume.When lamination, the fiber structures are given in the above Way, with or without spraying of polymer dispersion, treated and then another substrate hung up. The laminates are consolidated under the temperature and pressure conditions given above. When lamination can be two identical or different fiber structures are glued together or a fiber structure with be glued to another substrate. Suitable as substrates plastic films such as polyester films or polyolefin films, Fabrics and nonwovens such as cellulose fleeces, fiberboard such as chipboard, foamed sheet materials like polyurethane foams.

    Es kann auch so vorgegangen werden, daß im letzten Verfahrenschritt vor der Wärmebehandlung nur mehr ein Lage Faser ohne Zusatz von Polymerpulver oder Polymerdispersion abgelegt wird. Man erhält damit Fasergebilde, welche sich vor allem durch geringere Oberflächenklebrigkeit auszeichnen.It can also be done in such a way that in the last procedural step before the heat treatment only one layer of fiber without Addition of polymer powder or polymer dispersion is deposited. You get fiber structures, which are mainly due to smaller Characterize surface stickiness.

    Die mit dem erfindungsgemäßen Verfahren zugänglichen Produkte eignen sich zur Verwendung im Automobilbau oder im Bausektor, beispielsweise als Dämmstoffe oder zur Verwendung im Hygiene bereich, beispielsweise zur Herstellung von Windeln oder Damenbinden.The products accessible by the process according to the invention are suitable for use in the automotive industry or in the construction sector, for example as insulation or for use in hygiene area, for example for the production of diapers or sanitary napkins.

    Mit der erfindungsgemäßen Verfahrensweise werden in kostengünstiger Weise auch voluminöse Faservliese zugänglich, die ohne weitere Konfektionierung nicht delaminieren. Die Faservliese können in einem integrierten Herstellungsprozeß kostensparend weiterverarbeitet werden, beispielsweise zu Laminaten mit sich selbst oder anderen Vliese unter Erhalt von multifunktionellen Composites. Die Polymerpulver haben auch Bindevermögen für funktionelle, pulverförmige Zusatzstoffe, welche häufig in Faservliesen enthalten sind und können diese aufgrund der gleichmäßigen Verteilung wirkungsvoll binden. Im Vergleich zu herkömmlichen Bindefasern erhält man bei Verwendung der Bindepulver bessere Haftung an Naturfasern, eine verbesserte Staubeinbindung ohne daß das Absorptionsvermögen des Airlaids eingeschränkt wird.With the procedure according to the invention will be cheaper Way also voluminous nonwovens accessible without do not delaminate further packaging. The non-woven fabrics can save costs in an integrated manufacturing process can be processed further, for example to form laminates yourself or other fleeces while maintaining multifunctional Composites. The polymer powders also have binding capacity for functional, powdery additives, which are often found in nonwovens are included and can be due to the tie even distribution effectively. Compared to Conventional binding fibers are obtained when using the binding powder better adhesion to natural fibers, improved dust binding without the absorption capacity of the airlaid being restricted becomes.

    Die nachfolgenden Beispiele dienen zur weiteren Erläuterung der Erfindung:The following examples serve for further explanation the invention:

    Vergleichsbeispiel 1:Comparative Example 1:

    Ein Airlaid aus Cellulosefasern (Faserlänge 2 bis 12 mm) mit einem Flächengewicht von 100 g/m2 wurde mit 10 Gew.-% (s/s), bezogen auf das Gesamtgewicht aus Faser und Polymer, einer wäßrigen Dispersion eines selbstvernetzenden Vinylacetat-Ethylen-NMA-Mischpolymerisats beidseitig besprüht und anschließend im Trockenschrank bei einer Temperatur von 180°C und ohne Druck getrocknet. Die Festigkeit des Faservlieses wurde mit einer Schälnahtprüfung getestet. Dazu wurden 40 mm breite Streifen hergestellt und anschließend 5 Einzelstreifen nach ISO 9073-3 getestet und der Mittelwert ermittelt. Die Schälnahtfestigkeit des Airlaids betrug 0.15 N/cm.An airlaid made of cellulose fibers (fiber length 2 to 12 mm) with a basis weight of 100 g / m 2 was, with 10 wt .-% (s / s), based on the total weight of fiber and polymer, an aqueous dispersion of a self-crosslinking vinyl acetate-ethylene -NMA copolymers sprayed on both sides and then dried in a drying cabinet at a temperature of 180 ° C and without pressure. The strength of the nonwoven was tested with a peel seam test. For this purpose, 40 mm wide strips were produced and then 5 individual strips were tested according to ISO 9073-3 and the average was determined. The peel seam strength of the airlaid was 0.15 N / cm.

    Beispiel 2:Example 2:

    Cellulosefasern (Faserlänge 2 bis 12 mm) wurden in einem Flächengewicht von 50 g/m2 ausgelegt und anschließend als Faser/Pulver-Gemisch eine Lage Cellulosefaser in einem Flächengewicht von 50 g/m2 mit zusätzlich 20 Gew.-%, bezogen auf das Gesamtgewicht aus Faser und Pulver, eines pulverförmigen Vinylacetat-Diisopropylfumarat-Copolymers mit 30 Gew.-% Diisopropylfumarat aufgelegt. Das Vlies wurde im Trockenschrank bei den gleichen Bedingungen wie in Vergleichsbeispiel 1 getrocknet. Die Schälfestigkeit betrug 0.38 N/cm. Obwohl nichtvernetzbares Bindemittel eingesetzt wurde, war die Schälnahtfestigkeit bei Pulverbindung deutlich erhöht gegenüber Vergleichsbeispiel 1.Cellulose fibers (fiber length 2 to 12 mm) were laid out in a basis weight of 50 g / m 2 and then a layer of cellulose fiber in a basis weight of 50 g / m 2 with an additional 20% by weight, based on the fiber / powder mixture Total weight of fiber and powder, a powdery vinyl acetate-diisopropyl fumarate copolymer with 30 wt .-% diisopropyl fumarate. The fleece was dried in the drying cabinet under the same conditions as in Comparative Example 1. The peel strength was 0.38 N / cm. Although non-crosslinkable binder was used, the peel seam strength was significantly increased in comparison with comparative example 1.

    Beispiel 3:Example 3:

    Es wurde analog Beispiel 2 vorgegangen, mit dem Unterschied, daß nach dem Auslegen des Vlieses und vor dem Trocknen 30 Gew.-% Wasser, bezogen auf das Gesamtgewicht von Faser und Pulver, aufgesprüht wurden. Die Schälnahtfestigkeit erhöhte sich erneut und betrug 0.41 N/cm.The procedure was analogous to Example 2, with the difference that that after laying out the fleece and before drying 30th % By weight of water, based on the total weight of fiber and Powder that were sprayed on. The peel seam strength increased again and was 0.41 N / cm.

    Beispiel 4:Example 4:

    Es wurde analog Beispiel 2 vorgegangen, mit dem Unterschied, daß 10 Gew.-%, bezogen auf das Gesamtgewicht von Faser und Pulver, einer 70:30-Mischung (w/w) aus dem pulverförmigen Bindemittel gemäß Beispiel 2 und einem SAP-Pulver (Famor SX FAM) eingesetzt wurde. Trotz des hohen Anteils an SAP-Pulver war die Schälnahtfestigkeit mit 0.30 N/cm deutlich höher als beim Einsatz einer größeren Menge vernetzbarer Bindemitteldispersion (Vergleichsbeispiel 1). Es war auch kein Ausstauben des Superadsorber-Pulvers feststellbar.The procedure was analogous to Example 2, with the difference that that 10 wt .-%, based on the total weight of fiber and Powder, a 70:30 mixture (w / w) of the powdered binder according to example 2 and a SAP powder (Famor SX FAM) was used. Despite the high percentage of SAP powder the peel seam strength of 0.30 N / cm is significantly higher than that of the Use of a larger amount of crosslinkable binder dispersion (Comparative Example 1). It wasn't dusting the Superadsorber powder either noticeable.

    Vergleichsbeispiel 5:Comparative Example 5:

    Es wurde analog Beispiel 2 vorgegangen, mit dem Unterschied, daß 10 Gew.-%, bezogen auf das Gesamtgewicht von Faser und Pulver, eines pulverförmigen, hydrophoben Polyolefincopolymers (PE/PP) eingesetzt wurden. Die Schälnahtfestigkeit war mit 0.08 N/cm gegenüber den erfindungsgemäß eingesetzten Vinylester- bzw. (Meth)acrylsäureester-Polymerisaten deutlich reduziert.The procedure was analogous to Example 2, with the difference that that 10 wt .-%, based on the total weight of fiber and Powder, a powdery, hydrophobic polyolefin copolymer (PE / PP) were used. The peel seam strength was with 0.08 N / cm compared to the vinyl ester or (meth) acrylic ester polymers significantly reduced.

    In Abb. 1 ist eine REM-Aufnahme eines mit PE/PP-Bikomponentenfasern thermisch verfestigten Airlaids (100 g/m2) wiedergegeben. Die schlechte Benetzung des Fluff pulps ist gut zu erkennen.In Fig. 1 is a SEM picture of one with PE / PP bicomponent fibers thermally consolidated airlaids (100 g / m2). The poor wetting of the fluff pulp is good too detect.

    Abb. 2 zeigt demgegenüber ein mit einem pulverförmigen Bindemittel (Beispiel 3) verfestigtes Airlaid (100 g/m2), welches sehr gute Benetzung der Fasern aufweist.

    Figure 00160001
    In contrast, Fig. 2 shows an airlaid (100 g / m 2 ) consolidated with a powdered binder (example 3), which has very good wetting of the fibers.
    Figure 00160001

    Claims (12)

    1. A process for producing fibre webs by the airlaid process of laying down the fibres and the pulverulent binder in an air stream, characterized in that it comprises
      a) a first step of laying a fibre web or fibres up to a basis weight of 10 to 50 g/m2,
      b) a subsequent step of laying down fibres and a thermoplastic polymer powder based on polymers of one or more monomers selected from the group of the vinyl esters and (meth)acrylic esters separately or as a mixture in the air stream in an amount of 10 to 300 g/m2 and, if appropriate, repeating this step until the desired basis weight is obtained, and
      c) consolidating the fibre material at temperatures of 80°C to 260°C and at a pressure of up to 100 bar.
    2. A process as claimed in Claim 1, characterized in that the polymer powder is based on short-chain vinyl esters having 1 to 4 carbon atoms in the carboxylic acid moiety and short-chain methacrylic or acrylic esters having 1 to 4 carbon atoms in the ester moiety.
    3. A process as claimed in Claim 1 or 2,
      characterized in that the polymer on which the powder is based is a copolymer which additionally contains units derived from 0.05 to 10.0% by weight, based on the total weight of the monomers, of polar comonomers selected from the group consisting of ethylenically unsaturated mono-and dicarboxylic acids and their amides, ethylenically unsaturated sulphonic acids and their salts, N-vinylpyrrolidone and/or crosslinkable comonomers.
    4. A process as claimed in any of Claims 1 to 3, characterized in that the polymer powder is based on hydrophilic polymers containing not less than 50% by weight of the abovementioned short-chain vinyl esters or (meth)acrylic esters or at least 5% by weight of the polar comonomers mentioned, each percentage being based on the total weight of the monomers.
    5. A process as claimed in any of Claims 1 to 3, characterized in that the polymer powder is based on vinyl ester or (meth)acrylate comonomers which contain at least 20% by weight of one or more hydrophobic comonomers selected from the group consisting of long-chain vinyl esters having 5 to 11 carbon atoms in the ester moiety, aromatic vinyls, vinyl halides, olefins, dienes and also diesters of dicarboxylic acids such as fumaric acid or maleic acid.
    6. A process as claimed in any of Claims 1 to 4, characterized in that the polymers have a glass transition temperature Tg of -40°C to +150°C.
    7. A process as claimed in any of Claims 1 to 5, characterized in that the laid fibre webs or layers are moistened with 5 to 60% by weight, based on the total weight of fibre and fibre-binding powder, of water or steam before the next layer is laid on top or after all the layers have been laid down.
    8. A process as claimed in any of Claims 1 to 7, characterized in that the polymer powder is added together with pulverulent additives such as superabsorbents, fillers, flame retardants, expandable microbeads or activated carbon.
    9. A process as claimed in any of Claims 1 to 8, characterized in that combinations of polymer powder and aqueous polymer dispersion are used.
    10. A process as claimed in any of Claims 1 to 9, characterized in that the last step prior to the heat treatment is carried out by laying down only one layer of fibre without addition of polymer powder or polymer dispersion.
    11. A fibre web having a basis weight of 30 g/m2 to 500 g/m2, obtainable by a process as claimed in any of Claims 1 to 10.
    12. Use of the fibre web of Claim 11 in automotive construction, the building construction sector and the hygiene sector.
    EP00107105A 1999-04-22 2000-04-06 Method of manufacturing airlaid nonwoven fabrics Expired - Lifetime EP1046737B1 (en)

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    DE19918343A DE19918343C2 (en) 1999-04-22 1999-04-22 Process for the production of non-woven fabrics by the airlaid process

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    DE19918343A1 (en) 2000-10-26
    EP1046737A1 (en) 2000-10-25

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